JP4938896B1 - Paint supply system - Google Patents

Abstract

Provided is a paint supply system capable of preventing a pressure fluctuation of a paint in a paint booth flow path.
A paint supply system B includes a paint forward path 3 from a pump discharge side 11 to a booth flow path inlet side 21, a pressure feed sensor s3 for detecting a paint feed pressure upstream of a paint filter 30, and a back pressure valve 44. A paint tank 42 is interposed, the paint return path 4 from the booth flow path outlet side 22 to the pump suction side 12, high pressure / low pressure switching electromagnetic valves 45, 46 for switching the air pressure to the back pressure valve 44, and pressure supply The electric plunger pump 1 is PID controlled so that the paint feed pressure detected by the sensor s3 becomes the target feed pressure, and the high pressure / low pressure switching electromagnetic valves 45 and 46 are set to high pressure or low pressure based on the target feed pressure. And a supply controller 5. Since the followability during the paint consumption in the booth is good, the pressure fluctuation of the paint in the paint booth flow path 2 can be prevented.
[Selection] Figure 4

Description

  The present invention relates to a paint supply system that performs painting on a body or the like of an automobile.

  When the paint supply pump is always operated at a constant output, the power consumption of the paint supply pump is large and the life of the paint supply pump is shortened.

In Patent Document 1, the normal operation and the save operation are automatically switched according to the operation state of the paint gun equipment section, and in the normal operation, the paint supply pump is shift-controlled so that the discharge flow rate becomes the set normal flow value, In the save operation, a paint supply facility is described in which the paint supply pump is shift-controlled so that the discharge flow rate becomes a set save flow rate value smaller than the set normal flow rate value.
Patent Document 2 describes a paint supply facility that reduces pump power consumption by automatically adjusting the output of a paint supply pump according to changes in the operating conditions of the paint gun equipment.
Patent Document 3 includes a pump for circulating paint, a back pressure regulator, a pressure sensor for detecting paint pressure in the painting line, and a control means for controlling the pump and the back pressure regulator. A paint circulation system is described that deactivates the back pressure regulator in mode and operates the pump at a constant speed, activates the back pressure regulator in pressure mode, and controls the pump speed to maintain paint pressure. Yes.

JP 2009-154042 A JP 2008-86998 A Special table 2009-507639

The said patent document 1 has the following subject.
Since the paint consumption at the painting booth is not constant, the pressure of the paint flowing in the paint flow path fluctuates and pulsates. If the pulsation is left unattended, uneven coating occurs, so a pulsation suppressing device such as a surge tank is required.

The said patent document 2 has the following subject.
Since there is a gap between the operation schedule of the paint gun equipment and the actual paint consumption, the control that increases or decreases the output of the paint supply pump according to the change in the operation conditions of the paint gun equipment flows in the paint flow path. The pressure fluctuation of the paint cannot be reliably suppressed.

The said patent document 3 has the following subject.
In the pressure mode, since the paint pressure is detected by the pressure sensor built in the pump, the pressure sensor detects the behavior of the pump, the pressure fluctuation of the paint flowing through the paint flow path is not eliminated, and pulsation remains.

In the flow mode, since the back pressure regulator is inactive, a large amount of paint flows into the paint tank and overflows. The pressure of the paint in the paint flow path varies depending on the location, and air easily enters the paint flow path.
When shifting from the flow rate mode to the pressure mode, it takes time for the paint pressure in the paint flow path to reach a predetermined paint pressure.
The above-mentioned problem is particularly remarkable when the paint flow path is long or when there is a height difference.

  The object of the present invention is to prevent pressure fluctuations of the paint flowing through the paint flow path during painting (high pressure operation) and to stabilize the behavior of the paint flowing through the paint flow path during non-painting (low pressure operation). The provision of supply systems.

(About claim 1)
The paint supply system includes a paint filter interposed in the forward path, a paint forward path from the discharge side of the electric plunger pump to the inlet side of the paint booth channel, a paint application gun connected to the paint booth channel, and a paint filter A paint pressure sensor that detects the paint feed pressure upstream of the paint filter, an air-operated back pressure valve, and a paint tank that stores the paint are installed in the return path. A return pressure sensor for detecting the return pressure of the paint upstream of the back pressure valve, and a return pressure sensor disposed on the return path of the paint from the outlet side of the flow path to the suction side of the electric plunger pump and the back of the back pressure valve, and the electric plunger An inverter for driving the pump, an electropneumatic regulator driven by applying air pressure to the back pressure valve, and a microcomputer, and a paint supply system for controlling the inverter and the electropneumatic regulator And a vessel.

When paint is sprayed from the paint application gun connected to the paint booth flow path to the sprayed object and the paint is consumed, the paint pressure in each paint path (paint booth flow path, paint forward path, paint return path) decreases. To do. The microcomputer performs PID calculation and sends it to the inverter so that the paint feed pressure detected by the pressure feed sensor that detects the paint feed pressure upstream of the paint filter is the target feed pressure. The paint feed pressure is maintained at the target feed pressure for feedback control of the electric plunger pump by adjusting the control voltage.
The level of the electrical signal sent from the microcomputer to the electropneumatic regulator is adjusted so that the paint return pressure detected by the return pressure sensor that detects the paint return pressure in the paint return path upstream of the back pressure valve becomes the target return pressure. In order to control the back pressure valve, the paint return pressure is maintained at the target return pressure.

In this paint supply system, the paint feed pressure in the paint forward path immediately before the paint filter is maintained at the target feed pressure, and the paint return pressure in the paint return path upstream of the back pressure valve is maintained at the target return pressure. The pressure fluctuation of the paint in the flow path can be prevented.
Since the pressure sensor is arranged in the paint forward path immediately before the paint filter and the paint feed pressure upstream of the paint filter is detected, the pressure of the paint flowing in the paint forward path is not easily displaced. In addition, the paint feed pressure can be accurately detected regardless of the period of use of the paint filter.

  Since the microcomputer performs PID calculation so that the paint feed pressure immediately before the paint filter detected by the pressure feed sensor becomes the target feed pressure, the control voltage sent to the inverter is adjusted, and the electric plunger pump is feedback controlled. Good follow-up to changes in paint pressure in the paint forward path.

(About claim 2)
Since the microcomputer sets the target feed pressure and the target return pressure based on the operation signal output according to the operation status of the painting robot that controls the paint injection from the paint application gun to the target, the paint supply pump Power consumption can be reduced.

Specifically, during the period when the paint robot injects the paint from the paint application gun to the target, the microcomputer sets the target feed pressure and target return pressure high so that the paint is properly jetted to the target. To do.
However, during the period when the painting robot does not inject the paint from the paint application gun to the target, it is only necessary to circulate the paint in the painting path at a paint flow rate that prevents the paint from solidifying and settling, so the microcomputer can feed the target. Set the pressure and target return pressure low.

(Claim 3)
The paint supply system includes a paint filter interposed in the forward path, a paint forward path from the discharge side of the electric plunger pump to the inlet side of the paint booth channel, a paint application gun connected to the paint booth channel, and a paint filter A pressure sensor that detects the paint feed pressure upstream of the paint filter, a back pressure valve, and a paint tank that stores paint are placed in the return path, and is placed on the outlet side of the paint booth flow path. Paint return path from the air to the suction side of the electric plunger pump, an inverter for driving the electric plunger pump, a high-pressure / low-pressure switching solenoid valve that switches the back pressure of the back pressure valve into two stages of high pressure and low pressure, and a micro A paint supply controller that has a computer and controls an inverter and a high-pressure / low-pressure switching solenoid valve.

When paint is sprayed from the paint application gun connected to the paint booth flow path to the sprayed object and the paint is consumed, the paint pressure in each paint path (paint booth flow path, paint forward path, paint return path) decreases. To do. The microcomputer performs PID calculation and sends it to the inverter so that the paint feed pressure detected by the pressure feed sensor that detects the paint feed pressure upstream of the paint filter is the target feed pressure. The paint feed pressure is maintained at the target feed pressure for feedback control of the electric plunger pump by adjusting the control voltage.
Further, since the microcomputer sets the high pressure / low pressure switching solenoid valve to high pressure or low pressure based on the target feed pressure, the paint return pressure approaches the target return pressure.

In this paint supply system, the paint feed pressure in the paint forward path immediately before the paint filter is maintained at the target feed pressure, and the paint return pressure in the paint return path upstream from the back pressure valve approaches the appropriate pressure. Can prevent pressure fluctuations in the paint.
Since the pressure sensor is arranged in the paint forward path immediately before the paint filter and the paint feed pressure upstream of the paint filter is detected, the pressure of the paint flowing in the paint forward path is not easily displaced. In addition, the paint feed pressure can be accurately detected regardless of the period of use of the paint filter.

  Since the microcomputer performs PID calculation so that the paint feed pressure immediately before the paint filter detected by the pressure feed sensor becomes the target feed pressure, the control voltage sent to the inverter is adjusted, and the electric plunger pump is feedback controlled. Good follow-up to changes in paint pressure in the paint forward path.

  Since the microcomputer switches the high-pressure / low-pressure switching solenoid valve into two stages of high pressure and low pressure based on the target feed pressure without using an electropneumatic regulator, it is inexpensive.

(About claim 4)
The microcomputer sets the target feed pressure based on the operation signal that is output according to the operation status of the painting robot that controls the paint injection from the paint application gun to the target. Can be reduced.

Specifically, during the period when the paint robot injects the paint from the paint application gun to the object to be ejected, the microcomputer sets the target feed pressure high so that the paint is appropriately ejected to the object to be ejected. Switch the low pressure switching solenoid valve to the high pressure side to increase the paint return pressure.
However, during the period when the painting robot does not inject the paint from the paint application gun to the target, it is only necessary to circulate the paint in the painting path at a paint flow rate that prevents the paint from solidifying and settling, so the microcomputer can feed the target. Set the pressure low and switch the high / low pressure switching solenoid valve to the low pressure side to lower the paint return pressure.

It is explanatory drawing of the coating material supply system which concerns on Example 1 of this invention. It is explanatory drawing which shows the control flow of the whole coating material supply system. It is explanatory drawing which shows the PID control flow of the electric plunger pump of the coating material supply system. It is explanatory drawing of the coating material supply system which concerns on Example 2 of this invention. It is explanatory drawing which shows the control flow of the whole coating material supply system. It is explanatory drawing which shows the PID control flow of the electric plunger pump of the coating material supply system.

  The paint supply system B shown in FIG. 4 includes a paint forward path 3 from the pump discharge side 11 to the booth flow path inlet side 21, a pressure feed sensor s3 that detects the paint feed pressure upstream of the paint filter 30, a back pressure valve 44, The paint tank 42 is interposed, the paint return path 4 from the booth channel outlet side 22 to the pump suction side 12, the high pressure / low pressure switching electromagnetic valves 45 and 46 for switching the air pressure to the back pressure valve 44, and the pressure supply The electric plunger pump 1 is PID controlled so that the paint feed pressure detected by the sensor 3 becomes the target feed pressure, and the high pressure / low pressure switching electromagnetic valves 45 and 46 are set to high pressure or low pressure based on the target feed pressure. And a supply controller 5. Thereby, since the followability during paint consumption in the booth is good, it is possible to prevent the pressure fluctuation of the paint in the paint booth flow path 2.

A paint supply system A according to a first embodiment of the present invention (corresponding to claims 1 and 2) will be described with reference to FIGS.
The paint supply system A includes a paint forward path 3 from the discharge side 11 of the electric plunger pump 1 to the inlet side 21 of the paint booth flow path 2, paint paint guns 31 and 32 connected to the paint booth flow path 2, and paint The paint filter 30 interposed in the forward path 3, the pressure sensor s1 for detecting the paint feed pressure upstream of the paint filter, the back pressure valve 41 and the paint tank 42 are provided in the return path, and the painting booth flow A paint return path 4 from the outlet side 22 of the path 2 to the suction side 12 of the electric plunger pump 1, a return pressure sensor s2 for detecting a paint return pressure in the paint return path 4 upstream of the back pressure valve 41, and an electric plan PLC 50 (programmable logic controller) having an inverter 13 for driving the jar pump 1, an electropneumatic regulator 40 driven by applying air pressure to the back pressure valve 41, and a microcomputer 51 And a coating material supply control unit 5 which is arranged.

The electric plunger pump 1 is a four-ball dual type in which balls are arranged in the inlet and outlet passages of the cylinder, the rotational force of the motor shaft is converted into reciprocating motion by a crank mechanism, and the rod moves in a piston motion in the cylinder. It is.
The painting booth flow path 2 is a two-pipe system, and a hand-painted paint application gun 31 and a paint application gun 32 operated by a multi-axis multi-joint painting robot are connected to the flow path.

  A welding ball valve 33a is interposed in the paint forward path 3 on the upstream side of the paint filter 30, and a pressure supply sensor for detecting the paint pressure immediately before the paint filter 30 is provided in the paint forward path 3 on the upstream side of the weld ball valve 33a. s1 is connected via a screw-in valve 33b.

A weld ball valve 34 is interposed in the paint forward path 3 on the downstream side of the paint filter 30, and a temperature adjusting water heat exchanger 35 is interposed downstream of the weld ball valve 34.
The paint tank 42 is a container for storing paint, and is interposed in the paint return path 4 upstream from the suction side 12 of the electric plunger pump 1.

The back pressure valve 41 is an air operated type, and is interposed in the paint return path 4 between the inlet side 42 a of the paint tank 42 and the outlet side 22 of the paint booth flow path 2.
The back pressure valve 41 is used to apply a back pressure to the paint passing through the valve body and maintain the paint pressure in the paint booth flow path 2 upstream of the paint return path 4 at a predetermined value. The upstream side of the back pressure valve 41 is connected to the outlet side 22 of the painting booth channel 2 via a welding ball valve 43.

The electrical output (4 mA to 20 mA) output from the pressure sensor s1 corresponding to the paint pressure is sent to the A / D conversion unit 55 of the PLC 50. The microcomputer 51 of the PLC 50 determines that the paint feed pressure is equal to the target feed pressure. PID calculation is performed as follows.
Then, the frequency command (4 mA to 20 mA) sent to the inverter 13 via the D / A conversion unit 56 is increased / decreased to change the duty cycle of the pulse width (period is constant), and the electric plunger pump 1 is PWM-controlled.

The return pressure sensor s2 detects the paint return pressure in the paint return path 4 upstream from the back pressure valve 41, and the electrical output (4 mA to 20 mA) corresponding to the paint return pressure is an A / D conversion unit of the PLC 50. 53.
The electropneumatic regulator 40 is an instrument that steplessly increases or decreases the air pressure sent to the back pressure valve 41 in proportion to the electrical signal (paint pressure command; digital value) output from the CC-LINK unit 54 of the PLC 50.
The microcomputer 51 of the PLC 50 performs PID calculation so that the paint return pressure detected by the return pressure sensor s2 becomes the target return pressure, adjusts the level of the electric signal sent to the electropneumatic regulator 40, and controls the back pressure valve 41. Control (see FIGS. 2 and 3).

  When the operation mode is automatic, the operation target feed pressure and the target return pressure are output to the CC-LINK controller unit 57 in accordance with the operation status of the robot process panel 6 that controls the paint injection from the paint application gun 32 to the injection target. The microcomputer 51 sets based on the operation signal 61. Note that the optimal target feed pressure and target return pressure in a predetermined operating state are determined in advance by performing a test operation, and are set on the touch panel 52 (see FIGS. 1 and 2).

The coating material supply system A of this embodiment operates as follows.
The PLC 50 determines whether to perform the high pressure operation or the low pressure operation based on the operation signal 61 output according to the operation state of the robot process panel 6 that controls the paint injection from the paint application gun to the injection target. The target feed pressure and the target return pressure are set based on
The operation signal 61 output from the robot process board 6 includes line operation information indicating whether or not the coating line is in operation, paint color information, paint completion information indicating whether or not the paint has been completed, and operation. Calendar timer information of the scheduled date and time.

  During the high pressure operation in which the coating robot sprays the paint from the paint application gun 32 to the ejected body, the target feed pressure and the target return pressure are set high so that the paint is appropriately ejected to the ejected body. In addition, the target feed pressure and the target return pressure are set low during low pressure operation in which the coating robot does not spray paint from the paint application gun 32 onto the target.

  During high pressure operation in which paint is sprayed from the paint application gun 32 (or paint application gun 31) connected to the paint booth flow path 2 to the object to be ejected and the paint is consumed, each paint path (paint booth flow path 2 The paint pressure in the paint forward path 3 and the paint return path 4) decreases.

  For this reason, the microcomputer 51 of the PLC 50 performs PID calculation so that the paint feed pressure detected by the pressure feed sensor s1 becomes the target feed pressure set higher, and the frequency sent from the D / A conversion unit 56 to the inverter 13 The current value of the command (4 mA to 20 mA) is increased / decreased to change the duty cycle of the pulse width (the period is constant), and the electric plunger pump 1 is PWM controlled (see FIGS. 2 and 3).

Further, the microcomputer 51 of the PLC 50 sends an electric signal (paint pressure) sent from the CC-LINK unit 54 to the electropneumatic regulator 40 so that the paint return pressure detected by the return pressure sensor s2 becomes a high target return pressure. The back pressure valve 41 is controlled by increasing or decreasing the level of the command (see FIGS. 2 and 3).
As a result, the paint feed pressure is maintained at a high target feed pressure suitable for the paint spray from the paint application gun 32 to the ejected body.

  During low pressure operation in which paint is not sprayed from the paint application gun 32 connected to the paint booth flow path 2 and the paint is not consumed, each paint path (paint booth flow path 2, paint forward path 3, paint return path) 4) The paint pressure inside increases.

  For this reason, the microcomputer 51 of the PLC 50 performs PID calculation so that the paint feed pressure detected by the pressure feed sensor s1 becomes the target feed pressure set low, and the frequency sent from the D / A conversion unit 56 to the inverter 13 The current value of the command (4 mA to 20 mA) is increased / decreased to change the duty cycle of the pulse width (the period is constant), and the electric plunger pump 1 is PWM controlled (see FIGS. 2 and 3).

Further, the microcomputer 51 of the PLC 50 sends an electric signal (paint pressure) sent from the CC-LINK unit 54 to the electropneumatic regulator 40 so that the paint return pressure detected by the return pressure sensor s2 becomes a target return pressure set low. The back pressure valve 41 is controlled by increasing or decreasing the level of the command (see FIGS. 2 and 3).
As a result, the paint feed pressure is maintained at a low target feed pressure.

The coating material supply system A of the present embodiment has the following advantages.
During high pressure operation, the paint supply system A maintains the paint feed pressure in the paint forward path 3 upstream of the paint filter 30 at a high target feed pressure suitable for high pressure operation, and the paint supply system A in the paint return path 4 upstream of the back pressure valve 41. Since the paint return pressure is maintained at a high target return pressure suitable for high-pressure operation, it is possible to prevent the pressure fluctuation of the paint in each paint path (paint booth flow path 2, paint forward path 3, paint return path 4).

  During low pressure operation, the paint feed pressure in the paint forward path 3 upstream of the paint filter 30 is maintained at a low target feed pressure suitable for low pressure operation, and the paint return pressure in the paint return path 4 upstream of the back pressure valve 41. Is maintained at a low target return pressure suitable for low pressure operation, it is possible to prevent pressure fluctuations in the paint in each paint path (paint booth flow path 2, paint forward path 3, paint return path 4).

  Since the paint supply system A of the present embodiment can prevent the pressure fluctuation of the paint in each paint path, a pulsation suppressing device such as a surge tank is unnecessary.

  The paint supply system A of this embodiment does not require manual operation such as manually operating the manual back pressure valve or adjusting the paint pump capacity based on the visual value of the pressure sensor. Because it can be done, it takes less time and excels in safety.

  The microcomputer 51 of the PLC 50 performs PID calculation so that the paint feed pressure detected by the pressure feed sensor s1 becomes the target feed pressure, and the current of the frequency command (4 mA to 20 mA) sent from the D / A conversion unit 56 to the inverter 13. Since the electric plunger pump 1 is feedback-controlled by increasing / decreasing the value, the followability to the change of the paint pressure in the paint forward path 3 is good.

  The PLC 50 determines whether to perform the high pressure operation or the low pressure operation based on the operation signal 61 output according to the operation status of the robot process panel 6 that controls the paint injection from the paint application gun 32 to the target. Since the target feed pressure and the target return pressure are set based on the contents, the power consumption of the electric plunger pump 1 can be reduced by the amount of low pressure operation.

  Specifically, at the time of high pressure operation in which the painting robot injects the paint from the paint application gun 32 to the object to be ejected, the microcomputer 51 of the PLC 50 causes the target feed pressure and Set the target return pressure higher. Further, when the painting robot stops painting without spraying the paint from the paint application gun 32 to the object to be ejected, it is only necessary to circulate the paint through the painting path at a paint flow rate that prevents the paint from solidifying and paint settling. The microcomputer 51 sets the target feed pressure and the target return pressure low.

A paint supply system B according to a second embodiment of the present invention (corresponding to claims 3 and 4) will be described with reference to FIGS.
The paint supply system B includes a paint forward path 3 from the discharge side 11 of the electric plunger pump 1 to the inlet side 21 of the paint booth flow path 2, paint paint guns 31 and 32 connected to the paint booth flow path 2, and paint The paint filter 30 interposed in the forward path 3, the pressure sensor s3 for detecting the paint feed pressure upstream of the paint filter 30, the back pressure valve 44 and the paint tank 42 are provided in the return path, and the paint booth. The paint return path 4 from the outlet side 22 of the flow path 2 to the suction side 12 of the electric plunger pump 1, the inverter 13 for driving the electric plunger pump 1, and the high pressure for switching the back pressure of the back pressure valve 44 The low pressure switching electromagnetic valves 45 and 46 and the paint supply controller 5 provided with the PLC 50 having the microcomputer 51 are provided.

The electric plunger pump 1 is the same as that of the first embodiment. Balls are arranged on the inlet and outlet passages of the cylinder, the rotational force of the motor shaft is converted into reciprocating motion by a crank mechanism, and the rod is moved inside the cylinder. It is a four-ball double system that moves the piston.
The painting booth channel 2 is a two-pipe system similar to that of the first embodiment, and a paint coating gun 31 for wiping and a coating gun 32 controlled by an articulated painting robot are connected to the channel.

  A welding ball valve 33a is interposed in the paint forward path 3 on the upstream side of the paint filter 30, and a pressure supply sensor for detecting the paint pressure immediately before the paint filter 30 is provided in the paint forward path 3 on the upstream side of the weld ball valve 33a. s3 is connected via a screw-in valve 33b.

A weld ball valve 34 is interposed in the paint forward path 3 on the downstream side of the paint filter 30, and a temperature adjusting water heat exchanger 35 is interposed downstream of the weld ball valve 34.
The paint tank 42 is a container for storing paint, and is interposed in the paint return path 4 upstream from the suction side 12 of the electric plunger pump 1.

The back pressure valve 44 is interposed in the paint return path 4 between the inlet side 42a of the paint tank 42 and the outlet side 22 of the paint booth flow path 2, and applies back pressure to the paint passing through the valve body.
The high pressure / low pressure switching electromagnetic valves 45 and 46 are for setting the back pressure of the back pressure valve 44 to a high pressure or a low pressure.

The electrical output (4 mA to 20 mA) output from the pressure sensor s3 corresponding to the paint pressure is sent to the A / D conversion unit 55 of the PLC 50. The microcomputer 51 of the PLC 50 determines that the paint feed pressure is equal to the target feed pressure. PID calculation is performed as follows.
Then, the frequency command (4 mA to 20 mA) sent to the inverter 13 via the D / A conversion unit 56 is increased / decreased to change the duty cycle of the pulse width (period is constant), and the electric plunger pump 1 is PWM-controlled.
Furthermore, the microcomputer 51 of the PLC 50 sets the high pressure / low pressure switching electromagnetic valves 45 and 46 to high pressure or low pressure based on the magnitude of the target feed pressure.

  When the operation mode is automatic, the operation target feed pressure is output to the MELSEC NET / H unit 58 according to the operation status of the robot process panel 6 that controls the paint injection from the paint application gun 32 to the injection target. Is set by the microcomputer 51 based on the above. Note that the optimum target feed pressure in a predetermined operation state is determined in advance by performing a test operation, and is set on the touch panel 52 (see FIGS. 4 and 5).

The paint supply system B of this embodiment operates as follows.
The microcomputer 51 sets a target feed pressure based on an operation signal 61 output from the robot process board 6 in accordance with the operation status of the painting robot that controls the coating material spraying from the coating material application gun 32 to the spray target.

  During the high pressure operation in which the coating robot sprays the paint from the paint application gun 32 to the ejected body, the target feed pressure is set high so that the paint is appropriately ejected to the ejected body. In addition, the target feed pressure is set low during low-pressure operation in which the coating robot does not spray paint from the paint application gun 32 onto the target.

  During the painting operation in which paint is sprayed from the paint application gun 32 (or paint application gun 31) connected to the paint booth flow path 2 to the ejected object and the paint is consumed, each paint path (paint booth flow path 2 The paint pressure in the paint forward path 3 and the paint return path 4) decreases.

For this reason, the microcomputer 51 of the PLC 50 performs PID calculation so that the paint feed pressure detected by the pressure feed sensor s3 becomes the target feed pressure set higher, and the frequency sent from the D / A conversion unit 56 to the inverter 13 The current value of the command (4 mA to 20 mA) is increased or decreased to change the duty cycle of the pulse width (the period is constant), and the electric plunger pump 1 is PWM-controlled.
Further, the microcomputer 51 of the PLC 50 sets the high pressure / low pressure switching electromagnetic valves 45 and 46 to the high pressure side via the output unit 59 in response to the high target feed pressure, and the back pressure of the back pressure valve 44 is increased. Switch to the side.
As a result, the paint feed pressure is maintained at a high target feed pressure suitable for the paint spray from the paint application gun 32 to the ejected body.

  Also, during low pressure operation in which paint is not sprayed from the paint application gun 32 connected to the paint booth flow path 2 and the paint is not consumed, each paint path (paint booth flow path 2, paint forward path 3, paint paint flow) The paint pressure in the return path 4) increases.

  Therefore, the microcomputer 51 of the PLC 50 performs the PID calculation so that the paint feed pressure detected by the pressure feed sensor s3 becomes the target feed pressure set low, and the frequency sent from the D / A conversion unit 56 to the inverter 13 The current value of the command (4 mA to 20 mA) is increased / decreased to change the duty cycle of the pulse width (period is constant), and the electric plunger pump 1 is PWM-controlled (FIGS. 5 and 6).

Further, the microcomputer 51 of the PLC 50 sets the high pressure / low pressure switching electromagnetic valves 45 and 46 to the low pressure side corresponding to the target feed pressure set low, and switches the back pressure of the back pressure valve 44 to the low pressure side.
As a result, the paint circulates in the paint path at a paint flow rate that prevents the paint from solidifying and paint settling.

  If the coating material supply system of the present invention is used, fluctuations in the coating pressure in the coating path can be prevented.

A, B Paint supply system s1 Pressure sensor s2 Return pressure sensor s3 Pressure sensor 1 Electric plunger pump 2 Paint booth path 3 Paint forward path 4 Paint return path 5 Paint supply controller 11 Discharge side 12 Suction side 13 Inverter 21 Inlet Side 31 Paint filter 40 Electropneumatic regulator 41 Back pressure valve 42 Paint tank 42a Inlet side 51 Microcomputer

Claims (4)

A paint filter is provided in the forward path, the paint forward path from the discharge side of the electric plunger pump to the inlet side of the paint booth flow path,
A paint gun connected to the paint booth flow path;
A pressure sensor that is disposed in the paint forward path immediately before the paint filter and detects the paint feed pressure upstream of the paint filter;
An air operated back pressure valve and a paint tank for storing paint are interposed in the return path, and a paint return path from the outlet side of the paint booth channel to the suction side of the electric plunger pump,
A return pressure sensor that is disposed in the paint return path immediately before the back pressure valve and detects the paint return pressure upstream of the back pressure valve; and an inverter for driving the electric plunger pump;
An electropneumatic regulator that drives the back pressure valve by applying air pressure;
A paint supply system having a microcomputer and comprising a paint supply controller for controlling the inverter and the electropneumatic regulator,
The microcomputer performs feedback control of the electric plunger pump by performing a PID calculation so that the paint feed pressure detected by the pressure feed sensor becomes a target feed pressure and adjusting the control voltage sent to the inverter.
The paint supply system, wherein the back pressure valve is controlled by adjusting a level of an electric signal sent to the electropneumatic regulator so that a paint return pressure detected by the return pressure sensor becomes a target return pressure.   The microcomputer sets the target feed pressure and the target return pressure based on an operation signal output in accordance with an operation state of a painting robot that controls the coating material spraying from the coating material application gun to the target object. The paint supply system according to claim 1, wherein A paint filter is provided in the forward path, the paint forward path from the discharge side of the electric plunger pump to the inlet side of the paint booth flow path,
A paint gun connected to the paint booth flow path;
A pressure sensor that is disposed in the paint forward path immediately before the paint filter and detects the paint feed pressure upstream of the paint filter;
A back pressure valve and a paint tank for storing paint are interposed in the return path, and a paint return path from the outlet side of the coating booth channel to the suction side of the electric plunger pump;
An inverter for driving the electric plunger pump;
A high-pressure / low-pressure switching solenoid valve for switching the back pressure of the back pressure valve between two stages of high pressure and low pressure;
A paint supply system having a microcomputer and comprising a paint supply controller for controlling the inverter and the high-pressure / low-pressure switching solenoid valve,
The microcomputer performs feedback control of the electric plunger pump by performing a PID calculation so that the paint feed pressure detected by the pressure feed sensor becomes a target feed pressure and adjusting the control voltage sent to the inverter. The paint supply system, wherein the high-pressure / low-pressure switching solenoid valve is set to a high pressure or a low pressure based on a magnitude of the target feed pressure.   The microcomputer sets the target feed pressure based on an operation signal output in accordance with an operation state of a painting robot that administers coating material spraying from the coating material application gun to an object to be ejected. 3. The paint supply system according to 3.

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