JPH0673652B2 - Coating agent supply device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating agent supply device that supplies a coating agent to a coating machine such as an electrostatic coating machine or an air spray gun at a predetermined flow rate.

[Prior art and its problems]

A paint machine such as an air spray gun is connected to a paint circulation system to supply paint at a predetermined pressure.
Since the feed pressure from the paint circulation system changes depending on the liquid level of the paint in the paint tank and the usage conditions of other coating machines connected to the paint circulation system, the feed pressure from the paint circulation system is usually adjusted. The pressure is set to a high value, and the feed pressure of the paint is reduced to a predetermined set pressure via a pressure regulator such as a paint regulator, and the paint is supplied to the coating machine in a state where it is maintained constant.

However, when strict flow rate control is required, for example, in the case of supplying the main component and the curing agent of the two-liquid mixed type paint, the above-mentioned paint regulator cannot strictly maintain the flow rate constant.

Therefore, in order to keep the amount of paint supplied constant, a rotary pump such as a gear pump is installed as a constant pump between the paint circulation system and the coating machine, and the rotary pump is rotated at a preset number of revolutions. It was decided to supply the paint at a constant flow rate to the painting machine by driving it.

However, in this case, when a pressure difference occurs between the suction port side and the discharge port side of the rotary pump, internal leakage occurs in the rotary pump, and when the pressure on the discharge port side increases, the paint flows back. On the contrary, if the pressure on the discharge side decreases and the pressure on the suction side relatively increases, the paint will be fed more than necessary, so if the pressure difference between the suction side and the discharge side fluctuates, the paint There is a problem that the flow rate cannot be maintained constant.

[Object of the Invention]

Therefore, the present invention uses a rotary pump such as a gear pump as a metering pump, and adjusts the pressure difference between the suction port side and the discharge port side of the pump when the pressure difference fluctuates to adjust the supply flow rate of the coating agent. An object is to provide a coating agent supply device that can be maintained constant.

[Structure of Invention]

To achieve this object, the present invention provides a coating agent supply adapted to supply a coating agent fed from a coating agent supply source at a predetermined pressure to a coating machine at a predetermined set pressure via a pressure regulator. In the device, a rotary pump driven at a preset number of revolutions is interposed between the pressure regulator and the applicator, and detects the coating agent supply pressure on the discharge port side of the rotary pump. A pressure control device for adjusting the set pressure of the pressure adjuster is arranged so that the pressure difference between the suction port side and the discharge port side of the rotary pump becomes a predetermined value.

[Operation of the invention]

According to the present invention, since the coating agent supplied from the coating agent supply source is supplied to the coating machine via the rotary pump driven at a preset predetermined number of rotations, the coating agent is supplied from the coating agent supply source. Even if there is some fluctuation in the supply pressure, the rotary pump discharges the coating agent at a substantially constant flow rate, and the flow rate of the coating agent supplied to the coating machine is maintained substantially constant.

In addition, the pressure sensor detects the supply pressure of the coating agent on the outlet side of the rotary pump, and the pressure controller adjusts the set pressure of the pressure regulator according to the output of the pressure sensor. Since the pressure difference between the suction port and the suction port is adjusted to a predetermined value, it is necessary to prevent fluctuations in the flow rate due to internal leakage of the rotary pump caused by fluctuations in the pressure difference and maintain the supply flow rate constant. You can

Also, if the pressure on both the discharge side and the suction side of the rotary pump is detected and the set pressure of the pressure regulator is adjusted so that the pressure difference becomes a predetermined value, there was an error in the pressure regulator itself. However, since the pressure difference between the discharge port side and the suction port side can be maintained constant, it is possible to more reliably prevent the flow rate fluctuation caused by internal leakage of the rotary pump.

[Example I]

Hereinafter, the present invention will be specifically described based on the embodiments shown in the drawings.

The figure is a flow sheet showing an example of the coating agent supply apparatus according to the present invention.

In the drawing, reference numeral 1 denotes a paint circulating system (coating agent supply source) for circulating and supplying the paint in a paint tank 2 at a predetermined pressure, for example, by a pump 3, and a spray gun (painting machine) 4 is provided in the paint circulating system 1. A gear pump (rotary pump) 7 as a metering pump driven by a motor 6 is interposed between the coating machine 4 and the paint regulator 5 and is connected via a regulator 5.

Reference numeral 8 is a drive control device for controlling the rotation speed of the motor 6 for driving the gear pump 7. By setting the paint supply flow rate in the control device 8, the motor is driven at a predetermined rotation speed according to the supply flow rate. 6 is driven so that the paint supplied from the paint circulation system 1 at a predetermined pressure can be discharged by the gear pump 7 at a desired flow rate.

The reference numeral 9 indicates the set pressure of the paint regulator 5 so that when the pressure difference between the suction port 7A side and the discharge port 7B side of the gear pump 7 changes, the pressure difference becomes a predetermined value (for example, 0). A pressure adjusting device for adjusting, wherein a pressure sensor 10 for detecting the feed pressure of the paint at the discharge port 7B of the gear pump 7 is connected to the input side, and the paint circulating system 1 to the gear pump 7 is connected to the output side thereof. A paint regulator 5 for adjusting the feed pressure of the paint to be fed is connected, and a control signal C for adjusting the set pressure of the paint regulator 5 is output according to the output signal of the pressure sensor 10. .

Reference numeral 11 denotes a pistol valve which is interlocked with a trigger (not shown) of the spray gun 4, which supplies paint to the spray gun 4 from the gear pump 7 when the trigger is pulled and the trigger is pulled. When not present, the paint discharged from the gear pump 7 is returned to the paint tank 2 of the paint circulating system 1.

The above is an example of the configuration of the present invention, and its operation will be described below.

First, the pump 3 of the paint circulation system 1 is started to pump the paint at a predetermined pressure (for example, 3 kg / cm ² ), and the pressure control device 9 is set to the initial setting pressure of the paint regulator 5 (for example, 1 kg / cm ² ). input.

Then, when a desired paint supply amount is set in the drive control device 8 and the gear pump 7 is driven, the gear pump 7 is driven at a predetermined rotation speed according to the paint supply amount, and the paint circulation system 1 operates at 3 kg / cm ² . The paint fed under pressure is reduced to 1 kg / cm ² by the paint regulator 5, and then discharged from the gear pump 7 at a desired flow rate.

At this time, since the trigger of the spray gun 4 has not been pulled yet, the paint discharged from the gear pump 7 is returned to the paint circulating system 1 via the piston valve 11.

Here, when the trigger of the spray gun 4 is pulled to paint an object to be coated (not shown), the piston valve 11 is switched, and the paint is supplied to the spray gun 4 at a constant flow rate.

When the feed pressure on the discharge port 7B side of the gear pump 7 changes due to the usage state of the spray gun 4, for example, the position (height) of the spray gun 4, the degree of bending of the paint hose, etc., the change is detected by the pressure sensor 10. To be detected.

Here, the delivery pressure on the discharge port 7B side is now 1 kg / cm ² to 1.1 k
Assuming that the pressure has risen to g / cm ² , the pressure sensor 10 detects this and the control signal C is output from the pressure control device 9 to set the pressure of the paint regulator 5 from 1.0 kg / cm ² to 1.1 kg / cm ^2. Be raised to.

Therefore, the paint that has been pressure-fed at 3 kg / cm ² from the paint circulation system 1 is decompressed to 1.1 kg / cm ² by the paint regulator 5 and sent to the gear pump 7, and the suction port 7A side and the discharge port of the pump 7 are supplied. Since the pressures on the 7B side are equal, the paint can be fed at a constant flow rate without causing a reverse flow due to internal leakage in the gear pump 7.

Conversely, the delivery pressure on the discharge port 7B side is 1.1 kg / cm ² to 0.9 kg.
When the pressure decreases to / cm ² , the pressure sensor 10 detects this and the control signal C is output from the pressure control device 9 to decrease the set pressure of the paint regulator 5 from 1.1 kg / cm ² to 0.9 kg / cm ^2. It

Therefore, the paint, which had been decompressed to 1.1 kg / cm ² until now, is further decompressed to 0.9 kg / cm ² and delivered to the gear pump 7, so that the pressure on the suction port 7A side is discharged to the discharge port 7B.
The pressure is reduced to the side pressure, and internal leakage does not cause discharge above the set flow rate.

As described above, even if the pressure on the discharge port 7B side of the gear pump 7 changes, the pressure sensor 10 detects this and adjusts the set pressure of the paint regulator 5 so that the pressure balanced state is maintained. Since this is done, internal flow does not occur in the gear pump 7, and the supply flow rate of the paint is maintained constant.

Example II

FIG. 2 is a flow sheet showing the main part of another embodiment of the present invention.

The same parts as those in FIG. 1 are designated by the same reference numerals and detailed description thereof will be omitted.

In this embodiment, pressure sensors 10A and 10B are provided on both the suction port 7A and the discharge port 7B side of the gear pump 7, and the pressure control device 9 controls the pressure difference detected by the pressure sensors 10A and 10B. A control signal C for adjusting the set pressure of the paint regulator 5 so that the set value (for example, 0.2 kg / cm ² ) is maintained is output.

That is, since the pressure regulated by the paint regulator 5 is confirmed by the pressure sensor 10A and a closed loop for feeding back this is formed, even if the set pressure of the paint regulator 5 has an error, the suction of the gear pump 7 mouth
The pressure difference between the 7A side and the discharge port 7B side can be accurately maintained at a predetermined value.

Thus, according to this embodiment, the discharge port 7B of the gear pump 7 is
Not only the side but also the feed pressure of the paint on the suction port 7A side is measured, so that more reliable pressure control can be performed.

Example III

FIG. 3 is a flow sheet showing a main part of still another embodiment. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, a gear pump driven by an electric motor 12 instead of the paint regulator 5 as a pressure regulator.
Intake port of gear pump 7 as a metering pump using 13
When a pressure difference is generated between the 7A side and the discharge port 7B side, the pressure control device 9 outputs a control signal C for increasing or decreasing the rotation speed of the electric motor 12 to the inverter 14 to discharge the gear pump 13 (set pressure). Pressure) is adjusted.

Then, when pressure fluctuations occur on the suction port 7A side and the discharge port 7B side of the gear pump 7 as a metering pump, the pressure sensor
This is detected by 10A and 10B, and the pressure on the suction port 7A side is the discharge port.
When it becomes relatively higher than the pressure on the 7B side, the control signal C is output from the pressure control device 9 so as to reduce the rotation speed of the motor 12, and the discharge amount of the gear pump 13 as a pressure regulator is reduced. The pressure on the suction port 7A side of the gear pump 7 decreases and becomes equal to the pressure on the discharge port 7B side.

On the contrary, when the pressure on the suction port 7A side becomes relatively lower than the pressure on the discharge port 7B side, the inverter 14 from the pressure control device 9 instructs the inverter 14 to increase the rotation speed of the motor 12. Is output, the discharge amount of the gear pump 13 as a pressure regulator increases, and the suction port of the gear pump 7 as a metering pump.
The pressure on the 7A side rises and becomes equal to the pressure on the discharge port 7B side.

As described above, according to the present embodiment, the rotation speed of the gear pump 13 as a pressure regulator is controlled so that the pressures on the suction port 7A side and the discharge port 7B side of the gear pump 7 as a metering pump become equal. As a result, internal leakage due to a pressure difference between the suction port 7A side and the discharge port 7B side does not occur in the gear pump 7 as a metering pump, and therefore the discharge amount of the gear pump 7 as a metering pump is always constant. Will be maintained.

In the description of the above embodiment, only the case where the gear pump 7 is used as the rotary pump has been described, but the present invention is not limited to this, and any rotary pump such as a vane pump or a screw pump can be applied.

Further, the pressure regulator is not limited to the paint regulator 5 and the gear pump 13, but any other regulating valve or continuous discharge type pump can be arbitrarily applied.

Furthermore, in the examples, only the case where a paint is used as the coating agent has been described.
It can be applied as an arbitrary coating agent supply device such as ink, and when it is used as a main component and curing agent supply device of a two-liquid mixed type paint, the main component supply device and curing agent supply device to which the present invention is applied are used. It suffices to arrange them side by side and mix the supplied main agent and curing agent with a mixer and supply them to the spray gun 4.

〔The invention's effect〕

As described above, according to the present invention, the coating agent supplied from the coating agent supply source is supplied to the coating machine via the rotary pump driven at a predetermined rotation speed set in advance. Even if there is some fluctuation in the agent supply pressure, it is possible to maintain a constant flow rate of the coating agent discharged from the rotary pump and supplied to the coating machine. Even if there is a pressure difference between the discharge side and the suction side, the pressure sensor detects it and adjusts the set pressure of the pressure regulator to bring the pressure difference between the discharge side and the suction side to a specified value. Since it is designed to be maintained, there is an excellent effect that fluctuations in the flow rate due to internal leakage of the rotary pump can be eliminated.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an example of the coating agent supply device according to the present invention, FIG. 2 is a flow sheet showing another embodiment, and FIG. 3 is a flow sheet showing still another embodiment. Explanation of symbols 1 ... Paint circulation system (coating agent supply source), 2 ... Paint tank, 3 ... Pump, 4 ... Spray gun (applicator), 5
…… Paint regulator (pressure regulator), 7 …… Gear pump (rotary pump), 8 …… Drive control device, 9 …… Pressure adjusting device, 10,10A, 10B …… Pressure sensor, 12 …… Electric motor, 13 ...... Gear pump (pressure regulator).

Claims (4)

[Claims] 1. A coating material fed from a coating material feed source (2) at a predetermined pressure is supplied to a coating machine (4) at a predetermined set pressure via a pressure regulator (5, 13). In the coating agent supply device, a rotary pump (7) driven at a predetermined rotational speed set in advance is interposed between the pressure regulator (5, 13) and the coating machine (4), The pressure difference between the suction port side (7A) and the discharge port side (7B) of the rotary pump (7) is detected by detecting the supply pressure of the coating agent on the discharge port side (7B) of the pump (7). A pressure control device (9) for adjusting the set pressure of the pressure regulator (5, 13)
A coating agent supply device, wherein: 2. The pressure control device (9) detects a pressure difference between a discharge port side (7B) and a suction port side (7A) of a rotary pump (7), and the pressure regulator according to the pressure difference. (5,13)
The coating agent supply device according to claim 1, wherein the set pressure is adjusted. 3. The coating agent supply device according to claim 1, wherein the pressure regulator (5) is a regulator. 4. The coating agent supply device according to claim 1, wherein the rotary pump (7) is a gear pump.