JPH0673654B2 - Coating agent supply device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] In the present invention, a plurality of reciprocating pumps that press the coating agent at a constant flow rate are connected in parallel via an applicator, and these reciprocating pumps operate alternately. The present invention relates to a coating agent supply device configured so that a fixed amount of coating agent is pressure-fed and supplied to a coating machine without interruption.

[Prior art and its problems]

For example, in automobile painting where extremely strict painting quality is required, the flow rate of the paint that is pressure-fed to a painting machine such as a spray gun is kept constant to cause painting defects due to changes in the paint spray amount and spray pattern diameter. Must be prevented.

For this reason, conventionally, a flow rate diameter for detecting the flow rate of the paint is provided in the paint supply pipe in which the paint pressure pump is interposed, and the rotation speed of the paint pressure pump is controlled based on the detection value of the flow meter. As a result, the flow rate of the paint that is pressure-fed to the coating machine is kept constant.

However, when using a high-viscosity paint such as metallic paint, the viscosity of the flow meter provided in the coating agent supply pipe does not work correctly or causes a failure, and pressure feeding to the coating machine occurs. There is a drawback in that the flow rate of the applied coating agent cannot be controlled reliably.

Therefore, in order to ensure that even a high-viscosity coating agent can always be pressure-fed and supplied to the coating machine at a constant flow rate, the present applicant, as shown in FIG.
(Or piston) A pair of double-acting reciprocating pumps 4A and 4B in which a coating fluid chamber 2 and a working fluid chamber 3 are formed adjacent to each other are alternately operated to feed the coating fluid to the coating machine 5 under pressure without interruption. An agent supply device has been proposed (see Japanese Utility Model Laid-Open No. 62-170166).

This coating agent supply device is configured such that the coating agent sucked into the coating agent chamber 2 of each reciprocating pump 4A and 4B is squeezed out by the working fluid supplied into the working fluid chamber 3. By controlling the flow rate of the working fluid sent to the working fluid chamber 3 to be constant, the coating agent in the coating agent chamber 2 can be constantly pressure-fed and supplied to the coating machine.

That is, since the flow rate of the coating agent pressure-fed and supplied to the coating machine 5 can be detected by replacing it with the flow rate of the working fluid, a flow meter is provided in the coating agent supply pipeline through which the coating agent is pressure-fed as in the conventional case. It is not necessary to install a flow meter in the working fluid supply line to maintain a constant flow rate of the working fluid, and even when a high clay coating agent is used, the flow meter may be out of order or malfunction. Never.

However, according to the experiments conducted by the present inventors, a plurality of reciprocating pumps 4A and 4B that press the coating agent by the working fluid supplied at a constant flow rate as described above are alternately operated to cause the coating machine 5 to apply the coating agent. Each reciprocating pump 4 when pumping
It was found that when switching between A and 4B, a pulsating flow is generated in the coating material being fed under pressure to the coating machine 5.

When this pulsating flow occurs, the amount of coating agent sprayed by the coating machine 5,
The spray pattern changes temporarily, resulting in uneven coating.

[Object of the Invention]

Therefore, the present inventors further conducted experiments, and one of the causes for causing the pulsating flow in the coating agent pressure-fed to the coating machine as described above was due to the coating agent being extruded from one reciprocating pump and the other reciprocating pump. The present invention has been completed by noting that there is a pressure difference with the stored coating agent, and the pressure of the working fluid extruded from each reciprocating pump by the coating agent supplied from the coating agent supply source is The reciprocating pump adjusts the pressure to the same as the pressure of the coating agent being fed to the coating machine by the reciprocating pump and prevents the pulsating flow of the coating agent that occurs when switching between the reciprocating pumps. The purpose is to do.

[Structure of Invention]

In order to achieve this object, the present invention operates a diaphragm or a piston by a working fluid injected from one port at a constant flow rate so that the coating agent injected from the other port is adjusted according to the flow rate of the working fluid. A plurality of double-acting type reciprocating pumps that are configured to press out at a constant flow rate are connected in parallel to the coating machine, and the reciprocating pumps are alternately operated to apply a fixed amount of the coating agent. In a coating agent supply device configured to be continuously pressure-fed and supplied to a machine, a pressure sensor for detecting a supply pressure of the coating agent is interposed in a pipe line for supplying the coating agent from each of the reciprocating pumps to the coating machine. At the same time, based on the pressure detection signal of the pressure sensor,
A pressure adjusting valve for setting the discharge pressure of the working fluid discharged from each reciprocating pump to the same as the supply pressure of the coating agent supplied to the coating machine is provided in the return pipe for returning the working fluid from each reciprocating pump. It is characterized by that.

[Operation of the invention]

According to the present invention, the pressure sensor detects the supply pressure of the coating agent that is extruded from each reciprocating pump and pressure-fed to the coating machine,
By controlling the pressure adjusting valve based on the pressure detection signal of the pressure sensor, the pressure of the working fluid discharged from each reciprocating pump is adjusted to be the same as the pressure of the coating agent being pumped from another reciprocating pump to the coating machine. Therefore, the pressure of the coating agent injected into each reciprocating pump while squeezing out the working fluid becomes the same as the pressure of the coating agent pumped to the coating machine from another reciprocating pump. Even when the reciprocating pump is switched, it is prevented that the coating agent is squeezed out at a pressure equal to the pressure of the coating agent pumped to the coating machine from other reciprocating pumps, causing a pulsating flow in the coating agent supplied to the coating machine. To be done.

〔Example〕

Hereinafter, the present invention will be described based on specific examples shown in the drawings.

FIG. 1 is a flow sheet showing an embodiment of the coating agent supply device according to the present invention.

The same parts as those in FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted.

A coating agent suction port 2a and a coating agent discharge port 2b are formed in the coating agent chamber 2 of the reciprocating pump 4A (4B), and the coating agent suction port 2a is provided with a coating agent supply source 7 via an on / off valve 6A (6B).
And the coating material discharge port 2b is connected to the coating machine 5 via an on / off valve 8A (8B).

Further, a working fluid supply / discharge port 3a is formed in the working fluid chamber 3, and a working fluid supply source 9 for supplying a working fluid at a preset constant flow rate is operated via the on / off valve 10A (10B). The return pipe 11 is connected to the fluid supply / discharge port 3a and returns the working fluid discharged from the working fluid chamber 3 to the working fluid supply source 9.
It is connected to the working fluid supply / discharge port 3a via B).

The on / off valves 10A and 10B are alternately opened and closed so that the coating agent is continuously squeezed out from the reciprocating ports 4A and 4B, and one of the on / off valves (for example, 10
The other on / off valve is opened before A) is closed so that working fluid is supplied to each reciprocating pump 4A and 4B alternately and without interruption.

The on / off valves 8A and 10A (8B and 10B) are opened and closed at substantially the same timing so that the coating agent is squeezed out from the coating agent discharge port 2b when the working fluid is being injected from the working fluid supply / discharge port 3a. , The on / off valves 6A and 12 so that the working fluid is squeezed out from the working fluid supply / discharge port 3a when the coating agent is being injected from the coating agent intake port 2a.
A (6B and 12B) are opened and closed at substantially the same timing.

Reference numeral 13 denotes a pressure sensor that detects the supply pressure P of the coating agent that is extruded from the reciprocating pumps 4A and 4B and supplied to the coating machine 5, and is a pipe line that connects the reciprocating pumps 4A and 4B to the coating machine 5. It is attached to 14.

Reference numeral 15 is a pressure control valve whose set pressure is automatically adjusted to the detected pressure P based on the pressure detection signal of the pressure sensor 13, and which supplies the working fluid discharged from the reciprocating pumps 4A and 4B to the working fluid supply source. It is placed in a return pipe 11 that recirculates to 9 and is in a closed state when the pressure on its upstream side 11a is below a set pressure, and is opened when the set pressure is reached to discharge the working fluid, By maintaining the discharge pressure of the working fluid discharged from each reciprocating pump 4A or 4B at the same pressure as the supply pressure of the coating agent pumped to the coating machine 5 from the other reciprocating pump 4B or 4A, the working fluid is discharged. The pressure of the coating agent injected into each of the reciprocating pumps 4A and 4B while being squeezed out is kept the same as the supply pressure P of the coating agent fed to the coating machine 5.

That is, when the supply pressure of the coating agent injected from the coating agent supply source 7 into each of the reciprocating pumps 4A and 4B is higher than the set pressure P, the pressure of the working fluid extruded from the reciprocating pumps 4A and 4B also increases. The pressure of the coating agent stored in the reciprocating pumps 4A and 4B is reduced to the set pressure P by increasing the opening degree of the pressure adjusting valve 15 to reduce the load applied to the working fluid.

Further, when the supply pressure of the coating agent injected from the coating agent supply source 7 into each of the reciprocating pumps 4A and 4B is lower than the set pressure P, the pressure of the working fluid discharged from the reciprocating pumps 4A and 4B also becomes lower. The pressure of the coating agent stored in the reciprocating pump is raised to a set pressure by reducing the opening of the pressure adjusting valve 15 and applying a load to the working fluid.

Reference numerals 16, 16 ... Are limit switches for operating the on / off valves at a predetermined timing.

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

First, when the on / off valves 8A and 10A are opened, the working fluid from the working fluid supply source 8 is injected into the working fluid chamber 3 of the reciprocating pump 4A at a constant flow rate, and at the same time, the working fluid from the coating agent chamber 2 is discharged. The coating agent is squeezed out at the same flow rate as the supply flow rate and sent under pressure to the coating machine 5.

Then, the supply pressure P of the coating agent that is being fed from the reciprocating pump 4A to the coating machine 5 is detected by the pressure sensor 13, and the set pressure of the pressure regulating valve 15 is based on the detection signal from the pressure sensor 13 at that time. It is automatically set to a pressure equal to the supply pressure P.

Next, when the on / off valves 6B and 12B are opened, the coating agent is injected from the coating agent supply source 7 into the coating agent chamber 2 of the reciprocating pump 4B, and at the same time, the working fluid is discharged from the working fluid chamber 3 of the reciprocating pump 4B. The working fluid is squeezed out and is returned to the working fluid supply source 9 via the pressure regulating valve 15.

At this time, the set pressure of the pressure regulating valve 15 is maintained at a pressure equal to the supply pressure P of the coating agent to the coating machine 5, and when the pressure of the extruded working fluid is higher than the set pressure, The pressure of the coating agent stored in the reciprocating pump 4B is reduced to the set pressure P by increasing the opening of the pressure adjusting valve 15 to reduce the load on the working fluid.

When the pressure of the working fluid discharged from the reciprocating pump 4B is lower than the set pressure, the opening of the pressure regulating valve 15 is reduced to apply a load to the working fluid so that the working fluid is stored in the reciprocating pump 4B. The coating agent pressure is maintained at the set pressure P.

Therefore, the pressure of the coating agent injected into the coating agent chamber 2 when the working fluid is discharged from the working fluid chamber 3 of the reciprocating pump 4B is set by the pressure regulating valve 15, that is, supplied from the reciprocating pump 4A to the coating machine 5. The supply pressure P of the coating agent is maintained, the coating agent is stored in the reciprocating pump 4B at a pressure equal to the supply pressure P, and the on / off valves 11B and 10B are closed.

Immediately before the coating agent in the coating agent chamber 2 of the reciprocating pump 4A is completely discharged, the on / off valves 8B and 10B are opened to start discharging the coating agent from the reciprocating pump 4B.

At this time, the working fluid supplied from the working fluid supply source 9 at a constant flow rate is simultaneously supplied to the working fluid chambers 3 and 3 of the reciprocating pumps 4A and 4B to apply the working fluids 2 and 2 to the coating machine 5. Although the agents are pumped at the same time, since the flow rate of the working fluid supplied from the working fluid supply source 9 is kept constant, the sum total of the flow rates of the coating agents pressed out from the coating agent chambers 2 and 2 is obtained. The pressure of the coating agent stored in the coating agent chamber 2 of the reciprocating pump 4B remains unchanged.
Since the supply pressure P of the coating agent supplied from the coating agent chamber 2 of 4A to the coating machine 5 is equal, no pulsating flow is generated even when the on / off valves 8 and 10B are opened.

Then, after completely discharging the coating agent from the coating agent chamber 2 of the reciprocating pump 4A and closing the on / off valves 8A and 10A, the on / off valves 6A and 12A are opened this time, and the reciprocating pump 4A is opened.
By setting the pressure of the working fluid extruded by the coating agent injected into the reciprocating pump 4A to the same as the supply pressure P of the coating agent pumped from the reciprocating pump 4B to the coating machine 5, the reciprocating pump 4A
The coating agent is stored in the coating agent chamber 2 at a pressure equal to the supply pressure P, and the above steps are alternately repeated to feed a fixed amount of the coating agent to the coating machine 5 without interruption and without any pulsating flow. be able to.

Thus, in this embodiment, each reciprocating pump 4A and 4B
Since the discharge pressure of the working fluid discharged from the pump is made equal to the supply pressure of the coating agent supplied from the pump of the coating machine 5 to the coating, it is of course possible to prevent the pulsating flow due to the pressure difference. That is, when the reciprocating pumps 4A and 4B are alternately switched, the working fluid can be supplied to both the reciprocating pumps 4A and 4B at the same time, so that the switching valve temporarily interrupts the supply of the working fluid. It is also possible to prevent the pulsating flow, and it is possible to reliably supply the coating agent to the coating machine 5 at a constant flow rate.

In the description of the embodiment, the double-acting reciprocating pump 4A
4 and 4B, the case where the coating agent chamber 2 and the working fluid chamber 3 are formed adjacent to each other via the diaphragm 1 has been described, but the present invention is not limited to this, and a normal double-acting cylinder may be used. Of course, for example, the double-acting reciprocating pump may be configured by connecting the pistons of two single-acting cylinders linearly arranged.

Further, not only when using the two double-acting reciprocating pumps 4A and 4B, for example, using three or more reciprocating pumps to alternately supply the working fluid to each working fluid chamber, It can also be applied to a coating agent supply device that discharges in a predetermined order.

〔The invention's effect〕

As described above, according to the present invention, the pressure sensor detects the supply pressure of the coating agent that is extruded from each reciprocating pump and sent to the coating machine, and the pressure is adjusted based on the pressure detection signal of the pressure sensor. By controlling the valve, the pressure of the working fluid discharged from each reciprocating pump is adjusted to be the same as the pressure of the coating agent being pumped from another reciprocating pump to the coating machine. However, the pressure of the coating agent injected into each reciprocating pump is the same as the pressure of the coating agent being pumped from the other reciprocating pumps to the coating machine, and even when each reciprocating pump switches, the coating from the other reciprocating pumps is applied. Since the coating agent is prevented from being squeezed out at a pressure equal to the pressure of the coating agent fed to the coating machine and causing a pulsating flow in the coating agent supplied to the coating machine, the spray amount of the coating machine and the coating pattern diameter Can change Is prevented Ku uneven paint is excellent effect that it is possible to maintain good coating quality.

[Brief description of drawings]

FIG. 1 is a flow sheet showing an embodiment of the present invention, and FIG. 2 is a flow sheet showing a coating agent supply device previously proposed by the applicant. Explanation of symbols 1 ... diaphragm, 2 ... coating agent chamber, 2a ... coating agent supply port, 3 ... working fluid chamber, 3a ... working fluid supply / discharge port, 4A, 4B ... reciprocating pump, 5 ... Coating machine, 7 ... Coating agent supply source, 9 ... Working fluid supply source, 13 ... Pressure sensor,
15 ... Pressure control valve.

Claims (1)

[Claims] 1. A diaphragm (1) or piston is actuated by a working fluid injected at a constant flow rate from one port (3a) to cause the coating agent injected from the other port (2a) to flow through the working fluid. A plurality of double-acting reciprocating pumps (4A, 4B), which are designed to output at a constant flow rate according to the above, are connected in parallel to the applicator (5), and the respective reciprocating pumps (4A, 4B) are connected. ) Are alternately operated to supply a constant amount of the coating agent to the coating machine (5) under pressure without interruption, in a coating agent supply device for detecting a supply pressure of the coating agent ( 13) is installed in the pipe line (14) for supplying the coating material from the reciprocating pumps (4A, 4B) to the coating machine (5), and based on the pressure detection signal of the pressure sensor (13), The discharge pressure of the working fluid discharged from each reciprocating pump (4A, 4B) is determined by Pressure regulating valve set to the same as the supply pressure of the coating material supplied to) (15) each reciprocating pump (4A, 4
A coating agent supply device characterized by being interposed in a return pipe line (11) for circulating a working fluid from B).