JPH02233162A - Apparatus for controlling emitting amount of spray gun - Google Patents

Abstract

PURPOSE:To always automatically keep a stable emitting amount by controlling a needle valve driving means to set a nozzle to a predetermined opening degree and controlling the emitting amount of paint through a pressure controller corresponding to a flow rate detection value. CONSTITUTION:The needle valve 46 of a spray gun 18 is driven on the basis of the signal from a control apparatus 28 through a solenoid valve 68 and, when a nozzle 44 is opened in the predetermined opening degree set by a pulse motor 52, the pressurized paint in a paint tank 14 passes through a conduit 16 to be emitted from the nozzle 44. In order to change the pressure in the paint tank 14 detected by a pressure detector 32 corresponding to the emitting paint amount detected by a flow rate detector 36, the control apparatus 28 controls the pressure of the air from a compressor 24 through an electropneumatic converter 22 as a pressure controller. By this method, an emitting amount can be kept always stably.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is a method of discharging paint from a nozzle that is connected to a paint tank via a conduit and that can be opened and closed by a needle valve, and mixing it with air near the nozzle. The present invention relates to a spray gun discharge amount control device that controls the amount of paint discharged from a spray gun that sprays paint.

[Prior art]

The discharge amount of conventional spray guns is controlled by manually adjusting the opening of the nozzle using a needle valve or by adjusting a spring-type regulator.

This adjustment procedure involves first stopping the paint discharge, that is, temporarily suspending the work, and then adjusting the discharge amount by operating the needle valve or regulator based on experience and intuition based on the condition of the paint finish, etc. .

However, this kind of adjustment varies depending on the operator and is not accurate. Furthermore, it is nearly impossible to quickly and accurately adjust the viscosity of the paint due to changes in the outside air or the temperature of the paint itself. Furthermore, since the needle valve or regulator is manually adjusted to reduce pressure loss due to paint build-up, accuracy is poor. Furthermore, manual adjustment of the needle valve results in rough control, so to check the discharge amount, either stop the painting operation and actually measure the discharge amount, or, if the painting operation is not interrupted, measure the discharge amount on the object to be coated. The attached liquid film must be measured wet, which has poor accuracy. Therefore, in order to improve accuracy, it is necessary to dry the adhered liquid film before performing actual measurements.

Another conventional example is one that is equipped with both the needle valve adjustment and the regulator adjustment, one of which is fixed and the other is automatically controlled. As a result, the discharge amount can be adjusted without relying on the experience or intuition of the operator, improving accuracy and workability.

[Problem to be solved by the invention]

However, the above-mentioned control cannot prevent paint build-up, and the responsiveness and control accuracy are not precise, so operator monitoring is always required and unmanned operation is not possible. Further, at the start of work, it is necessary to manually set either the opening of the nozzle using the needle valve or the pressure in the paint tank, which makes the work complicated. This kind of work is
For example, since it is also required when restarting a painting operation after it has been temporarily interrupted, the amount of paint discharged may fluctuate before and after the temporary interruption, which will have an adverse effect on the coating of the object to be coated.

Furthermore, if the temperature changes during one day's work, the viscosity of the paint changes due to the temperature change. Especially at the start of work (generally in the morning)
In this case, the temperature is low and the paint viscosity is high, but as the temperature rises over time and the paint viscosity decreases, the discharge amount will increase more than the initial discharge amount.

Such an increase in the discharge amount increases the thickness of the coating on the object to be coated, which causes defects.

Furthermore, if a paint with poor dispersibility is used, deposits will be generated and pressure loss will occur even when there is little temperature change, and in such a case, the discharge amount will decrease. For this reason, the film thickness of the coating on the object to be coated decreases, causing defects.

In consideration of the above-mentioned facts, the present invention aims to provide a spray gun discharge rate control system that can automatically maintain a stable discharge rate at all times without requiring operator supervision.

In addition to the above object, another object of the present invention is to obtain a spray gun discharge amount control device that can obtain a stable discharge amount before and after the interruption of a painting operation.

[Means to solve the problem]

In the invention described in claim (1), the paint is discharged from a nozzle that is connected to the paint tank via a conduit and can be opened and closed by a needle valve, and the paint is mixed with air near the nozzle and sprayed from a spray gun. A spray gun discharge amount control device that controls the amount of paint discharged, the device comprising: a needle valve driver that drives the needle valve to change the opening degree of the nozzle; and a pressure controller that controls the pressure in the paint tank. , a flow rate detector for detecting the flow rate of the paint flowing in the conduit, and controlling the needle valve driving means to make the nozzle a predetermined opening degree, and controlling a pressure controller in accordance with the detected value by the flow rate detector. and control means for controlling the amount of paint discharged from the nozzle.

The invention according to claim (2) is characterized in that the pressure controller controls the needle valve driving means to increase the opening degree of the nozzle when the pressure in the paint tank exceeds a predetermined value. .

The invention according to claim (3) is characterized in that the nozzle is provided with a holding means for holding the pressure in the paint tank at the pressure immediately before the nozzle is closed when the nozzle is closed by the needle valve.

[Effect]

When the needle valve is driven and the nozzle is opened to a predetermined opening degree, the paint tank is pressurized, so paint is discharged from the nozzle through the conduit.

This discharge amount is detected by a flow rate detector, and the control means controls a pressure controller according to this detected value to change the pressure in the paint tank. For example, if the detected value is higher than the desired ejection amount, the ejection amount can be reduced by lowering the pressure inside the paint tank, and the desired ejection amount can be achieved. Furthermore, when the detected value is lower, the discharge amount is increased by increasing the pressure in the paint tank, and the desired discharge amount can be achieved.

In this way, since the pressure in the paint tank is controlled to control the amount of paint discharged from the nozzle, the control is precise and a stable amount of discharge can be obtained. Furthermore, since the actual flow rate is detected, responsiveness to temperature changes, deposition, etc. is good, and accuracy is improved.

In the invention of claim (2), not only the pressure inside the coating tank is controlled, but the opening degree of the nozzle by the needle valve is adjusted. In other words, when the opening degree of the nozzle is stable and the pressure is controlled while maintaining the opening degree, if the pressure is constantly increased due to paint accumulation etc. and exceeds a predetermined pressure, the needle valve driving means is controlled. to drive the needle valve and increase the opening of the nozzle. As a result, the discharge amount increases, so that the pressure can be reduced by the amount of this increase in the discharge amount. In this way, by controlling the amount of paint discharged by both the pressure inside the painting tank and the opening degree of the nozzle, a stable amount of paint can be obtained and an excessive increase in pressure inside the painting tank can be prevented. Can be done.

In the invention of claim (3), when the painting work is temporarily interrupted, the pressure in the painting tank before the interruption is maintained, so when the painting work is restarted, the painting can be done immediately under the same conditions as before the interruption. It can be performed.

〔Example〕

FIG. 1 shows a spray gun discharge control device 1 according to this embodiment.
The schematic structure of 0 is shown.

A paint tank 14 in which paint 12 is stored is sealed, and a conduit 16 is connected from the upper end of the paint tank 14.
is inserted. The opening at the tip of the conduit 16 is located near the bottom of the paint tank 14 , and pressurization within the paint tank 14 causes the paint 12 to be sent into the conduit 16 and guided to the spray gun 18 . There is.

The interior of the paint tank 14 is pressurized by an electro-pneumatic converter 22 as a pressure controller, which is communicated with the interior of the paint tank 14 via an air supply pipe 20. This electro-pneumatic converter 22 is in communication with a compressor 24, and air can be sent into the paint tank 14 by opening and closing a valve (not shown). The compressor 24 is controlled by a pressure regulating valve (not shown) so that air can always be supplied at a constant pressure.

The valve is actuated by an electric signal from the control device 28, so that the internal pressure of the paint tank 14 can be controlled in response to the electric signal from the control device 28.

The pressure within the paint tank 14 is adapted to be detected by a pressure sensor 32 mounted via a pressure conduit 30. The value detected by the pressure detector 32 is A
The signal is supplied to the control device 28 via the /D converter 34.

A flow rate detector 36 is interposed in the middle of the conduit 16 to detect the flow rate of paint flowing from the paint tank 14 to the spray gun 18. The value detected by this flow rate detector 36 is transmitted to the A/D converter 38.
The signal is supplied to the control device 28 via. A desired flow rate is stored in a memory (not shown) of the control device 28, and a signal is output to the electro-pneumatic converter 22 according to the difference between the desired flow rate and the detected flow rate. . Note that this desired flow rate is determined by the control device 2.
This is performed by key operations on a keyboard 40 connected to 8. Note that the keyboard 40 is provided with a main switch, a start switch, an interrupt switch, a resume switch, and a control mode selection switch.

In addition, the memory of the control device 28 stores a map of the nozzle opening degree according to the flow rate (see Fig. 7) and a map of the pressure in the paint tank 14 according to the flow rate (see Fig. 8). According to the flow IQB set using the keyboard 40, the nozzle opening degree or the internal pressure of the paint tank 14 can be set.

As shown in FIG. 2, the spray gun 18 has a small diameter nozzle 44 formed at the tip of a casing 42, and a tip of a needle valve 46 is disposed correspondingly inside the casing 42. The conduit 16 is piped around the circumferential surface of the casing 42, and the paint sent from the conduit 16 is passed through the nozzle 44.
It is designed to be ejected from.

Further, an air cap 48 is placed near the nozzle 44, and a pressure regulating valve 45 is connected to the compressor 24.
A predetermined amount of atomized air is sent into the vicinity of the nozzle via the solenoid valve 47. That is, the paint ejected from the nozzle 44 is mixed with the atomized air when the solenoid valve 47 is open, and thereby becomes atomized.

The needle valve 46 is pivotally supported at its intermediate portion in a through hole 54 formed by the casing 42, and is movable axially. That is, when the needle valve 46 is axially moved in the eight directions of the arrows in FIG. 2, the nozzle 44 is closed, and when the needle valve 46 is axially moved in the opposite direction of the arrow A in FIG. 2, the nozzle 44 is opened.

An enlarged diameter portion 58 is formed at the base of the needle valve 46 so as to have the same diameter as the inner peripheral diameter of the cylinder portion 56.
6 is divided into two rooms. Hereinafter, the chamber on the bottom 60 side will be
It will be referred to as a chamber 62, and the chamber on the side of the through hole 54 will be referred to as a second chamber 64.

A compression coil spring 66 is interposed between the enlarged diameter portion 58 in the first chamber 62 and the bottom portion 60 of the casing 42, and urges the enlarged diameter portion 58 to move axially in the direction of arrow A in FIG. . Therefore, normally, the urging force of the compression coil spring 66 causes the needle valve 46 to close the opening of the nozzle 44.

On the other hand, the second chamber 64 is communicated with the compressor 24 via a pressure regulating valve 67 and a solenoid valve 68. The solenoid valve 68 is connected to the control device 28 via a driver 70, and receives ON/OFF signals from the control device 28.
The solenoid valve 68 (not shown) is opened and closed by the off signal. Here, when an ON signal is output from the control device 28 and the solenoid valve 68 is opened, air is guided from the combustor 24 to the second chamber 64. The second
The pressing force of the enlarged diameter portion 58 due to the pressure applied to the chamber 64 is set to be stronger than the urging force of the compression coil spring 66, and as a result, the nozzle 44 is opened by the on/off signal from the control device 28. The degree can be changed.

A through hole 72 is provided in the bottom 60 of the casing 42 , and a needle valve adjusting shaft 74 is supported therein, and the tip thereof is accommodated in the first chamber 62 . A male thread 76 is formed at the base of the needle valve adjustment shaft 74, and is screwed into a female thread 80 formed on the rotating member 78. The rotating member 78 is fixed in its axial movement and is rotated by the pulse motor 82 . The pulse motor 82 is connected to the control device 28 via a driver 84, and is connected to the control device 28 via a driver 84.
It is designed to be rotated according to the number of pulses from 8. When the rotating member 78 is rotated, the needle valve adjustment shaft 74
The needle valve 46 can be moved axially, and the enlarged diameter part 58 can be supported at its tip, so that the needle valve 46 can be stopped at a predetermined position regardless of the pressing force of the enlarged diameter part 58 due to the pressure of the second chamber 64. It looks like this. The rotation of the pulse motor 82 is driven in units of a predetermined number of pulses, and the position of the tip of the needle valve adjusting shaft is changed in multiple stages.

The operation of this embodiment will be explained below with reference to the flowcharts of FIGS. 3 to 6.

First, the main routine shown in FIG. 3 will be explained. It is assumed that the compressor 24 has already been driven and pressurized. In step 154, a control mode is selected by operating keys on the keyboard 40. In this embodiment, control programs are stored in advance for mode A, which only controls pressure, and mode B, which uses both needle valve opening control and pressure control, and one of these is selected. In step 156, the selected mode is determined and the selected mode is A.
In the case of mode, the process moves to step 158, and in the case of B mode, the process moves to step 160. Note that control of each mode will be described later.

When the control in step 158 or step 160 is completed, the process moves to step 162 and the nozzle 44 of the spray gun 18 is closed by the needle valve 46.

Next, pressure control in mode A will be explained according to the flowchart in FIG.

In step 200, a desired flow rate Ω is set, and in step 202, the opening degree of the needle valve 46 corresponding to the flow rate QB is read from the flow rate one-degree characteristic diagram in FIG. Set once. This needle valve 4
The opening degree of No. 6 is constant without being changed in the A mode.

In the next step 204, when the start switch is operated by key operation on the keyboard 40, the process moves to step 206, the solenoid valve 68 is opened, and the second chamber 64 in the casing 42 is pressurized. As a result, the enlarged diameter portion 58 is moved by the pressure in the second chamber 64 in the eight direction opposite to the arrow in FIG. Nozzle 44
can be opened.

When the nozzle 44 is opened in step 206, the process moves to step 208, and the flow rate O of the paint flowing in the conduit 16 is detected by the flow rate detector 36. Next, the process moves to step 210, where the set flow rate QB and the detected flow rate Q, are compared, and Q
If 8≠Q, the process moves to step 212 and the pressure P is determined based on the difference in these flow rates. , is calculated. In the next step 218, the electro-pneumatic converter 22 is activated. After controlling so that =P, the process moves to step 220.

Note that in step 210, QB=Q. If it is determined that this is the case, the process moves to step 220.

In step 220, it is determined whether or not the interrupt switch on the keyboard 40 has been operated. If it is determined that the interrupt switch has been operated, the process moves to step 222, where interruption control is performed, and then the process moves to step 224.

Note that this interruption control will be described later. Step 22
If it is determined at 0 that the interrupt switch has not been operated, step 222 is skipped and the process proceeds to step 224. In step 224, it is determined whether the end switch has been imitated, and if it has not been operated, step 224
Go to step 8 and repeat the above steps. If the end switch is imitated, this routine ends and the process moves to step 162 of the main routine (see FIG. 3).

Next, B mode control will be explained according to the flowchart of FIG.

First, in step 250, a time T indicating the discharge amount stability is set, and the process proceeds to step 251, where the allowable pressure α is set, and then the process proceeds to step 252. In step 252, the desired flow rate q is set, and then in step 2
At step 54, pressures P and l are set according to the flow rate Q from the flow rate-pressure characteristic diagram of FIG. 8, and the process moves to step 256. When the start switch is operated by operating a key on the keyboard 40 in step 256, the process moves to step 258 and the nozzle 44 is opened. The procedure for opening the nozzle 44 is the same as in the case of the A-mode control, so a detailed explanation will be omitted.

When the nozzle 44 is opened in step 258, the process moves to step 260, where the needle valve opening control is stopped when FB-α≦P, ≦PB+α, and then, in step 262, the pressure inside the paint tank 14 is detected by the pressure detector 32. Ps is detected, and the process moves to step 264 to determine that PB>α≦P,≦PB
+α determines whether or not the beans are mature. Step 264
If a negative determination is made in step 266, the pulse motor 82 is driven in accordance with the difference between them, and the rotating member 78 is rotated. Due to the rotation of this rotating member 78,
The needle valve adjustment shaft 74 is axially moved, and the needle valve 46 is axially moved accordingly, so that the opening degree of the nozzle 44 can be adjusted (needle valve opening control).

When the opening degree adjustment of the needle valve 46 is completed, step 27
Transition to 0. Further, if the determination in step 264 is affirmative, the timer Ts is started in step 269 and the timer Ts is started in step 270 only if the previous determination was not established in step 268.
Move to. If it was established last time, step 269 is skipped. In step 270, it is determined whether the timer T, or TB has reached. If the timer T, or TB has not been reached, it is determined that the paint discharge flow rate is unstable, and the process moves to step 272. Also, in step 270, T, or T
If it is determined that Il has been reached, the opening degree of the needle valve 46 is constant, the paint discharge flow rate is stable, and the paint tank 2
It is determined that the pressure inside 2 has stabilized at the desired pressure PR, and the process moves to step 274.

In step 272, it is determined whether or not the interruption switch has been operated by a key operation on the keyboard 40. If it is determined that a copy has been made, the process proceeds to step 276, where interruption control is performed, and then the process proceeds to step 278. Note that this interruption control will be described later.

If it is determined in step 272 that the interrupt switch has not been operated, step 276 is skipped and the process proceeds to step 278. In step 278, it is determined whether the end switch has been operated, and if it has not been operated, the process moves to step 260 and the above steps are repeated. Also,
If the end switch is operated, this routine ends and the process moves to step 162 of the main routine (see FIG. 3).

Further, when the process moves from step 270 to step 274, the process switches to pressure control, clears the variable I in step 274, moves to step 280, detects the flow rate Q5 by the flow rate detector 36, and then moves to step 282. Then, the set flow rate Q and the detected flow rate Qs are compared.

In step 282, Q. f-Q. If it is determined that this is the case, the process moves to step 290, and the pressure P is determined based on the difference in these flow rates. Calculate. In the next step 292, the pressure detector 32 detects the actual pressure P in the paint tank l4, and the process moves to step 294. In step 294, the detected pressure P, is determined to be the maximum allowable pressure PXAX in the paint tank 14.
If it is determined that Ps ≧P)IAX, it is necessary to increase the opening degree of the needle valve 46 to lower the pressure inside the paint tank 14, so the process proceeds to step 272. Then, the control shifts to needle valve opening control.

If it is determined in step 294 that PS<PMAX, the process proceeds to step 298 where the electro-pneumatic converter 22 is operated to control so that PC=ps, and then step 3
Transition to 00. Note that if it is determined in step 282 that QB=QS, the process moves to step 300.

In step 300, it is determined whether or not the interrupt switch on the keyboard 40 has been operated. If it is determined that the interrupt switch has been operated, the process moves to step 302, where interruption control is performed, and then the process moves to step 304.

Note that this interruption control will be described later. Step 30
If it is determined at 0 that the interrupt switch has not been operated, step 302 is skipped and the process proceeds to step 304. In step 304, it is determined whether the end switch has been operated, and if it has not been operated, step 28
0 and repeat the above steps. If the end switch is operated, this routine ends and the process moves to step 162 of the main routine (see FIG. 3).

Next, the interruption control routine will be explained according to the flowchart of FIG.

Step 220 in A mode (see Figure 4), Step 272 or Step 300 in B mode (see Figure 5)
When the interrupt switch is operated at step 350, Q,l is first substituted for Q, and then, at step 354, nozzle 4 is
Close 4. As a result, the paint discharge is temporarily interrupted, and the process moves to step 362.

In step 362, it is determined whether the restart switch has been operated by key operation on the keyboard 40, and if the determination is negative, the process moves to step 350 and the above steps are repeated.

Thereby, the pressure in the paint tank 14 can be maintained at the pressure before the interruption. If an affirmative determination is made in step 362, the process proceeds to step 364, where the nozzle 44 is opened again, and the process returns to the next step after the step to which it has been transferred.

In this way, in this embodiment, the control of the paint discharge flow rate is
In the mode control, the pressure inside the paint tank 14 is controlled according to the actual flow rate, so it can be controlled more accurately than the discharge flow rate control using the needle valve 46. In addition, it can respond to changes in flow rate due to temperature changes and paint buildup, so it is possible to perform stable painting work without causing uneven paint film thickness on the object to be painted. .

In addition, in the case of B mode control, rough control is performed by adjusting the opening degree of the needle valve 46, and the switch to pressure control is made when the paint discharge flow rate is stabilized to some extent, so preparations are made until the desired discharge flow rate is achieved. Work time can be shortened. In addition, if the discharge flow rate decreases due to temperature changes or paint accumulation, the pressure will be gradually increased accordingly, but if the pressure exceeds a predetermined value, the opening of the needle valve 46 will be increased again. Since it is possible to switch to adjustment control, the pressure in the paint tank 14 does not rise excessively, and safety is high.

Furthermore, the spray gun discharge control device 10 according to this embodiment
In this case, when the painting work is temporarily interrupted, the pressure in the paint tank 14 before the interruption can be maintained, so when the painting work is restarted, the paint is immediately sprayed at the same discharge flow rate as before the interruption. This improves work efficiency.

In this embodiment, the maps shown in FIGS. 7 and 8 are stored in the memory of the control device 28, and the nozzle opening and tank pressure are automatically set according to the flow rate. It may also be set manually by a person. Further, in this embodiment, the needle valve adjustment shaft 74 is moved by a pulse motor 82.
However, the rotation of the needle valve adjustment shaft 74 may be visually determined by an operator, and the needle valve adjustment shaft 74 may be rotated by a predetermined amount.

〔Effect of the invention〕

As explained above, the spray gun discharge rate control device according to the present invention has the excellent effect of automatically maintaining a stable discharge rate without requiring operator supervision.

In addition to the above effects, there is also the effect of being able to obtain a stable discharge amount before and after the interruption of the painting operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the spray gun discharge control device according to the present embodiment, FIG. 2 is a sectional view showing the internal structure of the spray gun, FIG. 3 is a flowchart showing the main routine of paint discharge control, and FIG. Figure 5 is a flowchart showing the A mode control routine, Figure 5 is a flowchart showing the B mode control routine, Figure 6 is a flowchart showing the painting interruption control routine, Figure 7 is a flow rate-nozzle opening characteristic diagram, and Figure 8 is a flowchart showing the B mode control routine.
The figure is a flow rate-pressure characteristic diagram. 10... Spray gun discharge rate control device, 12... Paint, 14... Paint tank, 16... Conduit, 18... Spray gun, 22... Electro-pneumatic converter, - Control device,・Pressure detector, ・Flow rate detector, ・Nozzle, ・Needle valve.

Claims (3)

[Claims] (1) A sprayer that controls the amount of paint discharged from a spray gun that discharges paint from a nozzle that is connected to a paint tank via a conduit and can be opened and closed by a needle valve, and mixes it with air near the nozzle to atomize the paint. The gun discharge amount control device includes a needle valve driving means for driving the needle valve to change the opening degree of the nozzle, a pressure controller for controlling the pressure in the paint tank, and a flow rate of paint flowing in the conduit. a flow rate detector for detecting the flow rate, and controlling the needle valve driving means to open the nozzle at a predetermined degree, and controlling a pressure controller according to the detected value by the flow rate detector to discharge paint from the nozzle. A spray gun discharge amount control device having a control means for controlling the amount. (2) Claim (1) characterized in that the pressure controller controls the needle valve driving means to increase the opening degree of the nozzle when the pressure in the paint tank exceeds a predetermined value.
) Spray gun discharge rate control device. (3) The spray gun according to claim (1), further comprising a holding means for maintaining the pressure in the paint tank at the pressure immediately before the nozzle is closed when the nozzle is closed by a needle valve. Discharge rate control device.