JP2694997B2 - Spray gun discharge rate control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a paint which is discharged from a nozzle which is connected to a paint tank through a conduit and which can be opened and closed by a needle valve and which is mixed with air in the vicinity of the nozzle. The present invention relates to a spray gun discharge amount control device for controlling the discharge amount of paint from a spray gun for spraying.

(Prior art)

To control the discharge amount in a conventional spray gun, the opening degree of the nozzle is manually adjusted by a needle valve, or a spring type regulator is adjusted. This adjustment procedure is
First, the discharge of the paint is temporarily stopped, that is, the work is temporarily stopped, and then the worker adjusts the discharge amount by operating the needle valve or the regulator based on experience and intuition based on the finish of the coating.

However, in such adjustment, the accuracy varies depending on the operator who operates it. In addition, it is almost impossible to quickly and accurately adjust the change in the paint viscosity due to the change in the temperature of the outside air or the paint itself. Further, in the pressure loss due to the accumulation of the paint system, the accuracy is poor because the needle valve or the regulator is likewise manually adjusted. In addition, the manual adjustment of the needle valve is a coarse control, so when confirming the discharge rate, interrupt the coating work and measure the discharge rate, or if the coating work is not interrupted, The adhesion liquid film must be measured with a wet, and the accuracy is poor. Therefore, in order to improve accuracy, it is necessary to measure the attached liquid film after drying it.

Further, as another conventional example, there is one in which both the adjustment of the needle valve and the adjustment of the regulator are provided, and one of them is fixed and the other is automatically controlled. As a result, the discharge amount can be adjusted without relying on the experience and intuition of the worker, and accuracy and workability are improved.

[Problems to be solved by the invention]

However, the control as described above cannot prevent the coating material from accumulating, and the responsiveness and the control accuracy are not high. Therefore, it is always necessary to monitor the worker and it is impossible to unmanned. In addition, since either the opening of the nozzle by the needle valve or the pressure in the paint tank must be manually set at the start of work, the work becomes complicated. Such work is required, for example, when the painting work is temporarily interrupted and then restarted.Therefore, the discharge amount of the paint may change before and after the interruption, which may adversely affect the painting of the object to be coated. Will be given.

Furthermore, if a temperature change occurs during a day's work, the viscosity of the paint changes due to the temperature change. In particular, at the beginning of work (generally in the morning), the temperature is low and the viscosity of the coating is high, but the temperature rises over time and the viscosity of the coating decreases, so the discharge amount is higher than the initial discharge amount. Such an increase in the discharge amount increases the film thickness of the coating on the object to be coated, which causes a defect.

Further, when a coating material having poor dispersibility is applied, deposits are generated and pressure loss occurs even when the temperature change is small, and in such a case, the discharge amount is reduced. Therefore, the film thickness of the coating on the object to be coated decreases,
Failure to do so.

In consideration of the above facts, an object of the present invention is to obtain a spray gun discharge amount control device which can automatically maintain a stable discharge amount without requiring the monitoring of an operator.

Further, in addition to the above objects, it is an object to obtain a spray gun discharge amount control device capable of obtaining a stable discharge amount before and after the interruption of the coating work.

[Means for solving the problem]

In the invention according to claim (1), the paint is discharged from a nozzle that is connected to the paint tank through a conduit and can be opened and closed by a needle valve, and is mixed with air in the vicinity of the nozzle to spray the paint. A spray gun discharge amount control device for controlling a discharge amount of paint, comprising: a needle valve drive means for driving the needle valve to change an opening of a nozzle; and a pressure controller for controlling a pressure in the paint tank, A flow rate detector that detects the flow rate of the paint flowing in the conduit, and the needle valve drive means to control the nozzle to a predetermined opening degree and to control the pressure controller according to the value detected by the flow rate detector. Control means for controlling the discharge amount of the paint from the nozzle.

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

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

[Action]

When the needle valve is driven and the nozzle is opened at a predetermined opening, the paint tank is pressurized so that the paint is discharged from the nozzle through the conduit. This discharge amount is detected by the flow rate detector, and the control means controls the pressure controller according to the detected value to change the pressure in the paint tank. For example, when the detected value is higher than the desired discharge amount, the discharge amount can be reduced to a desired discharge amount by lowering the pressure in the paint tank. Further, 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 obtained.

In this way, since the pressure in the paint tank is controlled to control the discharge amount from the nozzle, the control becomes dense and a stable discharge amount can be obtained. In addition, since the actual flow rate is detected, the responsiveness and the accuracy are improved even with respect to temperature changes and accumulation. In the invention of claim (2), not only the pressure in the coating tank is controlled, but the opening degree of the nozzle by the needle valve is adjusted. That is, when the opening of the nozzle is stable and the pressure is controlled while maintaining the opening, the needle valve drive means is controlled when the pressure is constantly increased due to paint deposition or the like and becomes equal to or higher than a predetermined pressure. Then, the needle valve is driven to increase the opening of the nozzle. This allows
Since the discharge amount increases, the pressure can be reduced by the increase in the discharge amount. In this way, by controlling the discharge amount of the paint by both the pressure in the coating tank and the opening of the nozzle, it is possible to obtain a stable discharge amount and prevent an excessive increase in pressure in the coating tank. You can

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 resumed, the immediate painting work is performed under the same conditions as before the interruption. It can be performed.

〔Example〕

FIG. 1 shows a spray gun discharge control device according to this embodiment.
10 schematic structures are shown.

The paint tank 14 in which the paint 12 is accumulated is sealed,
A conduit 16 is inserted into the paint tank 14 from its upper end surface. The tip opening portion of the conduit 16 is arranged near the bottom surface of the paint tank 14, and by the pressure inside the paint tank 14,
The paint 12 is fed into the conduit 16 and guided to the spray gun 18.

Pressurization in the paint tank 14 is connected to the interior of the paint tank 14 via the air supply pipe 20 as an electro-pneumatic converter as a pressure controller.
Made by 22. The electro-pneumatic converter 22 is in communication with the 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 adjusting valve (not shown) so that the air can be constantly supplied at a constant pressure.

The valve is adapted to be activated by an electric signal from the control device 28, whereby the paint tank 14 can be controlled in its internal pressure according to the electric signal from the control device 28.

The pressure in the paint tank 14 is detected by a pressure detector 32 attached via a pressure conduit 30. The value detected by the pressure detector 32 is supplied to the control device 28 via the A / D converter 34.

A flow rate detector 36 is provided in the middle of the conduit 16 to detect the flow rate of the paint flowing from the paint tank 14 to the spray gun 18. The value detected by the flow rate detector 36 is supplied to the control device 28 via the A / D converter 38. Controller 28
A desired flow rate is stored in a memory (not shown), 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.
The desired flow rate is set by operating the keyboard 40 connected to the control device 28.
The keyboard 40 is provided with a main switch, a start switch, an interruption switch, a restart switch, and a control mode selection switch.

The memory of the controller 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). Therefore, the nozzle opening or the paint tank 14 internal pressure can be set in accordance with the flow rate Q _B set by the keyboard 40.

As shown in FIG. 2, the spray gun 18 has a nozzle 42 having a small diameter formed at the tip of a casing 42.
The tip portion of the needle valve 46 is correspondingly arranged inward of 42. On the peripheral surface of the casing 42, the conduit 16 is piped,
The paint sent from the conduit 16 is ejected from the nozzle 44.

An air cap 48 is covered in the vicinity of the nozzle 44, and a predetermined amount of atomized air is sent from the compressor 24 to the vicinity of the nozzle via the pressure adjusting valve 45 and the solenoid valve 47. That is,
The paint ejected from the nozzle 44 is atomized by being mixed with this atomized air when the solenoid valve 47 is open.

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

An expanded 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, and the cylinder portion 56 is divided into two parts.
It is divided into rooms. Hereinafter, the chamber on the bottom 60 side is referred to as a first chamber 62, and the chamber on the through hole 54 side is referred to as a second chamber 64.

A compression coil spring 66 is interposed between the enlarged diameter portion 58 of the first chamber 62 and the bottom portion 60 of the casing 42, so
It is biased so as to axially move in the direction of arrow A in the figure. Therefore, normally, the biasing 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 has a pressure adjusting valve 67 and a solenoid valve.
It communicates with the compressor 24 through 68. The solenoid valve 68 is connected to the control device 28 via a driver 70, and a valve (not shown) of the solenoid valve 68 is opened / closed by an on / off signal from the control device 28. Here, when the ON signal is output from the control device 28 and the valve of the solenoid valve 68 is opened, the air is guided from the compressor 24 to the second chamber 64.
The pressing force of the expanded diameter portion 58 by the pressure applied to the second chamber 64 by the compressor 24 is set stronger than the biasing force by the compression coil spring 66, and as a result, the control device 28
The opening degree of the nozzle 44 can be changed by an on / off signal from.

A through hole 72 is provided in the bottom portion 60 of the casing 42, a needle valve adjusting shaft 74 is pivotally supported, and the tip portion thereof is housed in the first chamber 62. A male screw 76 is formed on the base of the needle valve adjusting shaft 74, and is screwed with a female screw 80 formed on the rotating member 78. The rotation member 78 has its axial fluctuation fixed, and is rotated by the pulse motor 82. The pulse motor 82 is a control device via a driver 84.
It is connected to 28 and is rotated according to the number of pulses from the control device 28. When the rotating member 78 is rotated,
The needle valve adjusting shaft 74 can be axially moved, and the tip end portion of the needle valve adjusting shaft 74 supports the expanded diameter portion 58, so that the needle valve 46 can be moved at a predetermined position regardless of the pressing force of the expanded diameter portion 58 due to the pressure of the second chamber 64. It can be stopped. The rotation of the pulse motor 82 is driven in a predetermined pulse number unit, and the tip position of the needle valve adjusting shaft is changed in a plurality of steps.

The operation of this embodiment will be described below with reference to the flow charts of FIGS.

First, the main routine of FIG. 3 will be described. Note that the compressor 24 is already driven and pressurized. In step 154, the control mode is selected by operating the keyboard 40. In the present embodiment, the control programs for the A mode only for pressure control and the B mode for combined use of needle valve opening control and pressure control are stored in advance, and any one of them is selected. In step 156, the selected mode is discriminated, and if the selected mode is the A mode, the process proceeds to step 158, and if it is the B mode, the process proceeds to step 160. The 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 moved.
Is closed by the needle valve 46.

Next, the pressure control in the A mode will be described with reference to the flow chart of FIG.

At step 200, a desired flow rate Q _B is set, then at step 202, the opening of the needle valve 46 corresponding to the flow rate Q _B is read from the flow rate-opening characteristic diagram of FIG. 7, and the read predetermined value is read. Set to the opening. The opening degree of the needle valve 46 does not change in the A mode and is constant.

When the start switch is operated by the key operation of the keyboard 40 in the next step 204, the process proceeds to step 206,
The valve of the solenoid valve 68 is opened, and the second chamber 64 inside the casing 42 is pressurized. As a result, the expanded diameter portion 58 becomes the second chamber.
The pressure of 64 causes the compression coil spring 66 to move in the direction opposite to the arrow A in FIG. 2 against the urging force of the compression coil spring 66, the tip of the needle valve 46 is separated from the nozzle 44, and the nozzle 44 can be opened.

When the nozzle 44 is opened at step 206, the flow goes to step 208 to detect the flow rate Q _S of the paint flowing through the conduit 16 from the flow rate detector 36. Next, in step 210, the set flow rate Q _B and the detected flow rate Q _S are compared, and if Q _B ≠ Q _S , step 212 is entered and the pressure P _C is determined based on the difference between these flow rates.
Is calculated. In the next step 218, the electro-pneumatic converter 22 is operated to control P _C = P _S, and then the step 220 is executed.
Move to. If it is determined in step 210 that Q _B = Q _S , the process proceeds to step 220.

In step 220, it is judged whether or not the interruption switch on the keyboard 40 has been operated. If it is judged that the interruption switch has been operated, the operation proceeds to step 222 to perform interruption control and then to step 224. The interruption control will be described later. If step 220 determines that the interrupt switch has not been operated, step 222 jumps to step 224. In step 224, it is judged whether or not the end switch has been operated. If not, the process proceeds to step 208 and the above steps are repeated. When the end switch is operated, this routine ends, and the routine proceeds to step 162 of the main routine (see FIG. 3).

Next, the B mode control will be described with reference to the flow chart of FIG.

First, in step 250, the time T _B indicating the discharge amount stability is set, the process proceeds to step 251 to set the allowable pressure α, and then the process proceeds to step 252. Set the step 252 the desired flow rate Q _B, then the flow of Figure 8 at step 254 - proceeds to step 256 to set the pressure P _B in accordance with the flow rate Q _B from the pressure characteristic diagram. Keyboard 40 at step 256
When the start switch is operated by the above key operation,
The process moves to step 258 and the nozzle 44 is opened. Nozzle 4
The opening procedure of 4 is the same as that in the case of the above A mode control, and thus detailed description will be omitted.

When nozzle 44 is opened at step 258, step 260
Then, the needle valve opening control is stopped at P _B −α ≦ P _S ≦ P _B + α, and at step 262, the pressure detector 32 detects the pressure P _S in the paint tank 14 and the process proceeds to step 264. Then, it is determined whether or not P _B > α ≦ P _S ≦ P _B + α holds. When a negative determination is made in step 264, the process proceeds to step 266, the pulse motor 82 is driven according to the difference, and the rotating member 78 is rotated. The rotation of the rotating member 78 causes the needle valve adjusting shaft 74 to move axially,
According to this, the needle valve 46 is axially moved, and the opening degree of the nozzle 44 can be adjusted (needle valve opening degree control).

When the needle valve 46 opening adjustment is completed, step 270
Move to. If the result of step 264 is affirmative, step 268 is executed only if the previous time is not satisfied.
Then, the timer T _S is started and the process proceeds to step 270. If yes, skip step 269. In step 270 it is determined whether a timer T _S or T _B, if not reached T _S or T _B, it is determined that the discharge amount of paint is unstable, the process proceeds to step 272. If it is determined in step 270 that T _S or T _B has been reached, the needle valve 46 has a constant opening, the paint discharge flow rate is stable, and the pressure in the paint tank 22 reaches the desired pressure P _B. It is judged to be stable, and the process proceeds to step 274.

In step 272, it is judged whether or not the interruption switch is operated by the key operation of the keyboard 40. If it is judged that the interruption switch is operated, the processing proceeds to step 276, and the interruption control is performed, and then the processing proceeds to step 278. The interruption control will be described later. If step 272 determines that the interrupt switch has not been operated, step 276 jumps to step 278. In step 278, it is judged whether or not the end switch has been operated. If not, the process proceeds to step 260 and the above steps are repeated. If the end switch is operated, this routine ends, and the main routine (see FIG. 3) step 162 is executed.
Move to.

Further, when the step 270 shifts to the step 274, the pressure control is switched to clear the variable I in the step 274, and then the flow shifts to the step 280 to detect the flow rate Q _S by the flow rate detector 36, and then the step 282. Then, the set flow rate Q _B is compared with the detected flow rate Q _S.

When it is determined in step 282 that Q _B ≠ Q _S , the process proceeds to step 290, and the pressure P _C is calculated based on the difference between these flow rates. At the next step 292, the actual pressure P _S in the paint tank 14 is detected by the pressure detector 32, and the process proceeds to step 294. In step 294, the detected pressure P _S is the paint tank.
It is judged whether or not the maximum allowable pressure P _MAX within 14 is reached,
If it is determined that P _S ≧ P _MAX , it is necessary to increase the opening degree of the needle valve 46 to reduce the pressure in the paint tank 14, so the process proceeds to step 272 and the needle valve opening degree control is performed.

If it is determined in step 294 that P _S <P _MAX ,
Step 298 is proceeded to, and the electro-pneumatic converter 22 is operated to set P _C
After controlling so that = P _S , the process proceeds to step 300.
If it is determined in step 282 that Q _B = Q _S , the process proceeds to step 300.

In step 300, it is determined whether or not the interruption switch on the keyboard 40 has been operated. If it is determined that the interruption switch has been operated, the operation proceeds to step 302 to perform interruption control and then to step 304. The interruption control will be described later. If step 300 determines that the interrupt switch has not been operated, step 302 jumps to step 304. In step 304, it is determined whether or not the end switch has been operated. If not, the process proceeds to step 280 and the above steps are repeated. When the end switch is operated, this routine ends, and the routine proceeds to step 162 of the main routine (see FIG. 3).

Next, the interruption control routine will be described with reference to the flow chart of FIG.

When the interruption switch is operated at step 220 in A mode (see FIG. 4), step 272 in B mode or step 300 (see FIG. 5), step 350 first substitutes Q _B for Q _S and then step 354. To close the nozzle 44. As a result, the discharge of the paint is temporarily stopped, and the process proceeds to step 362.

In step 362, it is determined whether or not the restart switch is operated by operating the key of the keyboard 40. If the determination is negative, the process proceeds to step 350 and the above steps are repeated. As a result, the pressure in the paint tank 14 can be maintained at the pressure before the interruption. When a positive determination is made in step 362, the process proceeds to step 364, the nozzle 44 is opened again, and the process returns to the step next to the step that has been respectively shifted.

As described above, in this embodiment, the discharge flow rate control of the paint is
In the A mode control, the pressure in the paint tank 14 is controlled according to the actual flow rate, so the needle valve
The discharge flow rate can be controlled more accurately than the discharge flow rate control by 46. In addition, since it is possible to cope with a change in flow rate due to temperature change or paint accumulation, it is possible to perform stable coating work without causing unevenness in the film thickness of the paint attached to the object to be coated. .

Further, in the case of the B mode control, a rough control is performed by adjusting the opening of the needle valve 46, and the pressure control is switched to a state in which the paint discharge flow rate is stable to some extent. Working time can be shortened. Also, when the discharge flow rate decreases due to temperature change or paint accumulation, etc., the pressure will be gradually increased accordingly.However, when the pressure becomes equal to or higher than a predetermined value, the opening degree of the needle valve 46 is set again. Since the control can be switched to the adjustment control, the pressure in the paint tank 14 does not rise excessively, and the safety is high.

Further, the spray gun discharge control device 10 according to the present embodiment.
Then, when the painting work is temporarily interrupted, the pressure in the paint tank 14 before the interruption can be maintained, so that when the painting work is restarted, the paint is immediately sprayed at the same discharge flow rate as before the interruption. Therefore, the workability is improved.

In the present embodiment, the map shown in FIG. 7 and FIG. 8 is stored in the memory of the controller 28, and the nozzle opening and the tank pressure are automatically set according to the flow rate.
40, the operator may manually set the value. Further, in this embodiment, the needle valve adjusting shaft 74 is moved by the pulse motor 82, but the needle valve adjusting shaft 74 is visually observed by the operator.
It is also possible to read the rotation of No. 1 and judge it, and rotate the needle valve adjusting shaft a predetermined amount.

〔The invention's effect〕

As described above, the spray gun discharge amount control device according to the present invention has an excellent effect that a stable discharge amount can be automatically maintained at all times without the need for operator monitoring.

In addition to the above effects, there is an effect that a stable discharge amount can be obtained before and after the interruption of the coating work.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a spray gun discharge control device according to the present embodiment, FIG. 2 is a sectional view showing an internal structure of the spray gun, and FIG. 3 is a flow chart showing a main routine of discharge control of paint. 4 is a flow chart showing an A mode control routine, FIG. 5 is a flow chart showing a B mode control routine, FIG. 6 is a flow chart showing a coating interruption control routine, FIG. 7 is a flow rate-nozzle opening characteristic diagram, 8th
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, 28 …… Control device, 32 …… Pressure detector,
36 …… Flow rate detector, 44 …… Nozzle, 46 …… Needle valve.

Continuation of the front page (56) Reference JP-A-63-116764 (JP, A) JP-A-63-111965 (JP, A) Actually opened 62-99355 (JP, U) Actually opened 59-115458 (JP , U)

Claims (3)

(57) [Claims] 1. A discharge amount of a paint from a spray gun which discharges the paint from a nozzle which is connected to the paint tank through a conduit and which can be opened and closed by a needle valve and which mixes with air in the vicinity of the nozzle to spray the paint. Which is a spray gun discharge amount control device, wherein needle valve drive means for driving the needle valve to change the opening of the nozzle, a pressure controller for controlling the pressure in the paint tank, and a paint flowing in the conduit. Flow rate detector for detecting the flow rate of the, and the nozzle from the nozzle by controlling the needle valve drive means to bring the nozzle to a predetermined opening and also controlling the pressure controller according to the value detected by the flow rate detector. And a control unit for controlling the discharge amount of the spray gun. 2. The pressure controller controls the needle valve drive 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 holding means for holding the pressure in the paint tank at the pressure immediately before being closed when the nozzle is closed by a needle valve. Spray gun discharge control device.