JPH0231849A - Controller for paint discharge from coating device - Google Patents

Abstract

PURPOSE:To facilitate adjustment and to improve cleanability by providing a flow sensor for detecting the paint discharge in a non-contact state, and inputting a feedback signal to a control circuit on the downstream side of the color-change valve provided to a paint passage connecting a coating gun and plural paint supply sources. CONSTITUTION:A color-change signal is received, an A-color paint is selected by the color-change valve 3, and an optimum set discharge amt. corresponding to the characteristic, etc., of the A-color paint is outputted by a controller 21 to an electropneumatic transducer 12 as a discharge control signal VQ which is transduced into an air pressure. As a result, an air operating signal Pa is inputted to a paint regulator 9, hence the opening degree conforming to the discharge amt. of the A-color paint is maintained, and the paint is supplied to the coating gun 4. The flow rate of the paint in the paint passage 15 is detected by a non-contact flow sensor 16 and always fed back to the controller 21, and the discharge amt. is held at a set value. Accordingly, the discharge amt. is quite unaffected by the fluctuations in the paint conditions due to the changes in the temp., paint, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a paint discharge amount control device for an automatic painting apparatus for painting, for example, an automobile body.

2. Description of the Related Art As this type of paint discharge amount control device, one using a gear pump as shown in FIG. 3 is widely known. In the figure, la, lb, lc...In are paint supply sources for each color, and 2a, 2b, 2c...2n are paint supply sources 1a to 2n.
A positive displacement gear pump is provided for the same number as In, 3 is a color change valve, and 4 is a paint gun.As is well known, by switching the color change valve 3 in response to a color change signal, multiple paint supply sources can be used. One of the paints 1a-1n is selected and supplied to the paint gun 4 side. At this time, the amount of paint discharged is adjusted by controlling the rotational speed of the gear pumps 2a to 2n, which are rotationally driven by the motor 5, according to the coating conditions and the like.

6 is a cock valve, 7 is a regulator, and 8 is an on-off valve.

Also, instead of the gear pump system described above, there is also one that uses an air-operated paint regulator as shown in FIG. In this system, an air-operated paint regulator 9 replacing the gear pumps 2a to 2n described above and a temperature sensor 10 are provided between a color change valve 3 and a paint gun 4, and a discharge voltage is output as an electric signal from a controller 11. The amount control signal is converted into a pneumatic signal by an electro-pneumatic converter 12 and then applied to the paint regulator 9, thereby controlling the opening degree of the paint regulator 9 and adjusting the discharge amount.

In this case, by feeding back the output of the temperature sensor 10 to the controller 11, the actual discharge amount is corrected and controlled based on the correlation between temperature and viscosity. 14 is an air pressure source.

Problem to be Solved by the Invention However, in the former paint discharge amount control device using gear pumps 2a to 2n, gear pumps 2a to 2n for the number of colors to be painted must be installed upstream of the color change valve 3. , the initial cost at the time of equipment installation is high, and it is disadvantageous in terms of installation space and maintainability. Also, it is possible to reduce the number of pumps by installing a gear pump downstream of the color change valve 3, but in that case, one pump will be used for multiple paint colors. Become. Therefore, when changing colors, the gear pump, which has extremely poor cleaning properties, must be cleaned each time using cleaning thinner and air, which is undesirable because excess cleaning thinner and air are consumed. Furthermore, the use of a large amount of cleaning thinner and air during cleaning causes wear of the teeth of the gear pump, and there is a concern that the pump's metering accuracy may deteriorate.

On the other hand, in the latter type of paint discharge amount control device using an air-operated paint regulator 9, paint conditions including the relationship between the temperature and viscosity of the paint to be discharged, and installation conditions of the paint machine (hose length, hose diameter, etc.) ) etc., it is necessary to collect discharge amount data for each paint and each sprayer and input it to the controller 11 in advance, which requires a great deal of time for so-called adjustment work before actual operation.

Moreover, if the paint color is changed or equipment is replaced, the same adjustment work as above must be performed each time the paint conditions or installation conditions change, resulting in redundant non-operating time. Become.

The present invention has been made in view of the various problems mentioned above, and its purpose is particularly to facilitate adjustment work;
Moreover, it is an object of the present invention to provide a paint discharge amount control device with excellent cleaning properties.

Means for Solving the Problems The paint discharge amount control device of the present invention is provided in a paint passage connecting a paint gun and a plurality of paint supply sources, and is configured to supply paint to be supplied to the paint gun in response to a color change signal. a color change valve that selectively switches the source; an air-operated paint regulator installed in the passageway that controls the paint discharge amount; and a discharge amount control that outputs a discharge amount control signal of the paint to be discharged as an electrical signal. a circuit section, an electro-pneumatic converter that converts a discharge amount control signal into a pneumatic signal and applies it to the paint regulator, and is provided downstream of the color change valve in the passage and detects the amount of paint discharged without contact. and a flow rate sensor that provides a discharge amount feedback signal to the control circuit section.

Function: According to this structure, the actual paint discharge amount (flow rate) is constantly fed back, and the opening degree of the paint regulator is controlled so as to achieve the optimum discharge amount. By understanding and managing the actual discharge amount, even if the viscosity of the paint changes due to temperature changes, for example, the total paint discharge amount will not be affected.

Embodiment FIG. 1 is a diagram showing an embodiment of the present invention, and parts common to FIG. 4 are given the same reference numerals.

The color change valve 3 can be understood as a plurality of switching valves arranged in parallel, and includes a plurality of paint inflow ports 23a to 23n for one discharge port 13. The discharge port 13 side is connected to the paint gun 4 via the paint passage 15, while a plurality of paint inflow boats 23
a to 23n are independent for each paint color, for example, A color, B color...N colors, and these paint inflow ports 2
3a to 23n are individually connected to the paint supply sources 1a to 1n of the corresponding colors via paint passages 17. The color change valve 3 is for selectively switching paint colors A to N, and selectively opens one of the plurality of switching valves based on a color change signal. This allows paint of the corresponding color to be supplied to the painting gun 4 side.

The paint passage 15 that connects the color change valve 3 and the painting gun 4 is equipped with an air-operated paint regulator and a non-contact flow rate that non-contact detects the flow rate (discharge amount) of the paint flowing inside the paint passage 15. A sensor 16 (eg, an oval micromotion flowmeter) is provided. Therefore, the flow rate of the paint flowing through the paint passage 15 is detected by the flow rate sensor 16, and the controller 2 (described later)
1 is fed back.

The opening degree of the paint regulator 9 is controlled in response to an air pressure signal, that is, an air operation signal Pa, from an electro-pneumatic converter 12. The electro-pneumatic converter 12 functions as a so-called electro-pneumatic proportional valve that receives the discharge amount control signal VQ output as an electric signal from the controller 21 and outputs a pneumatic pressure signal proportional to the input current. Via this electro-pneumatic converter 12, the paint regulator 9 receives the discharge amount control signal ■ output from the controller 21.
. The opening degree will be adjusted accordingly.

The controller 21 as a discharge amount control circuit section is configured mainly of a microcomputer, for example, and the optimum discharge amount for each paint is preset in this controller 21. After receiving the color change signal, the electro-pneumatic converter 1 outputs the discharge amount of the corresponding paint as a discharge amount control signal VQ.
2, while receiving the flow rate feedback signal VF from the flow ffi sensor 16 and controlling so that the deviation between the set discharge amount and the actual discharge amount becomes zero.

According to this embodiment, for example, when paint of color A is selected by the color change valve 3 in response to a color change signal, the controller 21 discharges the optimal set discharge amount according to the characteristics of the paint of color A. Electropneumatic converter 1 as quantity control signal VQ
2, and the electro-pneumatic converter 12 converts the electrical signal into a corresponding pneumatic pressure. As a result, paint regulator 9
receives the air operation signal Pa and is maintained at an opening suitable for the discharge amount of A color paint, and the paint is supplied to the paint regulator 9.
The flow rate is controlled by and supplied to the coating gun 4 side.

The flow rate of the paint flowing through the paint passage 15 is detected by the flow rate sensor 16 and is constantly fed back to the controller 21 side, so that feedback control is performed so that the actual paint discharge amount matches the set discharge amount.

Here, even if the viscosity of the paint changes due to the external environmental temperature while the paint is being discharged, the actual paint discharge amount is detected and feedback controlled as described above, so the paint discharge amount will fluctuate due to the change in viscosity. There's nothing to do.

FIG. 2 shows the correlation between the paint flow rate, temperature, and air operation signal (pressure) when the paint flow rate is feedback-controlled as described above and when it is not. As is clear from the figure, when feedback control is not performed, the amount of paint discharged changes as the paint temperature increases even if the air operating pressure is kept constant. On the other hand, when the discharge rate is controlled by feed rate, the air operating pressure changes in accordance with changes in paint temperature (paint viscosity), and the discharge rate is kept approximately constant.

Effects of the Invention As described above, according to the present invention, since the actual paint discharge amount is directly detected using a non-contact flow rate sensor and feedback control is performed, paint conditions due to temperature changes, paint changes, etc. It is now possible to control the amount of paint discharged without being affected by fluctuations in equipment conditions, as well as changes in equipment conditions due to equipment modification or maintenance, making it possible to control the amount of paint discharged more precisely than before. At the same time, the precision of quantitative dispensing is significantly improved, and troublesome adjustment work is no longer necessary.

Furthermore, since the flow rate sensor does not come into contact with the paint, it is possible to perform the same cleaning as without the sensor even during color change cleaning, which reduces waste of cleaning thinner and paint, which is advantageous in terms of space and maintenance. Sexuality also improves.

[Brief explanation of the drawing]

Fig. 1 is a configuration explanatory diagram showing one embodiment of the present invention, Fig. 2 is a characteristic diagram showing the correlation between paint flow rate, temperature, and air operating pressure, and Figs. 3 and 4 are conventional paint discharge rate control. FIG. 2 is an explanatory diagram of the configuration of the device. 1a to 1n... Paint supply source, 3... Color change valve, 4... Paint can, 9... Air operated paint regulator, 12... Electro-pneumatic converter, 151
7...Paint passage, 16...Flow rate sensor, 21...
Controller as a discharge amount control circuit section.

Claims (1)

[Claims] (1) A color change valve installed in a paint passage connecting a paint gun and a plurality of paint supply sources to selectively switch the supply source of paint to be supplied to the paint gun in response to a color change signal, and a color change valve installed in the passage. an air-operated paint regulator that controls the amount of paint discharged, a discharge amount control circuit that outputs a control signal for the amount of paint to be ejected as an electrical signal, and an air-operated paint regulator that converts the amount control signal of the paint to be ejected into an air pressure signal. an electro-pneumatic converter provided to the paint regulator; and a flow rate sensor provided downstream of the color change valve in the passageway to detect the amount of paint discharged in a non-contact manner and provide a discharge amount feedback signal to the control circuit section. A paint discharge amount control device for a coating device, comprising: