JPH043266B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a paint discharge amount control device for controlling the amount of paint discharged from an automatic coating machine when painting an object to be coated with an automatic coating machine. Regarding.

(Prior art) Conventionally, when spray painting car bodies at automobile manufacturing plants, the viscosity of the paint film changes with changes in the external environment, resulting in fluctuations in the amount of paint discharged from the nozzle, resulting in uneven paint films. There was a problem.

Therefore, a paint discharge amount control device as disclosed in, for example, Japanese Patent Application Laid-open No. 139162/1983 has been proposed. In this device, a flow meter is installed in the paint supply passage for supplying paint from the paint supply source to the nozzle of the paint sprayer, and a flow control device is installed in the paint supply passage between the paint supply source and the flow meter. This flow rate control device is controlled by a microcomputer based on the paint flow rate detected by the flow meter, and the amount of paint discharged from the nozzle is made constant.

By the way, in general, in a car body painting line, spraying equipment is applied separately to the top and side surfaces of the car body using an automatic paint machine, but in this case, as shown in Fig. In order to ensure the width b, painting is performed while the paint discharge nozzle is reciprocated in a direction transverse to (perpendicular to) the direction of movement of the vehicle body being moved on a carrier, as shown in FIG. Therefore, the movement of the paint discharge nozzle relative to the vehicle body has a vibration waveform with a period of 2 to 3 seconds as shown in FIG. At both ends of the nozzle's lateral movement range, steps are taken to prevent double blowing and waste blowing.
The discharge of paint is stopped, and a paint cut area as shown by hatching is formed. Therefore, since the flow of paint forms a pulse train consisting of a plurality of step-shaped pulses that rise rapidly and then fall rapidly, the device disclosed in the above publication does not allow for accurate control of the amount of paint discharged. Control was difficult.

In addition, in the painting line for automobile bodies, bodies with different paint colors are mixed, and the bodies with the same painting conditions such as paint color and paint output amount are not necessarily brought in continuously, but intermittently. As a result, there was a problem that variations in the coating film were likely to occur between coating cycles under the same conditions.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention provides a method for spray painting of automobile bodies by using an automatic painting machine.
A paint discharge amount control device that can achieve a uniform coating film in a painting line where multiple paint flow pulses are generated per painting cycle and objects to be painted with different colors flow mixedly. The purpose is to provide.

(Structure of the Invention) The paint discharge amount control device according to the present invention measures the paint flow rate at each paint flow pulse in an automatic coating machine, compares this measurement data with basic data, and controls the amount of paint discharged from the automatic coating machine. A device that corrects and controls a certain number of pulses of the plurality of paint flow pulses in advance as correction target pulses, corrects the paint flow rate with respect to the correction target pulses, and performs correction control of the paint flow rate. The present invention is characterized in that the correction data value for the final pulse of the target pulses is used as the initial value for the next coating cycle.

(Effects of the Invention) According to the present invention, since the paint flow pulse is corrected, precise control of the discharge amount is possible, and uniformity of the coating film can be achieved. Furthermore, rather than performing data correction for all paint flow pulses, the number of pulses to be corrected is set in advance and data correction is performed for the set paint flow pulses, which makes control easier. In addition, the correction data value of the final paint flow pulse among the above correction target pulses, that is, the correction data value when the flow condition is sufficiently stable, is used as the initial value for the next painting cycle under the same conditions (painting color and discharge amount). Since this method is used, it is possible to substantially eliminate variations in the discharge amount between coating cycles.

(Example) An example of the present invention will be described below in detail with reference to the drawings, but before that description, a brief description will be given of a method of spray painting an automobile body using an automatic painting machine, which is the premise of the present invention. .

FIG. 11 is a diagram showing a method of spray painting an automobile body using an automatic painting machine, and this spray painting is performed separately on the top and side surfaces of the vehicle body. In this figure, the paint discharge status is indicated by symbols.
, where is the paint OFF area corresponding to the position of the window on the vehicle body, and is the paint ON area. The hatched area is the paint cut area.

FIG. 12 is a diagram showing the flow state of paint when spray painting is performed on the top and side surfaces of the vehicle body shown in FIG. 11, in which the vertical axis represents the amount of paint discharged and the horizontal axis represents time. One painting cycle (approximately 60 seconds) is formed by 12 paint flow pulses when painting the top side of the car body and 17 paint flow pulses when painting the sides of the car body. It shows that it will be done. In the case of this example, the pulse width γ ₁ of each paint flow pulse when painting the upper surface of the car body is 2.71 seconds,
The pulse period γ ₂ is 4.05 seconds, and the pulse width γ ₃ of each paint flow pulse when painting the side of the car body is 2.14.
seconds, and the pulse period γ ₂ is selected to be 3.64 seconds.

FIG. 1 is a schematic diagram showing the configuration of a paint discharge amount control device according to the present invention, in which numeral 1 represents an arithmetic processing unit in the main body of an automatic coating machine, and numeral 2 represents a microcomputer. 3 is a paint discharge nozzle provided at the downstream end of the paint supply passage 21, and 4 is a mass flow meter interposed in the middle of the passage 21. As shown in FIG. 2, this mass flowmeter consists of a sensor section 5, an electronics box section 6, a mass flow rate digital monitor 7, and a temperature/density digital monitor 8. The electronics box section 6 processes the representing signal and outputs it to the microcomputer 2. An air operation regulator 9 (hereinafter abbreviated as air operator) is provided upstream of the mass flow meter 4 to control the flow rate of the paint. 2 converts the output signal into an air signal.
It is activated by the pneumatic signal from the pneumatic converter 10. The electric/pneumatic converter 10 has a configuration as shown in FIG. 3, and includes a fixed pressure reducing valve 11 that reduces the air pressure supplied from an air supply source, and
An electric/pneumatic converter 1 outputs an air signal proportional to an 8-bit parallel digital signal input from a microcomputer 2 using the air pressure reduced by the microcomputer 2.
2 and a variable ratio relay 13. The variable ratio relay 13 amplifies the air signal output from the electric/pneumatic converter 12, and operates the air operator regulator using the amplified air pressure.

On the other hand, a color change valve group 14 is arranged at the upstream end of the paint supply passage 21. This color change valve group 14 has color change valves 14 _A to 14 _N for each paint color, and these color change valves 14 _A to 14 _N are connected to corresponding regulators 15 A to 14 _N of the regulator group 15, respectively.
15 _N respectively via paint supply pipes 16 _A to 16
Connected to _N. Further, the color change valve group 14 includes a valve 14 _O connected to the cleaning thinner supply pipe 17 via a regulator 15 _O ;
A valve _14P connected to the air supply pipe 18 via a regulator _15P is provided. Further, in the paint supply passage 21, a paint ON/OFF valve 20 is provided between the paint discharge nozzle 3 and the mass flow meter 4.
is interposed.

In the above configuration, signals representing the paint color and paint discharge amount outputted from the automatic coating machine main body arithmetic processing unit 1 are taken into the microcomputer 2 together with a signal representing the paint density. At the same time, the automatic painting machine main processing unit 1 opens the color change valve of the set paint color (for example, this color change valve is 14 _J ). Here, the microcomputer 2 operates the air operator 9 via the electric/pneumatic converter 10, so that paint begins to flow into the paint supply passage 21. The paint is applied to the regulator 1 from the selected paint supply pipe 16 _J.
5 _J and the color change valve 14 _J , the paint is sent to the paint supply passage 21, passes through the air operator 9 and the mass flow meter 4, and is discharged from the paint discharge nozzle 3 toward the object to be painted. The mass flowmeter 4 detects the mass flow rate under certain set conditions as will be described later, and provides feedback to the microcomputer 2. In this way, the microcomputer 2,
The electric/pneumatic converter 10, the air operator 9, and the mass flow meter 4 form a loop to correct deviations in the amount of paint discharged.

By the way, when the mass flow meter 4 detects a paint flow pulse that suddenly rises in a step-like manner as shown in FIG. 12 described above, the responsiveness of the mass flow meter becomes a problem. FIG. 4 is a diagram showing the response of the mass flowmeter 4 to the flow of paint, and the vertical axis is E/E _p ,
The horizontal axis is time. E is the output of mass flowmeter 4, E _p
is the output of the mass flowmeter 4 converged with respect to the step input. Referring to FIG. 4, it can be seen that the mass flow meter 4 follows the step input with a delay of 0.2 to 0.3 seconds.

FIG. 5 shows output signal pulses of the mass flowmeter corresponding to the paint flow pulses of FIG. 12, which were assumed in consideration of the response of the mass flowmeter described above. In the present invention, based on this output signal, flow rate correction is performed for all the paint flow pulses in FIG. 12, but the explanation of FIG. 5 will be described later together with the explanation of the operation of the microcomputer 2.

The contents of the process executed by the microcomputer 2 are shown in FIGS. 6A to 6C, and can be temporally divided into three processes.

Initial Process (See FIG. 6A) At the same time as the vehicle body is carried into a predetermined position, setting signals for the paint color and paint discharge amount are outputted from the automatic coating machine main body arithmetic processing unit 1 to the microcomputer 2. At the same time, the automatic painting machine main processing unit 1 opens the color change valve _14J of the set paint color. The signal taken into the microcomputer 2 is processed as follows.

(1) From the density table, find the density D _s corresponding to the paint color, multiply this density by the discharge amount Q _v (volume flow rate), convert it into a mass flow rate, and hold it. Let this mass flow rate be Q _n (Q _n = D _s・Q _v ).

(2) Read the electric/pneumatic conversion value K of the previous coating cycle corresponding to the paint color and discharge amount from the electric/pneumatic conversion value storage table, and use this electric/pneumatic conversion value K as the initial value in the electric/pneumatic conversion device. 10 and start the paint flow. This electric/pneumatic conversion value K is a positive integer and has a value of 0≦K≦255 (decimal number).

The purpose of this initial process is to stabilize the output signal of the mass flowmeter 4.

Correction process (see FIGS. 5 and 6B) The microcomputer 2 at time t1 in FIG.
, a discharge ON signal for the first paint flow pulse is received from the automatic coating machine's main processing unit 1, but the correction is not immediately disclosed, and the number of occurrences of the discharge ON signal reaches a preset number N _i The correction is disclosed from the paint flow pulse at time t2.
The following explanation is directed to the output signal shown in the upper part of FIG. 5, that is, the output signal of the mass flow meter 4 when painting the upper surface of the vehicle body. In FIG. 5, N _i =2.

(1) Receive discharge ON signals at time points t1 and t2 from the automatic coating machine main body processing unit 1: Count the number of times.

(2) When the count number N _i =2 and a discharge ON signal is received at time t2, the system waits for the discharge amount to stabilize from time t2 until time t3 when a preset time γ ₀ seconds has elapsed.

(3) The output signal of the mass flowmeter 4 is sampled with a sampling frequency fHz and a sampling number S from time t3 to time t4.

(4) Calculate the average value of the sampled data,
Obtain the average mass flow rate _ns .

(5) Compare this average mass _ns with the mass flow rate set in the initial process and calculate Y = _ns /Q _n .

(6) Determine whether Y is within the allowable range.

(7) When the value of Y is within the allowable range, the electric-to-air conversion value K is held as is; when it is outside the allowable range, the electric-to-air conversion value K is corrected. Electricity/
If the empty conversion value correction addition amount is ΔK and the correction value is T, then when Y>1, T=K−ΔK, and Y
When <1, T=K+ΔK.

(8) Determine the validity of the value of T. If valid, that is, 0<T<255, the value of K is replaced with the value of T. K if T≧0 or T≦255
The value of is not corrected.

(9) Output the value of K to the electric/pneumatic converter 10 to correct the actual amount of paint discharged.

(10) Rewrite the value of K in the electric/air conversion value table.

(11) Even if the discharge OFF signal is received at time t5, the above-mentioned process continues for the next output signal pulse as long as the automatic coating machine RUN signal is ON.

(12) Discharge from automatic coating machine main processing unit 1
Evaluate the ON signal count. When this count exceeds a preset number of times N _e (N _e =7 in FIG. 5), the correction process ends.
That is, in FIG. 5, for each time point t6 to t9 of the seventh output signal, the same processing as that performed for the time point t2 to t5 is performed based on the second output signal.

(13) The electric/air conversion value storage table is rewritten each time with the corrected electric/air conversion values for the second to seventh paint flow pulses.

Correction data storage and correction stop process (see FIG. 5 and FIG. 6C) When the count number of the ejection ON signal exceeds 7, the following process is performed.

(1) Store the corrected electric/air conversion value obtained based on the seventh output signal pulse in the electric/air conversion value storage section.

(2) For the 8th to 12th paint flow pulses, the discharge amount is controlled by the electric/air conversion value setting made for the 7th paint flow pulse, and the electric/air conversion value table is rewritten. do not have.

(3) When it is detected that the paint machine RUN signal has turned OFF at time 10, K=255 is output to the electric/pneumatic conversion value 10, and the air operator regulator 9 is fully opened. If the paint color of the next workpiece is different from the current color, it is necessary to discharge the residual paint in the paint supply passage 21 and clean the inside of the paint supply passage 21 using cleaning thinner. Therefore, passage 2
The air operator 9 is fully opened to reduce the flow resistance within the air conditioner 1.

(4) When receiving the cleaning process completion signal from the automatic coating machine main unit processing unit 1, the electric/pneumatic converter 10 receives the electric/pneumatic converter 10.
Output the empty conversion value K=0 and fully close the air operator 9. If the paint color of the next workpiece is the same as this time, the cleaning step will be omitted, but
In order to close the air operator 9, a false cleaning process end signal is received.

(5) Finish one cycle of painting process and wait for the next work.

FIGS. 7 and 8 are flowcharts illustrating in more detail the processing executed by the microcomputer 2 described above.

First, in step S1 of FIG.
It is determined whether or not a cycle start signal has been received, and if the cycle start signal is received, the vehicle type i,
Read the coating color j and discharge amount setting number k. In the next step S5, K=0 is output to the electric/pneumatic converter 10 to fully close the air operator regulator. Then, in steps S6 and S7, the correction start step number is
N _i (i) and the number of correction end steps N _e (i) are set respectively. Next, in step S8, the density D _s (j) of the paint corresponding to the paint color is read out from the density table in the microcomputer 2 and set.
In addition, in step S9, the discharge amount (volume flow rate) Q _v (i,
j, k). In the next step S10,
The electric/pneumatic conversion device K _s (i, j, k) corresponding to the vehicle type, paint color, and discharge amount setting number is read out from the electric/pneumatic conversion value storage table in the microcomputer 2 and set. Next, in step S11, the volumetric flow rate Q _v
(i, j, k) is multiplied by the density D _s (j) to create a mass flowmeter.
Convert to Q _n . Further, in step S12, a step count variable is initialized (n=1). Then, in step S13, K=K _s is applied to the electric/pneumatic converter 10.
(i, j, k) is output, and the above-mentioned initial process is completed.

Next, moving to FIG. 8, n is evaluated in step S14, and when n<N _i (i), n is incremented in the next step S15 and the evaluation in step S14 is repeated. Then, when n=N _i (i), the process advances to the next step S18 and it is determined whether or not a paint discharge ON signal has been received. Once the discharge ON signal is received (time t2 in Figure 5), proceed to the next step.
Wait for γ ₀ seconds at S19. After τ ₀ seconds have elapsed, in step S20, the discharge amount is sampled based on the output of the mass flowmeter 4 (from time t3 to t4 in Fig. 5, sampling frequency fHz, sampling number S), and in the next step S21. , the average mass flowmeter of this sampling result i.e. the average discharge rate
Calculate _ns . In the next step S22, Y= _ns / _Qn is calculated for evaluation of the sampling data,
In the next step S23, it is determined whether this Y is within the allowable range. If the value of Y is outside the allowable range, the process proceeds to step S24 and the electric/pneumatic converter value K is corrected; however, if the value of Y is within the allowable range, the process proceeds to step S31 without making any corrections. Increment. In step S24, it is determined whether Y is greater than 1 or less than 1. If Y>1, the electric/pneumatic converter value is corrected by subtracting the correction amount ΔK from the value of K in step S25 (T =K-
ΔK). Further, when Y<1, in step S26, a correction amount ΔK is added to the value of K to correct the electric/pneumatic converter value (T=K+ΔK). The next step S27 is a step to evaluate whether correction is possible or not. If 0<T<255, step S28 sets T=K (correction possible), and if T≦ or T≧255, step S29 sets K=K (correction possible). impossible). Then, in step S30, K is output to the electric/pneumatic converter 10. In step S31, n is incremented, and in step S32, n is evaluated. Then, when n<N _e (i), the process returns to step S18 and the above-mentioned process is repeated, and when n≧N _e (i), the process proceeds to the next step S33, where the electric/air conversion value table is rewritten and the final Stores the corrected electric/air conversion value. Each paint flow pulse where n≧N _e (i) is controlled by the electric/pneumatic conversion value table rewritten in step S33, and no data correction is performed. When the cleaning process signal is received in step S34, the electric/pneumatic converter 10 is
Output K=255 to fully open the air operator and return to step S1.

The above is the flow of processing executed by the microcomputer 2. As is clear from the above explanation, in this embodiment, a predetermined pulse out of a large number of paint flow pulses is selected as a pulse to be corrected to determine the flow rate. Since the correction is performed, it is possible to make the coating film uniform. In addition, the correction data value of the final paint flow pulse among the correction target pulses in one painting cycle is used as the initial value for the next painting cycle (the next painting cycle with the same paint color and discharge amount). This has the effect of almost eliminating variations between painting cycles.

[Brief explanation of drawings]

Fig. 1 is a schematic block diagram of the paint discharge rate control device according to the present invention, Fig. 2 is a block diagram of a mass flow meter, Fig. 3 is a block diagram of an electric/pneumatic converter, and Fig. 4 is a block diagram of a mass flow meter. Figure 5 is a waveform diagram of the output signal of the mass flowmeter during operation of the automatic paint coating machine, Figure 6 A, B and C are the details of the processing executed by the microcomputer and An explanatory diagram showing the flow of each signal, Figures 7 and 8 are process flowcharts, Figure 9 is a diagram explaining the movement of the paint discharging nozzle of an automatic painting machine, and Figures 10 and 11 are diagrams of an automobile. FIG. 12 is a diagram illustrating a method of spray painting a vehicle body. FIG. 12 is a diagram illustrating the flow of paint when painting the top and side surfaces of a vehicle body. 1...Automatic painting machine main body calculation processor, 2...Microcomputer, 3...Paint discharge nozzle, 4...
...Mass flow meter, 9...Air operator regulator, 1
0...Electric/pneumatic conversion device, 14...Color change valve group, 15...Regulator group, 16...Paint supply piping group, 17...Thinner supply piping, 18...
...Air supply piping, 20...Paint ON/OFF valve.

Claims (1)

[Scope of Claims] 1. In an automatic coating machine, when a plurality of paint flow pulses are generated per one coating cycle and an object to be coated is coated using them, the paint flow rate in each of the paint flow pulses is measured. The discharge amount control device compares this measurement data with a reference value and corrects and controls the amount of paint discharged from the automatic coating machine based on this comparison, wherein one of the plurality of paint flow pulses A number of pulses are set in advance as correction target pulses, and the paint flow rate is corrected for the correction target pulses, and the correction data value of the last pulse of the correction target pulses is set at the beginning of the next painting cycle. A paint discharge amount control device characterized in that the amount is used as a value.