JPS6354970A - Control device for paint discharge quantity - Google Patents

Abstract

PURPOSE:To facilitate control of paint discharge quantity by preliminarily setting the number of pulses to be corrected without making data correction for all of the paint flow pulses and making data correction for the set paint flow pulses. CONSTITUTION:The paint flow rates at the respective paint flow pulses are measured by a mass flow meter 4 in the case of generating the plural paint flow pulses per one time of painting cycle and executing painting of works in accordance with said pulses. The measured data are compared with a refer ence value in a microcomputer 2 and the discharge quantity of paint from an automatic painter is corrected and controlled in accordance with the compari son. The correction of the paint flow rate is made by preliminarily setting the number of the pulses to be corrected for the above-mentioned plural paint flow pulses and the corrected data value at the final pulse among the pulses to be corrected is used as the initial value of the next painting cycle. As a result, the control of the paint discharge quantity is facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a paint discharge amount control device for controlling the amount of paint discharged from an automatic coating machine when an object to be coated is coated by an automatic coating machine.

(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 has been proposed, for example, as disclosed in Japanese Unexamined Patent Publication No. 56-139162. In this device, a flow rate needle is installed in the paint supply passage for supplying paint from the paint supply source to the nozzle of the paint sprayer, and a quantity 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 flowmeter, thereby making the amount of paint discharged from the nozzle constant.

By the way, in general, in the painting line for automobile bodies,
The top and side surfaces of the car body are spray-painted using an automatic painting machine. Painting is performed by moving the paint discharging nozzle back and forth in a direction transverse to (perpendicular to) the direction in which the vehicle body is moving on a carrier. Therefore, the movement of the paint discharge nozzle relative to the vehicle body is 2 to 3 as shown in Figure 9.
It becomes a vibration waveform with a period of seconds. At both ends of the lateral movement range of the nozzle, the paint discharge is stopped to prevent double blowing and waste blowing, and a paint can DI area as shown by hatching is formed. Therefore, since the flow of paint forms a pulse train consisting of multiple step pulses that rise and fall rapidly, it is difficult to precisely control the amount of paint discharged using the device disclosed in the above publication. Met.

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. Because of this, there was also the 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 performing painting by generating a plurality of paint flow pulses per one painting cycle by an automatic painting machine, like the above-mentioned spray painting of an automobile body. Another object of the present invention is to provide a paint discharge amount control device that can uniformize the coating film in a coating line where objects to be coated with different paint colors flow together.

(Structure of the Invention) A 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 reference data, and controls the amount of paint discharged from the automatic coating machine. This is a device for correcting and controlling the number of pulses to be corrected for the plurality of paint flow pulses, and corrects the amount of 2 it of paint by setting the number of pulses to be corrected in advance, and also corrects the correction data value at the last pulse among the pulses to be corrected. It is characterized in that it is used as an initial value for the next painting 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.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the drawings, but prior to that explanation, a brief explanation will be given of a spray painting method for an automobile body using an automatic painting machine, which is the premise of the present invention. do.

Figure 11 is a diagram showing a method of spray painting an automobile body using an automatic painting machine.
This is done separately for the top and side. In this figure, the paint discharge status is indicated by symbols ■, ■, ■.
O is a paint OFF area corresponding to the position of the window on the vehicle body, and ■ and ■ are paint ON areas. The area indicated by hunting is the paint cut HJr 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 tttp, in which the vertical axis represents the amount of paint discharged and the horizontal axis represents time. When painting the upper surface of the car body, 12 paint flow pulses
Furthermore, when painting the side surface of a car body, one painting cycle (approximately 60 seconds) is formed by 17 paint flow pulses. In the case of this embodiment, the pulse width τ1 of each paint flow pulse when painting the upper surface of the vehicle body is set to 2.
The pulse period τ is set to 71 seconds, the pulse period τ is set to 4.05 seconds, and the pulse width τ3 of each paint flow pulse when painting the side of the car body is set to 2.14 seconds, and the pulse period τ4 is set to 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 1 is an arithmetic processing unit in the main body of an automatic coating machine, and 2 is 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 hail signal and outputs it to the microcomputer 2. Upstream of the mass flow meter 4, there is an air operation regulator 9 that controls the flow rate of paint.
(hereinafter abbreviated as an air operation regulator) is provided, and this air operation regulator 9 is operated by an air signal from an electric/air conversion device 10 that converts an output signal from the microcomputer 2 into an air signal.

The 1ft/air conversion device 10 has a configuration as shown in FIG. It consists of an electric/pneumatic converter 12 that outputs an air signal proportional to an 8-bit parallel digital signal input from the microcomputer 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 operation 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 includes color change valves 14 for each paint color.
．． ~14N, these color change valves 14A
14.4 are connected to paint supply pipes 16A to 16N via corresponding regulators 154 to 15N of regulator group 15, respectively. The color change valve group 14 also includes a valve 14° connected to the cleaning thinner supply pipe 17 via a regulator 15°,
Regulator 15. A valve 14p connected to the air supply pipe 18 via the air supply pipe 18 is provided. Furthermore, a paint ON/OFF valve 20 is interposed in the paint supply passage 21 between the paint discharge nozzle 3 and the mass flow meter 4.

In the above configuration, the signal outputting the paint color and the amount of paint discharged from the arithmetic processing a1 of the automatic coating machine main body is sent to the microcomputer 2 along with the signal outputting the paint density.
be taken into account. At the same time, the automatic painting machine's main processing unit 1 opens the color change valve for the set paint color (
For example, use this color change valve as 14. ). Here, the microcomputer 2 operates the air operation regulator 9 via the electric/pneumatic converter 10, so that paint begins to flow into the paint supply passage 21. The paint is supplied from the selected paint supply pipe 167 to the regulator 15 and the color change valve 14. The paint is sent to the paint supply passage 21 through the air operator regulator 9 and the mass flow meter 4, and is discharged from the paint discharge nozzle 3 toward the object to be coated. The mass flow meter 4 detects the mass flow rate under certain setting conditions as will be described later, and feeds it back to the microcomputer 2. In this way, the microcomputer 2, the electric/pneumatic converter 101, the air regulator 9, and the mass flow meter 4
By forming a loop, the deviation in the amount of paint discharged is corrected.

By the way, when the mass flowmeter 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 flowmeter becomes a problem. Fourth
The figure shows the response of the mass flow meter 4 to the flow of paint, where the vertical axis is E/Eo and the horizontal axis is time. E is the output of mass flowmeter 4, and Eo is the quality converged to the step input! ! This is the output of the flow meter 4. Referring to Figure 4,
It can be seen that this 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, flow rate correction is performed for all paint flow pulses in FIG. 12 based on this output signal, but FIG. 5 will be explained later together with 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.

At the same time as the car body is carried into a predetermined position, setting signals for the paint color and paint discharge amount are output from the automatic painting machine's main 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, the density according to the paint color.

This density is multiplied by the discharge IQ (volume flow rate), converted into a mass flow rate, and held. Let this mass flow rate be Q (Q, -DS·Q,').

(2) From the electricity/air conversion value storage table, the electricity of the previous painting cycle corresponding to the paint color and discharge amount.

The electric/air conversion value K is outputted as an initial value to the electric/air conversion device 10, and the flow of paint is started. This electric/air conversion value is a positive integer between 0≦ and ≦255 (
decimal number).

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

The MLjILJX (see FIG. 5 and FIG. 6B) microcomputer 2 receives the discharge ON signal for the first paint flow pulse from the automatic coating machine main processing unit 1 at time L1 in FIG. The correction is not disclosed, and the number of times the ejection ON signal occurs is a preset number N.
, the correction starts from the paint flow pulse at time t2 when , , is reached.

The following explanation is based on the output signals shown in the upper part of FIG. 5, that is, the mass when painting the upper surface of the vehicle body,
The target is a total of 4 output signals. In Figure 5, N straight-
It is 2.

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

(2) Assuming that the count number N1 is 2, when a discharge ON signal is received at time t2, the preset time τ starts from that time [2] in order to wait for the discharge amount to stabilize.

The process waits until time t3 when seconds have elapsed.

(3) Sampling frequency f from time t3 to time t4
Hz and the sampling number S is used to sample the output signal of the mass flowmeter 4.

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

(5) This average mass flow rate ζ1. is compared with the mass flow rate set in the initial process to calculate Y=σ, , /Q.

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

(7) When the value of Y is within the allowable range, the electric-air conversion value K is held as is; when it is outside the allowable range, the electric/air conversion value K is held as it is;
Add correction to the empty conversion value K.

If the electric/pneumatic conversion value correction addition amount is Δ and the correction value is T, when Y>1, T= is set to -Δ, and when Y<1, T- is set to +Δ.

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

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

01 Rewrite the value of K in the electric/air conversion value table.

αυ Even if the discharge FF signal is received at time t5, the above-described process is continued for the next output signal pulse as long as the automatic coating device RUN signal is ON.

(Transition) Evaluate the count number of the discharge ON signal from the automatic coating machine main body arithmetic processing unit 1. When this count exceeds a preset number N, (N, -7 in FIG. 5), the correction process ends. In other words, in Figure 5, the seventh
At each time point t6 to t9 of the second output signal, the same processing as that performed at time points t2 to t5 is performed based on the second output signal.

a3 Rewrite the electric/air conversion value storage table each time with the corrected electric/air conversion values for the second to seventh paint flow pulses.

Data stagnation, stoppage (see Figures 5 and 6C) When the count number of the ejection ON signal exceeds 7, the following process is performed.

+11 The corrected electric/air conversion value obtained based on the seventh output signal pulse is stored 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) Painting 4i1RUN signal is OFF at time tlO
When it detects that it has become F, it outputs -255 to the electric/pneumatic converter 10 and fully opens the air operation regulator 9.0 If the paint color of the next workpiece is different from this time, the paint supply passage 21 It is necessary to drain the remaining paint inside and clean the inside of the paint supply passage 21 using cleaning thinner. Therefore, in order to reduce the flow resistance in the passage 21, the air operated regulator 9 is fully opened.

(4) When receiving a signal indicating the end of the cleaning process from the automatic coating machine main body arithmetic processing unit 1, it outputs =O as the TL/air conversion value to the electric/pneumatic converter 10, and fully closes the air operation regulator 9. If the paint color of the next workpiece is the same as this time, the cleaning process is omitted, but in order to close the air operation regulator 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. 7, it is determined whether or not a correction one cycle start signal has been received, and if the start signal is received, the vehicle type i, paint color j, and discharge amount setting number k are read in steps S2 to S4. In step S5 of the 0th order, -0 is output to the 1t/air conversion device 10 to fully open the air operation regulator. Then, in steps S6 and S7, the number of correction start steps N, (11) and the number of correction end steps N, (11 are set to 0, respectively. Then, in step S8
In step S9, the density Ds (Jl is read out) of the paint corresponding to the paint color from the density table in the microcomputer 2, and in step S9, the discharge M (volume flow rate ) QV(i, j
. 0 Next, in step Sll, the volumetric flow rate Qv (n= j + k
) is multiplied by (J) to convert into mass flow rate QII. Further, in step 312, a step count variable is initialized (n-1).

Then, in step 513, -Ks (i, J, k) is output to the electric/pneumatic converter 10, and the above-mentioned initial process is ended.

Next, moving to FIG. 8, n is evaluated in step 514, and when n<N, (1), the next step S15 is performed.
increments n and repeats the evaluation in step 314. When n=N;f+1, the process proceeds to the next step 318, and it is determined whether or not a paint discharge ON signal has been received. When the ejection ON signal is received (time t2 in FIG. 5), τ is determined in the next step S19. Wait for seconds. And τ. After 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 sampling result is Average mass flow rate or average discharge precious stones1. Calculate. In the next step S22, Y=Q, s/Q for evaluation of sampling data.

is calculated, and in the next step S23 it is determined whether this Y is within an allowable range. If the value of Y is outside the allowable range, the process proceeds to step S24 and the electric/pneumatic conversion value is corrected; however, if the value of Y is within the allowable range, the process proceeds to step S31 without making any correction and increments n. do. In step 324, it is determined whether Y is larger than 1 or smaller than 1, and when Y>1, the electric/pneumatic conversion value is corrected by subtracting the corrected bone ΔK from the value of K in step S25 (T= ΔK). Moreover, when Y<1, step 32
In Step 6, the electric/pneumatic conversion value is corrected by adding the corrected bone ΔK to the value of K (+ΔK to T-). The first step S27 is a step to evaluate whether or not the correction is possible, and 0<T<2'55. If so, set T=K (correctable) in step 328, and set T≦ or Ta2
05, in step 329 =K (correction impossible)
shall be.

Then, in step S30, K is output to the electric/air converter 10. In step S31, n is incremented, and in step S32, n is evaluated, and n<N, (1)
When n≧N, (11), the process returns to step 518 and repeats the process described above, and when n≧N (11), the process advances to the next step S33 to rewrite the electric/air conversion value table and store the final corrected electric/air conversion value. For each paint flow pulse where n≧N, +11, the electric current /
IJi is performed using the empty conversion value table, no data correction is performed, and when the cleaning process signal is received in step S34, -255 is output to the electric/pneumatic converter 10 in step S335, and the air operation regulator is fully opened. , return to step S1.

The above is the flow of processing executed by the microcomputer 2. As is clear from the above description, in this embodiment, a predetermined pulse out of a large number of paint flow pulses is selected as a correction target pulse. Since the flow rate is corrected, the coating film can be made 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 the drawing]

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 graph showing the output response characteristics to step human power; Figure 5 is a waveform diagram of the output signal of the mass flow meter during operation of the automatic coating machine;
Figures A, B, and C are explanatory diagrams showing the contents of the processing executed by the microcomputer and the flow of each signal, Figures 7 and 8 are flowcharts of the processing, and Figure 9 is the movement of the paint discharge nozzle of the automatic coating machine. FIG. 1O and FIG. 1L are diagrams illustrating a spray painting method for an automobile body, and FIG. 12 is a diagram illustrating the flow state of paint when painting the top and side surfaces of an automobile body. 1.--Automatic coating machine main unit arithmetic processing unit 2-..Microcomputer 3-.-Paint discharge nozzle 4.--Mass flow meter 9.
...Air operation regulator 10...-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 2 〇-Paint ON/OFF valve

Claims (1)

[Scope of Claims] In an automatic coating machine, when a plurality of paint flow pulses are generated per one painting cycle and an object to be coated is coated using them, the paint flow rate in each of the paint flow pulses is measured. , a paint discharge amount control device that 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, and for the plurality of paint flow pulses, the correction target is The paint discharge amount is characterized in that the number of pulses is set in advance to correct the paint flow rate, and the correction data value of the last pulse among the pulses to be corrected is used as an initial value for the next painting cycle. Control device.