JPS6354969A - Control device for paint discharge quantity - Google Patents

Abstract

PURPOSE:To permit precise control of discharge quantity and to uniformize coated films by making data correction respectively of all of plural 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 such pulses. The measured data are compared with a reference value in a microcomputer 2 and the paint discharge quantity from an automatic painter is corrected and controlled in accordance with the comparison. The correction of the paint flow rate for all the paint flow pulses is made and the corrected data value of the final paint flow pulses in one time of painting cycle is used as an initial value for the next painting cycle. As a result, the precise control of the discharge quantity is permitted and the coated films are uniformized. The dispersion of the discharge quantity between the painting cycles is substantially eliminated.

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 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 2+ quantity control device is controlled by a microcomputer based on the paint flow rate discharged by the flowmeter, thereby making the paint discharge rate 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 discharge of paint is stopped to prevent double blowing and waste blowing, and paint fill areas as shown by hatching are 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.

(Statement 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, as in the above-mentioned spray painting of automobile bodies. It is an object of the present invention 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 coating colors are mixed.

(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 that corrects and controls the paint flow rate for all paint flow pulses, and uses the correction data value of the final paint flow pulse in one painting cycle as the initial value for the next painting cycle. It is characterized by the following.

(Effects of the Invention) According to the present invention, since data is corrected for each of the plurality of paint flow pulses, precise control of the discharge amount is possible, and a uniform coating film can be achieved. In addition, the corrected data value of the final paint flow pulse in the current painting cycle, that is, the data value when the paint flow state is most stable, is used as the initial value for the next painting cycle under the same conditions (paint color and discharge amount). Therefore, variations in discharge amount between coating cycles can be substantially eliminated.

(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.
It is divided into top) and side.

In this figure, paint discharge states are indicated by symbols ■, ■, and ■, where ■ is a paint OFF area corresponding to the position of the window of the vehicle body, and ■ and ■ are paint ON areas. The area shown by hunting 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. It is assumed that 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. In the case of this example, the pulse width of each paint flow pulse when painting the upper surface of the car body is 1 to 2.7.
1 second, the pulse period τ2 is 4.05 seconds, and the pulse width τ3 of each paint flow pulse when painting the side of the car body is 2.
．． 14 seconds, and the pulse period τ4 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 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 flowmeter interposed in the middle of the passage 21.As shown in FIG. 5. Electronics box unit 6, consisting of xi flow rate digital unitaf and temperature/density digital monitor 8, electronics box unit 6 processes the signal indicating the mass flow rate of paint detected by sensor unit 5 and outputs it to a microcomputer. It is configured to output to 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 electric/pneumatic conversion device 10 has a configuration as shown in FIG. is used, and outputs an air signal proportional to the 8-bit parallel digital signal input from the microcomputer 2.
It consists of an empty converter 12 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.
A~14. These color change valves 14A
~14% are connected to the paint supply pipes 16^~16N through the corresponding regulators 15A-15% of the regulator group 15, respectively. The color change valve group 14 also includes a valve 140 connected to the cleaning thinner supply pipe 17 through a regulator 15°, and a valve 14. connected to the air supply pipe 18 through a regulator 15F. is provided. Further, in the paint supply passage 21, a paint ON/OFF pulp 20 is interposed between the paint discharge nozzle 3 and the mass flow meter 4.

In the above configuration, the signals output from the processing unit 1 of the automatic coating machine main body, which indicate the paint color and the amount of paint discharged, are sent to the microcomputer 2 along with the signal indicating 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 (
This color change valve is, for example, 14J). Here, the microcomputer 2 operates the air operation regulator 9 via the electric/pneumatic converter IO, so that paint starts flowing into the paint supply passage 21. The paint is supplied to the selected paint supply pipe 16. The paint is sent to the paint supply passage 21 via the regulator 15J and the color change valve 14J, passes through the air operation regulator 9 and the mass flow meter 4, and is discharged from the paint discharge nozzle 3 toward the object to be painted. 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 10. Air operation regulator 9 and 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/E a and the horizontal axis is time. E is the output of the mass flowmeter 4, and Eo 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 human power 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 micro combinator 2 are shown in FIGS. 6A and 6B, and can be temporally divided into three processing steps.

Distance...mileage (see FIG. 6A) 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 outputted to the microcomputer 2 from the calculation processing R1 of the automatic coating machine main body. At the same time, the automatic coating machine main processing unit 1 outputs color change pulp 14 of the set paint color. The signal received by the microcomputer 2 is processed as follows.

+1+　Density according to the paint color from the density table.

This density is multiplied by the discharge amount Q (volume flow rate) to convert it into a ¥tI flow rate and hold it. Let this mass flow rate be Q (Q-=DS·Qv').

(2) From the electric/air conversion value storage table, the electric/air conversion value K of the previous coating cycle corresponding to the coating color and discharge amount is successively retrieved, and the t/air conversion value K is used as the initial value to perform t/air conversion. Output to device 10 and start paint flow. This electric/pneumatic conversion value has a positive integer value of 0≦≦255 (decimal number).

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

When the microcomputer 2 receives the discharge ON signal for the first paint flow pulse from the automatic coating machine main processing unit 1,
Flow rate correction processing for this paint flow pulse is started. The following explanation will be based on the output signal shown in the upper part of FIG.
The output signal of f1 flowmeter 4 is targeted.

(1) When a discharge ON signal is received from the processing unit 1 of the automatic coating machine main body at time t1, the process starts at time t1 for a preset period of time in order to wait for the discharge amount to stabilize.

The process waits until time t2 when seconds have elapsed.

(2) The output signal of the mass flowmeter 4 is sampled at the sampling frequency fH2 and the sampling number S from time t2 to time t3.

(3) Calculate the average value of the sampled data,
We obtain an average mass flow rate ζ,1.

(4) This average mass flow Mopen, , is compared with '1 set in the initial process with the wall flow rate, and Y-ζ, , /Q is calculated.

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

(6) 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 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, then when Y>1, T==−Δ, and when Y<1, T=+Δ.

(7) Determine the validity of the value of T. If it is valid, that is, 0<T<255, the value of K is replaced with the value of T. If T2O or T≦255, the value of K is not corrected.

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

+91! /Rewrite the value of K in the empty conversion value table.

αω Even if the discharge OFF signal is received at time t4, as long as the automatic coating machine RUN signal is ON, the above-mentioned processing is performed based on the pulse of the subsequent output signal. Then, from each time point t5 to t8 of the final (12th) output signal pulse, the same processing as that for the first output signal pulse is continued.

OB The electric/air conversion value storage table is rewritten each time with the corrected electric/air conversion value for each feed flow pulse.

When it is detected that the coating station RUN signal is turned OFF at time t9 during correction data storage, the following processing is performed.

+1+ The corrected electric/air conversion value obtained based on the final (12th) output signal pulse is stored in the electric/air conversion value storage section.

(2) Output =255 to the electric/pneumatic converter 10 and fully open the air operation regulator 9. If the paint color of the next workpiece is different from this time, drain the remaining paint in the paint supply passage 21 and clean the paint supply passage 21 with cleaning thinner.
Internal cleaning is required. Therefore, in order to reduce the flow resistance in the passage 21, the air-operated regulator 9 is fully opened.

(3) When a signal indicating the end of the cleaning process is received from the processing unit 1 of the automatic painting machine main body, -0 is output as the electric/pneumatic conversion value to the electric/pneumatic conversion device 10, and the air operation regulator 9 is fully opened. If the paint color of the 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.

(4) Complete the cycle 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 one-cycle correction start signal has been received. 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 the first step S5, -0 is output to the electric/pneumatic converter 1o to fully open the air operation regulator.Next, in step S6, the paint corresponding to the paint color is determined from the density table in the microcomputer 2. Read and set the density Ds(J), and then proceed to step s7.
Discharge that corresponds to the vehicle model, paint color, and discharge rate setting number!
Cent (volume flow rate) Qv (i, j, k). In the next step S8, the electric/pneumatic conversion value Ks (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 cented.

Next, in step S9, the volumetric flow rate Qv (r, j,
k) by the density Dij+ to obtain ffi! Convert to flow rate Q.

Then, in step SIO, (t, j, k) is output to the electric/pneumatic converter 10, and the above-mentioned initial process is completed.

Next, moving to FIG. 8, it is determined in step 311 whether or not the automatic coating machine RUN and ON signals have been received, and in the next step S12 it is determined whether or not the paint discharge ON signal has been received. If the discharge ON signal is received (time t in Fig. 5)
1), and τ in the next step 313. Wait for seconds. And τ. After seconds have elapsed, in step S14, the discharge amount is sampled based on the output of the mass flowmeter 4 (from time t2 to t3 in FIG. 5, sampling frequency fHz, sampling number S), and in the next step S15, the sampling result is Calculate the average mass flow rate, that is, the average discharge IQ. In the next step 316, Y=ζ□/Q for evaluation of the sampling data.

is calculated, and in the next step 317 it is determined whether the lever Y is within an allowable range. If the value of Y is outside the allowable range, the process proceeds to step 31B and the electric/pneumatic conversion value is corrected; however, if the value of Y is within the allowable range, the process proceeds to step 324 without making any correction and this K value is corrected. Value to electric/air converter 10
Output to. In step 318, it is determined whether Y is greater than 1 or less than l, and if Y>1, the correction valve ΔK is subtracted from the value of K in step S19 to
Correct the empty conversion value (T= - ΔK), and when Y<1, add the correction valve ΔK to the value of K in step S20 to correct the electric/air conversion value (T=+ΔK) 0 The next step S21 is a step of determining whether correction is possible or not, and O<T<
255, T-K in step S22 (correction possible)
When T≦ or T≧255, in step S23, it is set to =K (correction impossible), and in step S24
A secondary step S of outputting K to the electric/pneumatic converter 10 at
When the discharge OFF signal is detected at step 25 (time t4 in FIG.
), the process proceeds to step 326 to evaluate the automatic paint machine RUN signal. When this signal is ON, the process returns to step 312, and steps 513 to 324 are performed for the next paint flow pulse.
Perform the correction process shown in . When the automatic paint machine RUN signal is turned off (time t9 in FIG. 5), the electric/pneumatic conversion value table is rewritten in step S27 and the final correction chamber/air conversion value is stored. And paint supply passage 2
When the cleaning process signal is received regardless of the presence or absence of cleaning in Step 1, in step 328, =255 is output to the electric/pneumatic converter 10 to fully open the air operation regulator, and in step S1
Return to

The above is the flow of the process actually carried out by the microcomputer 2. As is clear from the above explanation, in this embodiment, there are a plurality of processes (12 for painting the top surface of the vehicle body,
For painting the side of the car body, since flow rate correction is performed for all 17 paint flow pulses, it is possible to make the paint film uniform. In addition, the correction data value of the final (12th or 177th) paint flow pulse 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 flow needle during operation of the automatic coating machine.
Figures A and B 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 explains the movement of the paint discharge nozzle of an automatic coating machine. Figures 10 and 11 are diagrams showing a spray painting method for an automobile body, Figure 12 is a diagram showing a spray painting method for an automobile body.
The figures each show the flow state of paint when painting the top and side surfaces of an automobile body. l...Automatic painting machine main body calculation processor 2...Microcomputer 3...Paint discharge nozzle 4--Mass flow meter 9-
Air-operated regulator lO--Electric/pneumatic conversion device 14-Color change valve group 15--Regulator group 16--Paint supply piping group

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 measured data with a reference value and corrects and controls the amount of paint discharged from the automatic coating machine based on this comparison, and corrects the paint flow rate for every paint flow pulse. A paint discharge amount control device characterized in that the correction data value of the final paint flow pulse in one painting cycle is used as an initial value for the next painting cycle.