JPS63158160A - Method for controlling lateral flow of air stream in painting booth - Google Patents

Abstract

PURPOSE:To suppress the lateral flow of the air stream in a painting booth to a definite value or less, by regulating air supply/discharge quantity according to the temp. difference between the inside and outside of the painting booth and performing control so that the intersecting point of the air supply/discharge quantity and the temp. difference between the inside and outside of the booth does not exceed a limit line. CONSTITUTION:An internal temp. sensor 16 and an external temp. sensor 17 are respectively provided to the inside and outside of a painting booth 1, and the temp. difference between the inside and outside of the booth 1 is always detected by an operator 18; when said temp. difference exceeds a definite range, an alarm is emitted from an alarm device 19. A worker operates a variable blade opening degree indicator 14 on the basis of said alarm while confirms a variable blade opening degree display device 15 to alter the variable blade opening degree of an air supply fan 2 to bring the temp. difference to the state within a security range. In addition thereto, the worker operates a damper opening degree indicator 21 while confirming a current value display device 23 so as to set the current value of a discharge fan motor to a predetermined value to alter the opening degree of a discharge damper 20 to take the balance of air supply/discharge quantity.

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention provides a spray painting booth with downward ventilation system.
This invention relates to a method for controlling the lateral flow of air in a painting booth, which controls the amount of lateral air flow within the painting booth to a certain value or less in order to prevent paint mist from scattering and expanding to the surrounding area due to the lateral flow K of the air in the painting booth.

``Prior Art'' When performing spray painting, a paint booth shielded from the outside world is provided, and the painting work is performed within this paint booth. In order to exhaust the dirty air inside the painting booth to the outside,
The painting booth is equipped with an air supply fan and an exhaust fan so that air flows vertically from top to bottom within the painting booth.

In FIGS. 7 and 8, 1 is a painting booth, 2 is an air supply fan, 3 is an air supply chamber, 4 is a work floor having a slatted opening, 5 is an exhaust chamber, and 6 is an exhaust fan, The painting gun 7 is used to spray paint the inner surface of the lower end of the back door 8. If the airflow 9 flows vertically as shown in FIG. 7, the paint mist 10 will not scatter to other painted finished products 11, but as shown in FIG. If the paint mist 10 does not flow horizontally but instead flows laterally with a horizontal velocity distribution, the paint mist 10 may scatter until it reaches other coated finished products 11, resulting in product defects.

In order to know whether there is a lateral flow of air flow 9 like jin, it is necessary to
Using a lateral flow evaluation gauge 12 as shown in the figure, a kite string 15 was brought down to near the work floor 4, and the displacement y with respect to the vertical direction was evaluated.

``Problems to be Solved by the Invention'' Conventionally, the cause of the crossflow phenomenon occurring in the airflow 9 in the coating booth 1 is due to fluctuations in the supply air volume and exhaust air volume in the entire area or part of the coating booth 1. It was believed that this was caused by an imbalance in the exhaust air volume, and the equipment design standards for preventing cross-flow of air in the paint booth only stipulated the method to ensure a balance in the air supply and exhaust air volume and the method to maintain it.

However, even if the supply and exhaust air volume to the painting booth was balanced and the airflow was once in a good condition with only vertical airflow with no horizontal flow, no fluctuations in the supply and exhaust air volume were observed within a few hours. Nevertheless, large amounts of crossflow sometimes occurred.

As a result of investigating the cause of this, it was found that the above-mentioned short-term fluctuations in airflow were largely influenced by fluctuations in the temperature difference between the inside and outside of the painting booth. In line experiments, it was confirmed that by adjusting the amount of air supplied and exhausted from the paint booth according to the temperature difference, cross-flow inside the paint booth can be suppressed.

This invention provides a painting booth that controls the cross-flow of air within the painting booth to below a certain value by adjusting the supply and exhaust air volume, which is a control factor, in accordance with fluctuations in the temperature difference inside and outside the painting booth, which is a non-controllable factor. It is an object of the present invention to provide a method for controlling the lateral flow of internal airflow.

``Means for Solving the Problems'' This invention calculates the relationship between the lateral flow rate of the airflow inside the painting booth, the supply/exhaust air volume, and the temperature difference between the inside and outside of the painting booth in a downward ventilation type spray painting booth, and calculates the allowable lateral flow rate. By deriving the relationship between the supply and exhaust air volume at the limit and the temperature difference inside and outside the painting booth, and setting this as the limit line, and adjusting the supply and exhaust air volume according to fluctuations in the temperature difference between the inside and outside of the painting booth, the supply and exhaust air volume This is a cross-flow control method for airflow in a painting booth, characterized in that the intersection point of the temperature difference between inside and outside of the painting booth is controlled so as not to exceed the limit line.

``Function'' Adjust the air supply and exhaust air volume according to changes in the temperature difference inside and outside the painting booth, and control so that the intersection of the air supply and exhaust air volume and the temperature difference inside and outside the painting booth does not exceed the limit line. The horizontal flow of the airflow becomes controlled below a certain value.

"Example" Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a system diagram for controlling the supply and exhaust air volume for the painting booth 1 to which the present invention is applied, in which the rotary blades of the air supply fan 20 (not shown) are variable blades that can adjust the air supply volume to the painting booth 1 by changing the opening degree. , and the variable blade opening indicator 1
4 indicates the opening, and the variable blade opening display 15 displays the actual opening of the variable blade.

An internal temperature sensor 16 is provided inside the coating booth 1, and an external temperature sensor 17 is provided outside the coating booth 1.
8, it is always detected. If the temperature difference inside and outside of the painting booth 1 exceeds a certain range described later,
The alarm device 19 is instructed to issue an alarm.

An exhaust damper 20 is installed between the painting booth 1 and the exhaust fan 6.
is provided, so that the opening degree of the exhaust damper 20 can be changed by a motor 22 that is operated according to instructions from a damper opening degree indicator 21. When the opening degree of the exhaust damper 20 is changed, the load on the exhaust fan 6 changes, and the current value of the exhaust fan motor that rotates the exhaust fan 6 changes. This current value is K as displayed on the current value display 23.

As described above, by operating the damper opening degree indicator 21 to change the opening degree of the exhaust damper 20, the current value of the exhaust 7 motor can be indirectly controlled within a certain range.

Fluctuations and airflow 9 of all factors that are thought to affect the lateral flow of airflow 9 in the painting booth as shown in Figure 8
The following relational expression was obtained as a result of continuous evaluation of the fluctuation status of the cross flow within the painting line and statistical processing.

y = 4.104x, -4,129x, -1166x
, -2,197x4+165924...
...C formula 1) y:! ! Amount of horizontal air flow inside the installation booth (number) xl: Supply fan variable blade opening (%) x,: Exhaust fan motor current value (ampere) x, Opening ratio of work floor 4 (%) Temperature difference inside and outside the booth (temperature inside the painting booth - temperature outside the painting booth) (°C) The exhaust 7 unmotor current value
stand).

x,=cL225x1+52.245 pieces of music (Formula 2) This formula 2 is shown in a graph as shown in FIG.

In addition, since the opening ratio X of the work floor 4 is actually a fixed condition, assuming these conditions, the supply air 7 am variable blade opening X0 at the permissible limit of the lateral flow amount y of the airflow inside the painting booth
The relationship between and the temperature difference inside and outside the painting booth, X, can be derived.

That is, xl= [lL692 X4 + 72.944...
-・-(Equation 3) This equation 3 is shown in a graph as shown in Fig. 2. This limit line and the constant value required to obtain the minimum required wind speed for the painting booth shown by the dashed line in Fig. 2. The parallel hatched area between the horizontal line indicating the variable air supply fan blade opening is
This is a practical guarantee range that can guarantee that the paint mist 10 will not be scattered to other painted finished products 11. In addition, the two-dot chain line in FIG. 2 shows the steady operation reference value of the air supply 7-amp variable blade opening x0.

In Figure 4, which is shown using the same coordinates as Figure 2, the temperature difference between the inside and outside of the painting booth, X, fluctuates from the condition of the supply air 7-amp variable blade opening indicated by point A, x0, and the temperature difference inside and outside of the painting booth. When point B is out of range (crosses the limit line),
Calculator 18 calculates the difference in temperature between inside and outside of the painting booth,
It is detected that the vehicle is out of the guaranteed range, and the alarm device 19 issues an alarm. This alarm causes the operator to check the variable blade opening indicator 15 while checking the variable blade opening indicator 15.
4 to change the intake fan variable blade opening x0, and
As shown in the figure, from the state of point B which is outside the warranty range,
Set the condition to point C, which is within the warranty range. In addition, as shown in Fig. 6 using the same coordinates as Fig. 3, the exhaust fan motor current value
The current value display 25 is set so that
While checking this, operate the damper opening indicator 21 to change the opening of the exhaust damper 20 and adjust the amount of air supply and exhaust. Due to this K, short-term airflow fluctuations within the coating booth 1 are suppressed, and the lateral flow of the airflow is controlled to be below a certain value.

In addition, when the temperature difference x4 inside and outside the painting booth returns to within the guaranteed range at the steady operation standard value of the supply air fan variable blade opening x0, the setting of the supply air 7 Anne variable blade opening x0 is returned to the steady operation standard value. .

Of course, the air supply fan variable blade opening X should be set to the standard operating value within the guaranteed range, and when the temperature difference between the inside and outside of the painting booth, X, reaches the limit line, the air supply fan It is also possible to automatically control the variable blade opening x1.

"Effects of the Invention" According to the present invention, it is possible to control the cross-flow of air inside the painting booth, which is caused by the temperature difference inside and outside the painting booth, to below a certain value, and it is possible to perform painting work with a good finish. can.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an embodiment of the present invention, Fig. 2 is a graph showing the relationship between the temperature difference inside and outside the painting booth and the supply air 7-amp variable blade opening, and Fig. 3 is a graph showing the variable air supply fan blade opening. Figures 7 and 8 are vertical side views of the paint booth, and Figure 9 is a side view of the lateral flow evaluation gauge. 1...Painting booth 2...Air supply fan 6...
Exhaust fan 14...Variable blade opening indicator 16...
・Internal temperature sensor 17...External temperature sensor 23...Current value display Patent applicant Toyota Auto Body Co., Ltd. Figure 2 Figure 7 Section 4 Figure 611J Figure 8

Claims (1)

[Claims] 1) In a spray painting booth with a downward ventilation system, find the relationship between the horizontal flow rate of the airflow inside the painting booth, the supply and exhaust air volume, and the temperature difference inside and outside the painting booth, and calculate the relationship between the supply and exhaust air volume and the temperature difference inside and outside the painting booth at the permissible limit of the horizontal flow rate. By deriving the relationship and setting this as a limit line, and adjusting the air supply and exhaust air volume according to fluctuations in the temperature difference inside and outside the painting booth, the intersection of the air supply and exhaust air volume and the temperature difference inside and outside the painting booth will not exceed the limit line. A lateral flow control method for airflow in a painting booth, characterized in that the airflow is controlled as follows.