JP3031587B2 - Overspray width control device for automatic electrostatic coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling an overspray width in an automatic electrostatic coating apparatus, and an empirical rule for applying a good coating corresponding to a specific shape element of each object to be coated. Automatic spray coating device that infers the optimum overspray width for each object to be coated based on the overspray control rules based on the above and the membership functions of the fuzzy variables that make up the rules, and outputs the results Overspray width control device.

[0002]

2. Description of the Related Art Conventionally, as an automatic electrostatic coating apparatus, a spray gun which reciprocates up and down by a reciprocator is provided near a conveyor for horizontally transferring an object to be coated, and the object to be coated is located in front of a coating position. A spray sensor is provided to detect the front shape of the object, and when the object to be coated is conveyed to the painting position, the spray gun is controlled so as to spray the paint in a range corresponding to the front shape of the object to be coated, and is ejected. It is known that the applied paint is applied to the object by the action of an electrostatic field formed between the spray gun and the object.

On the other hand, in the case of electrostatic coating, when the object to be coated is box-shaped as shown in FIG. In other words, a method is adopted in which the paint is wrapped around the peripheral surface by spraying the paint over a larger area than the front shape to apply the paint, and this is partially incorporated into the automatic electrostatic coating as described above. Have been done.

At this time, it is needless to say that the width of the overspray needs to be adjusted according to the depth of the object to be coated. Further, for example, as shown in FIG. In such a case, the coating area on the peripheral surface is increased compared to the front square type without such a concave portion, while the peripheral surface of the object to be coated is part of the paint blown to the front. Considering that the wraparound is applied, the amount of paint that is blown, that is, the amount of paint that goes to the peripheral surface side is reduced because the front area is reduced by providing the concave portion, so it is covered. It is also known from experience that it is necessary to change the overspray width depending on the shape of the front surface of the object to be coated, for example, by increasing the width of the overspray.

[0005]

In the conventional automatic electrostatic coating that employs overspray, the setting of the overspray width is performed manually.
In other words, before the workpiece reaches the coating position, the operator checked the depth and frontal shape of each workpiece and set the overspray width each time by experience, so that it was completely automated. However, there was a drawback that stable painting could not be expected.

[0006]

Overspray width control system for an automatic electrostatic coating apparatus of the present invention According to an aspect of the shall apply has been accomplished in view of the points on ordination, and depth with the object to be coated, the target
Detecting means for detecting information representing a unique shape element determined by the area occupancy of the front shape of the painted object; storing means for storing a control rule based on an empirical rule for obtaining an overspray width for the information; Computing means for computing an overspray width given to the spray gun control unit by fuzzy logic operation based on the information detected by the means and the control rules retrieved from the storage means. Here, the area occupancy is the front of the object
The maximum vertical dimension of the shape is multiplied by the maximum horizontal dimension.
Is defined as the ratio of the actual painted area.

[0007]

When information representing a unique shape element possessed by the object to be coated is detected by the detecting means, based on the detected information and a control rule based on an empirical rule stored in advance in the storing means, A fuzzy logic operation is executed by the arithmetic means,
An overspray width to be given to the spray gun control unit is required.

[0008]

An embodiment of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a reciprocator 3 for suspending a workpiece a at a predetermined interval and transporting the workpiece a in a direction indicated by an arrow, in the vicinity of which a spray gun 2 is attached to reciprocate up and down. Is provided, the spray gun 2 is connected to the negative electrode of a high-voltage generator (not shown), the conveyor 1 is grounded, and a high-potential electrostatic field is generated between the spray gun 2 and the workpiece a. The paint formed and ejected from the spray gun 2 is applied to the workpiece a by the action of the electrostatic field.

A front sensor 5 for detecting the front shape of the object to be coated a is provided at a detection position provided at a predetermined distance before the painting position. The front sensor 5 includes, for example, a large number of image sensors. The vertical dimension of the object to be coated a is sequentially read from the front in the traveling direction, and a pulse having a cycle synchronized with the traveling speed of the conveyor 1 is transmitted as shown in FIG. In combination with a pulse transmitted from the pulse encoder 6, the shape capturing unit 7 captures the front shape of the workpiece a as a detection signal.

[0010] A pattern calculation unit 8 is connected to the shape capturing unit 7 to calculate a spray pattern corresponding to the detected front shape, and more specifically, an overspray pattern calculated by an overspray width control device 10 described later. The width is added, the correction pattern is calculated by the correction pattern calculation unit 11, and the output signal is sent to the spray gun control unit 12 that controls the spraying and stopping of the paint from the spray gun 2. I have.

Next, an overspray width control device which is a feature of the present invention will be described. In the present embodiment, the depth of the object to be coated a and the area occupancy of the front shape of the object to be coated a are selected as the unique shape factors that determine the overspray width. This area occupancy is, as shown in FIG.
The ratio of the actual coating area (a ₂ : solid line portion) to the square area (a ₁ : broken line portion) obtained by multiplying the maximum vertical dimension of the front shape of the workpiece a by the maximum horizontal dimension, that is, the area occupation Rate = (a ₂ / a ₁ ) × 100 (%).

As described above, the selection of the area occupation ratio is as follows. When the object a has a concave portion, the coating area on the peripheral surface increases, and the absolute amount of the paint wrapping around the peripheral surface decreases. In view of the necessity of increasing the overspray width, this is selected as a means for simulating that it is necessary to increase the overspray width as the area of the concave portion increases, that is, as the area occupation ratio decreases.

In view of this, the overspray width control device 10 according to the present embodiment includes, as shown in FIG.
The above-described front sensor 5, pulse encoder 6, shape capturing unit 7, feature extracting unit 14, and microprocessor 15
It is composed of

As shown in FIG. 1, the depth sensor 13 is installed above the conveyor 1 in the vicinity of the front sensor 5 described above, and the object to be coated is formed by a number of image pickup devices arranged at right angles to the conveyor 1. The depth of a is detected.

The feature extracting unit 14 is provided with the above-described depth sensor 13.
The depth of the object to be coated a is calculated based on the detection signal from
In addition, the area occupancy is calculated from the detection signal of the front shape taken into the shape taking section 7 by the front sensor 5.

The microprocessor 15 comprises a fuzzy inference processor 16 and a control rule storage 17. The fuzzy inference processor 16 infers the overspray width in accordance with the procedure described later, using the calculation data on the depth and the area occupancy of the object a from the feature extraction unit 14, and sends it to the correction pattern calculation unit 11. Output. The control rule storage unit 17 is for storing control rules necessary for the fuzzy inference executed by the fuzzy inference processor 16.

The above-mentioned fuzzy inference for obtaining the overspray width is executed based on the following nine control rules. R ₁ : If the depth is large and the area occupancy is large,
Increase the overspray width. R ₂ : If the depth is small and the area occupancy is large,
Make the overspray width very narrow. :: Etc.

These rules are control rules for the optimum overspray width based on the shape elements of the object to be coated, obtained by the inventors based on empirical rules obtained from numerous experimental data. Table 1 shows the relationship between the depth of the object and the area occupancy.

[0019]

[Table 1]

Table 1 shows that the depth X of the object to be coated is divided into three stages (small = S, medium = M, large = L) in the vertical direction and the area occupancy Y in the horizontal direction. In the same manner as the above-described depth, they are arranged in three stages (small = S, medium = M, large = L), and the positions where the above-mentioned divided depth and area occupancy intersect are respectively the depth and the depth. The optimal overspray width Z corresponding to the area occupancy is divided into one of five stages (minimum = VN, small = N, medium = M, large = W, maximum = VW) according to the size. I am applying.

That is, the above-mentioned control rule R ₁ is indicated by a cell (R ₁ ) in Table 1, the control rule R ₂ is indicated by a cell (R ₂ ) in the table, and the control rule R ₃ is indicated by a cell (R ₃ )
Indicated by

When the above-mentioned language rule is stored in the control rule storage unit 17 shown in FIG. 2, it is stored according to the following nine rule rules.

R ₁ : If X is LX and Y is LY then Z is WR R ₂ : If X is SX and Y is LY then Z is VN::

The overspray width control device having the above-described structure operates as follows. When the object a passes the detection position, the depth of the object a is detected by the depth sensor 13, and the front shape of the object a is captured by the shape capturing unit 7 via the front sensor 5. Each detection signal is output to the feature extraction unit 14 to calculate the depth and the area occupancy,
The calculation result is output to the fuzzy inference processor 16 of the processor 15.

The above-mentioned rules of R ₁ , R ₂ ‥‥ R ₉ stipulate that the depth, the area occupancy and the size of the overspray width are
Since the overspray width is finely controlled as shown in Table 1, in order to perform fine control of the overspray width, the above-described control is performed with the above-described depth and area occupancy measured in the actually measured depth and area occupancy. It is necessary to calculate the degree to which the antecedent part (If part) of the rule R is satisfied, and estimate the overspray width according to the degree.

For this reason, in the present embodiment, the above degree is calculated using a membership function of a fuzzy variable with respect to the depth, the area occupancy and the overspray width.

FIG. 4A shows the membership functions μSX (x) of the fuzzy variables SX, MX and LX with respect to the depth X.
μMX (x) and μLX (x) are shown in FIG.
Are the fuzzy variables SY, MY, L for the area occupancy Y.
This shows the membership functions μSY (y), μMY (y), and μLY (y) of Y. FIG. 3C shows the membership functions μVN (Z), μN (Z), μM (Z), μM (Z), μW (Z) of the fuzzy variables VN, N, M, W and VW with respect to the overspray width Z.
It shows VW (Z).

The fuzzy inference executed by the fuzzy inference processor 16 is based on the above control rules R ₁ , R ₂ ‥‥ R ₉
And a member logic function shown in FIGS. 4A, 4B, and 4C to perform a fuzzy logic operation to calculate an overspray width.

FIG. 5 shows a flow chart of the inference. In step S _1, a depth sensor 13, based on the detection signal from the front sensor 5 and the shape acquisition unit 7 calculates the measurement data x _0, y ₀ the depth and area occupancy by the feature extraction unit 14.

[0030] In step S _2, Yotsute the fuzzy inference processor 16, the depth, with (indicated by M function in the figure) the membership function of the fuzzy variables to the area occupancy, the membership value in the measured data x _0, y ₀ (Shown as M value in the figure).

In step S ₃ , the degree to which the obtained depth and area occupancy membership values satisfy the antecedents of the above nine rules is determined by the following equations (1) and (2). It is calculated by the fuzzy logical product as in ‥.
In FIG. 5, the fuzzy variable for the depth is indicated by P, and the fuzzy variable for the area occupancy is indicated by Q.

[0032]

(Equation 1)

(Equation 2) :::

[0033] Here, Equation 1 enters the region LX is the depth x ₀ of the measured relative depth, and the proposition that the area occupation ratio y ₀ of the measured enters the area LY to the area occupancy, x ₀ is the LX the degree entering, that y ₀ is established at the degree of a smaller value of the degree entering LY, in other words, the depth x _0, when the area occupancy y _0, control rules R ₁
Antecedent part of denotes that holds the degree of D _1. Similarly, Equation 2 indicates that when the depth x ₀ and the area occupancy y ₀ , the antecedent of the control rule R ₂ is satisfied with the degree D ₂ .

[0034] In step S _4, if satisfied antecedent of control rule Rn of one as described above is the degree Dn, since the execution of the rule (the Then section) is also satisfied in degree of Dn, each control rule The degree Dn at which the antecedent part is established for each is determined by the fuzzy variables (VN, N, M, W,
The membership function of the execution unit is corrected by multiplying the membership function of VW) by the following equation.

[0035]

(Equation 3)

(Equation 4) :::

[0036] In step S _5, Yotsute to the membership function of the execution of the above modified control rules, said depth x _0, the overspray width Z ₀ of the optimal control system of area occupancy y ₀ following It is requested as follows.

In order to obtain the overspray width Z ₀ , first, the logical sum of the corrected membership function of the execution unit of each control rule obtained as described above is taken, and all rules are obtained as in the following equation (5). Find the general membership function of the execution part of.

[0038]

(Equation 5)

Equation 5 indicates that the measured depth of the object to be coated is x ₀ ,
When the area occupancy is y ₀ , the optimal overspray width Z ₀
Is expressed as a function of the width.

Next, as shown in Equation 6, the overspray width Z ₀ is obtained by weighting and averaging the overspray width of the fuzzy variable of the general membership function with the degree (ie, the membership value) belonging to the general membership function.

[0041]

(Equation 6)

As described above, the overspray width obtained by the overspray width control device 10 is output to the correction pattern calculation unit 11 as shown in FIG. A correction pattern is calculated by adding an overspray width to a spray pattern corresponding to the front shape of FIG.
Is delayed by the delay circuit 18 which operates in response to the pulse from the detection position, and is output to the spray gun control unit 12 after being transported from the detection position to the coating position, and is transferred to the coating position. When it comes, the spraying and stopping of the paint from the spray gun 2 are controlled based on the correction pattern.

As described above, in this embodiment, the overspray width can be finely controlled by using the depth and the area occupancy of the object to be coated a as control parameters, and the control rule is made up of empirical rules obtained through repeated experiments. As a result, it is possible to always control the overspray width to the optimum, and to perform good automatic electrostatic coating.

In the above embodiment, the depth and the area occupancy are selected as the information of the shape elements for determining the overspray width, but the present invention is not limited to this.

[0045]

As described above in detail, according to the present invention, the overspray width of each object to be coated is automatically controlled, and a completely automatic electrostatic coating can be realized. Moreover,
The control is based on information on the unique shape elements of each workpiece,
It is performed based on the result of fuzzy logic operation from control rules based on empirical rules, so fine and accurate control is possible, and it is possible to apply the optimal coating corresponding to the shape of each workpiece, The same control is always performed for objects to be coated having the same shape, and there is an effect that a product with a constant quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view of an automatic electrostatic coating apparatus according to the present invention.

FIG. 2 is a block diagram of one embodiment of the present invention.

FIG. 3 is an explanatory diagram of an area occupancy of an object to be coated.

FIG. 4A is a diagram showing a membership function of a fuzzy variable with respect to the depth of an object to be coated.

FIG. 4B is a diagram showing a membership function of a fuzzy variable with respect to an area occupancy of an object to be coated.

FIG. 4C shows a membership function of a fuzzy variable with respect to an overspray width.

FIG. 5 is a flowchart of fuzzy inference.

[Explanation of symbols]

a: object to be coated 1: conveyor 2: spray gun 3: reciprocator 5: front sensor 6: pulse encoder 7: shape capture unit 10: overspray width control unit 12: spray gun control unit 13: depth sensor 1
4: Feature extraction unit 15: Microprocessor 16: Control rule storage unit
17: Fujii Inference Processor

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B05B 5/025 B05B 12/00 B05B 13/04 B05D 1/02

Claims (1)

(57) [Claims] A spray gun reciprocating up and down by a reciprocator is provided in the vicinity of a conveyor for horizontally conveying an object to be coated, and a spray gun is provided when the object to be coated is conveyed to the front of the spray gun. For the spray gun control unit that controls the spraying and stopping of the paint from the surface, an overspray width corresponding to the unique shape element of the object is added to the range corresponding to the front shape of the object. A control signal is issued so that the paint is ejected within the range, and the ejected paint is applied to the object by the action of the electrostatic field formed between the spray gun and the object. An apparatus for controlling the overspray width of a coating apparatus, comprising: a depth of the object to be coated;
Detecting means for detecting information representing a shape element determined by a prevailing ratio ; storing means for storing a control rule based on an empirical rule for obtaining the overspray width for the information; and detecting means for detecting the information. Computing means for computing an overspray width to be given to the spray gun control unit by fuzzy logic operation based on the information and the control rules retrieved from the storage means. Overspray width control device for electrostatic coating equipment.