JP4280560B2 - Coating film thickness measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a coating film thickness measuring device that measures film thickness data of a coating pattern when coating is performed under preset coating conditions by a film thickness sensor.
[0002]
[Prior art]
In painting lines such as automobile bodies, the position and orientation of the coating machine can be accurately controlled according to the complex surface shape of the object to be coated, so that high-quality coating films can be formed. A painting robot with a painting machine attached to the tip of the arm has been introduced.
[0003]
When painting using such a painting robot, set the movement route to move the coating machine, paint supply amount, rotary atomizing head drive air supply pressure, shaping for rotary atomizing type coating machine It is necessary to set coating conditions such as supply pressure.
[0004]
And in order to find the optimal coating conditions, it was traditionally repeated many times while changing the coating conditions little by little to determine the coating conditions that would give the best coating. Not only had to be used for experiments, but the painting experiment itself was too time consuming and labor intensive.
[0005]
For this reason, recently, the thickness of the coating film formed on the surface of the object to be coated when coated under the predetermined coating conditions is calculated by a computer, and the usable coating conditions are narrowed down. The painting conditions are determined through three painting experiments.
In this way, not only will the number of objects to be used for the experiment be reduced, but the number of painting experiments will be reduced, and the optimum coating conditions will be determined at a low cost and in a relatively short period of time. can do.
[Patent Document 1]
JP-A-9-75839 [0006]
By the way, when performing such a simulation, coating is performed on the basis of film thickness data obtained by converting the film thickness distribution per unit time of the coating pattern formed when the paint is supplied to the coating machine and applied at a fixed position. The thickness of the film is simulated.
Therefore, if the film thickness distribution per unit time can be obtained accurately, the thickness of the coating film can be simulated accurately.
[0007]
In this case, while measuring the film thickness of the coating pattern formed by painting the test piece placed on the coating machine for a preset coating time, based on the measured film thickness and the coating time The film thickness distribution per unit time is calculated.
[0008]
Conventionally, when a test piece on which a coating pattern is formed is placed on a stage and a film thickness sensor is disposed above the stage so that the film thickness sensor can be moved three-dimensionally, for example, when the diameter of the coating pattern is about 30 cm The measurement area is set to 40 cm × 40 cm, and the film thickness is measured by positioning the film thickness sensor on the measurement points set in a matrix shape with a 1 cm vertical and horizontal pitch within the measurement area, and positioning the film thickness sensor on the set measurement points. I have to.
[0009]
[Problems to be solved by the invention]
By the way, when measuring the film thickness of the coating pattern formed on the plurality of test pieces, it is necessary to keep the positional relationship of the measurement point with respect to the center of the coating pattern constant.
For this reason, conventionally, the dimensional accuracy of the test piece, the positional accuracy of the coating machine and the test piece at the time of painting, the positional accuracy of the test piece on the stage at the time of measurement are required. There was a problem that the experiment and the measurement test were troublesome.
[0010]
On the other hand, if the dimensional accuracy of the test piece is not required, the manufacturing cost can be reduced, and if the position accuracy is not required, the painting experiment and the measurement test are simplified, but the center point of the coating pattern every time the test piece is placed on the stage. This causes a problem that the position of the test piece or the orientation of the test piece changes.
In other words, even if the film thickness sensor is positioned at a matrix-shaped measurement point with a 1 cm vertical and horizontal pitch set in the same measurement area, the position of the measurement point is shifted each time, and each measurement point relative to the center of the coating pattern is shifted. Reproducibility cannot be obtained.
[0011]
Therefore, as a technical problem, the present invention makes it possible to measure the film thickness at a measurement point that is always in the same positional relationship with respect to the center of the coating pattern regardless of the dimensional accuracy of the test piece and the placement on the stage. Yes.
[0012]
[Means for Solving the Problems]
In order to solve this problem, the present invention places a test piece on which a coating pattern is formed on a stage when coating is performed under a preset coating condition by a stationary coating machine, and a film thickness sensor is set in advance. In a coating film thickness measurement apparatus that moves the measurement points on the machine coordinate system and measures the film thickness, an imaging camera that images the test piece from above the stage, and the film thickness sensor based on the image data A control device that sequentially measures the film thickness, and the control device is on a two-dimensional coordinate system for measurement with the center of the coating pattern formed on the test piece based on the image data as an origin. It has a calculation processing means for setting a measurement point and calculating the position of the measurement point in the machine coordinate system.
[0013]
According to the present invention, for example, when measuring the film thickness of a circular coating pattern formed by a rotary atomizing electrostatic coating machine, when a test piece on which a coating pattern is formed is placed on a stage, first the coating pattern is captured by an imaging device. Is captured and the image data is input to the control device.
[0014]
In the control device, first, a measurement two-dimensional coordinate system having the origin at the center of the coating pattern formed on the test piece is set based on the image data.
For the center coordinates of the paint pattern, for example, for the circular pattern obtained when the image data is binarized with a predetermined threshold, the center of the coordinates at the left and right ends and the center of the coordinates at the front and rear ends are calculated according to the machine coordinate system. To decide.
[0015]
Next, orthogonal coordinates parallel to the machine coordinate system are set with the center of the coating pattern as the origin.
In this case, for example, two positioning pins are arranged in the same direction on each of the coating stage on which the test piece is placed during painting and the stage on which the test piece is placed at the time of measurement, and one end edge of the test piece is always pressed against the positioning pin. By doing so, the orientation of the coating pattern is kept constant, and with this degree of alignment, accuracy is not required and manufacturing costs are not incurred.
Therefore, in this case, if only the center is specified and orthogonal coordinates passing through the center and parallel to the machine coordinate system are set as the measurement two-dimensional coordinate system, the relative positional relationship between the two-dimensional coordinate system and the coating pattern is Always constant.
[0016]
Also, if the positioning pin is provided only on the painting stand, the orientation of the painting pattern will not be constant just by placing the test piece on the stage, so one end that serves as an indicator of the orientation of the painting pattern on the test piece. If the edge is imaged with an imaging camera and the inclination angle of the measuring two-dimensional coordinate system with respect to the machine coordinate system is calculated based on the image data, the relative positional relationship between the two-dimensional coordinate system and the coating pattern is always constant. Become.
[0017]
Then, the film thickness sensor is moved to each measurement point by setting measurement points at predetermined intervals on the measurement two-dimensional coordinate system set in this way and calculating the position of each measurement point in the machine coordinate system. By measuring the film thickness data at the measurement point on the measurement two-dimensional coordinate system with the center of the paint pattern as the origin, the center of the paint pattern is maintained regardless of the dimensional error of the test piece or the spray position of the paint machine. On the other hand, the film thickness can be measured at measurement points that are in a certain positional relationship.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
1 is an explanatory view showing a coating film thickness measuring apparatus according to the present invention, FIG. 2 is an explanatory view showing a measurement principle by a film thickness sensor, FIG. 3 is an explanatory view showing two-dimensional coordinates for measurement and measurement points, and FIG. It is a flowchart which shows a process sequence.
[0019]
A coating film thickness measuring apparatus 1 shown in FIG. 1 places a test piece 3 on which a coating pattern P is formed on a stage 4 when a coating machine 2 is placed under a predetermined coating condition, and is provided above the stage 4. The obtained film thickness sensor 5 is moved to each measurement point M _n of the machine coordinate system XY set in advance, and the film thickness data is measured.
The coating film thickness measuring device 1 includes an imaging camera 6 that images the test piece 3 placed on the stage 4 and a control device 7 that measures the film thickness by sequentially positioning the film thickness sensor 5 based on the image data. And.
[0020]
In this example, a rotary atomizing electrostatic coating machine is used as the coating machine 2, and this coating machine 2 is installed at a predetermined distance from the coating table 8 on which the test piece 3 is fixed vertically downward. Has been.
The test piece 3 is formed in a substantially square shape, so that the right edge 3R serves as an index indicating the direction of the coating pattern so that the direction of the test piece 3 can be made constant when painting with the coating machine 2. The positioning can be performed by applying the right end edge 3R to the positioning pins 9 and 9 attached to the coating table 8 in a straight line.
Note that the positioning means is not limited to the pin 9, and any one such as a contact plate or a protrusion may be employed as long as the positioning is performed by bringing the right end edge 3 </ b> R into contact.
[0021]
A film thickness sensor 5 for measuring the film thickness of the coating pattern P is attached to an XY moving table 10 disposed above the stage 4 on which the test piece 3 is placed, and an arbitrary machine coordinate system X- is detected by a control signal from the driver 11. It can be positioned at the coordinates on Y.
Any film thickness sensor 5 can be used. In this example, as shown in FIG. 2, the test piece 3 is irradiated with laser light to detect the reflected light, and the sensor 5 and the test piece 3 are detected. The non-contact type sensor calculates the difference t between the clearance z _{1 of the} measurement point where the paint is not attached and the clearance z _{2 of the} measurement point where the paint is attached as the film thickness by accurately measuring the clearance of Is used.
[0022]
The measurement point M _n of the film thickness sensor 5 is calculated based on the image data of the coating pattern P captured by the imaging camera 6.
The imaging camera 6 is placed at a position a predetermined distance above the stage 4 on which the painted test piece 3 is placed, and in a direction in which the horizontal and vertical directions of the captured image data match the machine coordinate system XY. The image data of the coating pattern P of the test piece 3 placed on the stage 4 is captured and output to the control device 7.
[0023]
Based on the input image data, the control device 7 sets a measurement two-dimensional coordinate system xy with the center C of the coating pattern P formed on the test piece 3 as the origin, and the coordinate system xy After the measurement point M _n is set, the calculation processing means 12 for calculating the position of each measurement point M _{n in} the machine coordinate system XY and storing the coordinate data is included.
[0024]
FIG. 3 is a flowchart showing a processing procedure of the arithmetic processing means 12. First, the process waits until image data is input in step STP1, and when image data is input, the process proceeds to step STP2 and the machine coordinate system of the coating pattern P is displayed. The coordinates (X _c , Y _c ) of the center C in XY are calculated.
This process is based on the circular pattern obtained when the binarized image data with a predetermined threshold value, as shown in FIG. 4 (a), and the center X _c X coordinate of the left and right ends of the circular pattern, the front and rear determined by calculating the center Y _c across the Y coordinates.
[0025]
Next, in step STP3, as shown in FIG. 4B, an inclination angle θ between the right end edge 3R of the test piece 3 and the Y axis of the machine coordinate system XY is measured. The process of step STP3 corresponds to an angle adjusting unit.
In step STP4, as shown in FIG. 4C, based on the center C coordinates (X _c , Y _c ) of the coating pattern P calculated in step STP2 and the inclination angle θ measured in step STP3. Then, a measurement two-dimensional coordinate system xy inclined by an inclination angle θ is set with the center C as the origin.
Note that if the positioning pins 9 and 9 are also provided on the stage 4 on which the test piece 3 is placed, the tilt does not occur, so that the process of step STP3 is not necessary.
[0026]
Next, the process proceeds to step STP5, and measurement points M _n (x _n , y _n ) are set on the respective lattice points of the measurement two-dimensional coordinate system xy set in this way. In step STP6, each measurement is performed. The coordinate value of the point M _{n in} the machine coordinate system XY is calculated, the coordinate data (X _n , Y _n ) is stored in a predetermined storage area, and the process is terminated.
[0027]
After the coordinate data (X _n , Y _n ) of each measurement point M _n is set in this way, the coordinate data (X _n , Y _n ) are sequentially read out and output to the driver 11, so that the XY table 10 Is moved, and the film thickness sensor 5 is sequentially positioned at each measurement point M _n (X _n , Y _n ).
Therefore, regardless of the dimensional error of the test piece 3 or the spray position of the coating machine 2, the film thickness can be measured at the measurement point M _n that is always in a fixed positional relationship with respect to the center of the coating pattern P.
[0028]
The machine coordinate system and the measurement two-dimensional coordinate system are not limited to orthogonal coordinates, and any two-dimensional coordinate system such as polar coordinates can be adopted.
Further, the film thickness sensor is not limited to a non-contact type, and a contact type three-dimensional probe or the like can also be adopted.
[0029]
【The invention's effect】
As described above, according to the present invention, since the two-dimensional coordinate system for measurement passing through the center is set based on the image data of the imaged coating pattern, the dimensional accuracy of the test piece and the stage Regardless of how it is placed, the film thickness at the measurement point always in the same positional relationship with respect to the center of the coating pattern can be measured.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a coating film thickness measuring apparatus according to the present invention.
FIG. 2 is an explanatory diagram illustrating a measurement principle using a film thickness sensor.
FIG. 3 is a flowchart showing a processing procedure.
FIG. 4 is an explanatory diagram showing two-dimensional coordinates for measurement and measurement points.
[Explanation of symbols]
1 ... Coating film thickness measuring device 2 ... Coating machine P ... Painting pattern 3 ... Test piece 3R ... Right edge (index)
4 ......... Stage 5 ......... Film thickness sensor XY ......... Machine coordinate system xy ......... Measurement two-dimensional coordinate system _Mn ......... Measurement point 6 ......... Imaging camera 7 ......... Control device 10... XY movement table 12.

Claims (2)

Place a test piece on which a coating pattern is formed when painting under a preset coating condition with a stationary coating machine on the stage, and move the film thickness sensor to each measurement point in the preset machine coordinate system. In the coating film thickness measuring device that measures the film thickness,
An imaging camera that images the test piece from above the stage, and a controller that sequentially measures the film thickness sensor based on the image data to measure the film thickness,
The control device sets a measurement point on a measurement two-dimensional coordinate system with the origin of the center of the coating pattern formed on the test piece based on the image data, and sets the position of the measurement point in the machine coordinate system. An apparatus for measuring a coating film thickness, comprising an arithmetic processing means for calculating. An index indicating the orientation of the paint pattern is formed on the test piece, and the control device calculates an inclination angle of the measurement two-dimensional coordinate system with respect to the machine coordinate system based on image data of the index imaged by the imaging camera. The coating film thickness measuring apparatus according to claim 1, further comprising an angle adjusting means.

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