JPH11267992A - Teaching method of painting robot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To paint while maintaining a gun distance, painting pitch and gun angle fixedly with a few manhour respectively. SOLUTION: In the off-line teaching method of a painting robot using CAD data of a painted article, the imaginary planes of horizontal and vertical directions for the three dimensional surface data of the painted article are interfered and plural interfere lines of horizontal and vertical directions are extracted (S1-S4). The coordinates of respective cross points of these interfere lines are calculated and a plane equation constituted by two interfere lines is calculated at respective cross points and the straight line orthogonally crossing with this plane is calculated (S5-S6). The three dimensional coordinates of the point separated by a prescribed distance in the vertical direction is calculated at respective cross points and the obtained point is made to a teaching point (S7).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of teaching (hereinafter, also referred to as "teaching") a painting robot applied to painting of an automobile body or an automobile part, and more particularly to a method of applying an intermediate coating robot or a top coating robot. It relates to an offline teaching method.

[0002]

2. Description of the Related Art In a painting factory for automobile bodies and automobile parts, a large number of painting robots are introduced for the purpose of improving productivity and working environment, but on the other hand, there are problems such as an increase in teaching accuracy and teaching man-hours. Has become apparent. Therefore, a CAD teaching method for teaching a painting robot using computer simulation has been proposed.

[0003] By the way, items to be pointed out when teaching the top coating robot are a gun distance, a coating pitch and a gun angle.

That is, when a flat plate W is painted using a bell-shaped painting gun or the like, it is general that the painting is performed according to the gun locus as shown in FIG. The solid line shown in FIG.
N, dotted line indicates paint OFF. In this case, if the distance between the flat plate (object to be coated) W and the gun is too far from the specified value, it becomes a thin film and the coating quality is reduced, the coating efficiency is reduced and the amount of paint used is increased. Conversely, if the distance between the object to be coated W and the gun is too close to the specified value, the film becomes thick and sags. Therefore, the gun distance L needs to be maintained at a certain distance that is related to the amount of paint discharged.

In the case of painting with a gun locus as shown in the figure, the interval between adjacent locus, that is, the painting pitch P
If the value is too narrow than the specified value, the overcoating area becomes wide and the film becomes thick, causing sagging, or the gun needs to be operated many times to paint the same area, thereby increasing the cycle time. Conversely, if the coating pitch P is too wide than the specified value, the coating range becomes narrow and the coating becomes thin, resulting in poor coating quality. Therefore, the coating pitch P needs to maintain a constant value that is related to the pattern width of the gun, the discharge amount of the paint, and the like.

Since a bell-shaped coating gun or the like is discharged in a circular pattern, if the axial direction of the gun is not perpendicular to the surface of the workpiece W as shown in FIG. Since the pattern region close to the substrate becomes a thick film and the pattern region far from the substrate becomes a thin film, the film thickness becomes nonuniform as a whole to be coated, and problems such as uneven coating occur. Therefore, the object to be coated W
Is also required to be in the vicinity of the plane.

When performing CAD teaching of a coating robot in consideration of these important items, there is no particular problem when the object to be coated W is a flat plate as described above, but the body of the automobile has a complicated curved surface. However, even in such a case, it is necessary to paint while keeping the gun distance L, the painting pitch P and the gun angle α constant.

The conventional method will be described with reference to a door outer panel as an example. As shown in FIG. 11, first, in order to create a teaching point on CAD data W _CAD of a door outer panel which is an object to be coated W, the same operation is performed. A vertical line 11 and a horizontal line 12 are drawn as shown in FIG. At this time, the interval between lines to be drawn (horizontal line 12 in this case) is reduced in a portion where the curvature of the door is large so that the gun angle is straight at any teaching point. Next, an intersection 13 of the vertical line 11 and the horizontal line 12 drawn as shown in FIG. 2B is picked (extracted) with a touch pen, and the intersection 13 is set as a teaching point. When one teaching point is determined in this way, the three-dimensional coordinate system at the teaching point is manually specified as shown in FIG. That is, as shown, the directions of the X, Y, and Z axes (that is, either the + direction or the-direction) are manually specified such that the Z axis is straight. Repeat the above operation for all intersections 1
3, and finally, the gun distance L is input in the Z-axis direction, and the points are connected to form a trajectory of the gun.

[0009]

However, in the above-described conventional teaching method, the operator picks an intersection 13 between the vertical line 11 and the horizontal line 12 on the screen on which the CAD data is displayed by using a touch pen, and the operator touches the intersection. To extract
It is not uncommon for some deviation to occur. Even a slight deviation on the screen can reach several centimeters when it becomes a real vehicle. Due to such an error, the coating pitch P
Is not in a constant range, and the above-described variation in the overcoating range causes unevenness in film thickness.

The operation of determining the X, Y, and Z directions (three-dimensional coordinate system) at the intersection 13 between the vertical line 11 and the horizontal line 12 is also performed manually by the operator. Often include large errors. Also in this case, the condition for maintaining the gun angle α straight is not satisfied, and there is a possibility that a coating failure due to uneven film thickness may occur.

[0011] Further, such manual teaching takes an extremely long time, and if the teaching result is not satisfactory, it is necessary to search for a teaching point having a defect and correct it, which requires a large number of man-hours. Was something.

The present invention has been made in view of the above-mentioned problems of the prior art, and has a small man-hour, a short gun distance,
An object of the present invention is to provide a painting robot teaching method capable of performing painting while maintaining the painting pitch and the gun angle constant.

[0013]

According to a first aspect of the present invention, there is provided a method for teaching a painting robot, wherein three-dimensional coordinates of a teaching point of the painting robot are determined by using three-dimensional surface data of an object to be coated. In the teaching method of the coating robot to be determined, the virtual plane in the first direction is caused to interfere with the three-dimensional surface data of the object to be coated, and the virtual plane in the first direction is made to intersect the second direction orthogonal to the first direction. Moving at an arbitrary pitch to extract respective interference lines between the three-dimensional surface data of the object to be coated and the virtual plane in the first direction; and Interfere with the virtual plane in the second direction,
Moving the virtual plane in the second direction at an arbitrary pitch in the first direction, and extracting respective interference lines between the three-dimensional surface data of the object to be coated and the virtual plane in the second direction;
Calculating the coordinates of each intersection of the first direction interference line and the second direction interference line extracted in the two steps, and calculating a plane equation composed of two interference lines at each of the intersections Calculating a straight line perpendicular to the plane, and calculating three-dimensional coordinates of a point separated by a predetermined distance in the linear direction at each of the intersections, and using the obtained point as a teaching point. It is characterized by.

In the method for teaching a painting robot according to the first aspect, when determining the three-dimensional coordinates of the teaching point of the painting robot using the three-dimensional surface data of the object, first, the three-dimensional surface data of the object to be coated is determined. Then, virtual planes in the first direction and a second direction orthogonal to the first direction are caused to interfere with each other, and interference lines in the first direction and the second direction are extracted. The interference lines obtained in this manner have a “go-to-go” shape orthogonal to each other.

Next, after calculating the coordinates of each intersection of the interference lines in the first direction and the second direction, an equation of a plane formed by two orthogonal interference lines at each intersection is calculated. Here, even if the surface of the object to be coated is a surface having a curvature, since it can be microscopically approximated to a plane,
At each intersection, two orthogonal interference lines are regarded as a straight line, and a plane that includes these two interference lines is determined.

When the plane tangent at each intersection is obtained in this way, a straight line perpendicular to this plane is next calculated. Thus, if the paint gun is set on this straight line, the gun angle becomes a right angle with respect to the intersection, so the coordinate system at each intersection is set based on this straight line. Then, the coordinates of a point corresponding to the gun distance in the linear direction are set as teaching points.

As described above, in the method of teaching a painting robot according to the first aspect, the intersection between the first direction and the second direction is calculated, so that an error due to manual operation can be prevented and the painting pitch can be kept constant. can do.
In addition to this, since the plane tangent to each intersection is calculated and its perpendicular is obtained by calculation, the gun angle at each intersection can be set to a right angle with high accuracy, and the teaching point at a predetermined distance on this perpendicular. , The gun distance can be kept constant.

Since such a teaching operation can be performed by a very simple operation, no skill is required as in the prior art, and since there are few teaching errors, there is no need to re-teach, and as a result, the number of teaching steps is significantly reduced.

In the first aspect of the present invention, the first direction and the second direction are not particularly limited, and may be any directions. For example, a teaching method of a painting robot according to claim 2 is characterized in that the first direction is a horizontal direction, and the second direction is a vertical direction, or vice versa.

In the invention according to the second aspect, although not particularly limited, the teaching method of the coating robot according to the third aspect is characterized in that the moving pitch of the vertical virtual plane is a coating pitch. Although not particularly limited in the invention described in claim 1, the teaching method for a painting robot according to claim 4 is characterized in that the predetermined distance in the linear direction at each of the intersections substantially corresponds to a gun distance. And

In the invention according to claims 1 to 4, although not particularly limited, the teaching method of the painting robot according to claim 5 executes each of the above steps by a computer and converts the obtained teaching point data into an actual line. The data is input to a control device of the installed painting robot.

[0022]

According to the first aspect of the invention, since the intersection of the first direction and the second direction is obtained by calculation, the occurrence of an error due to manual operation can be prevented, and the coating pitch can be kept constant. . In addition to this, since the plane tangent to each intersection is calculated and its perpendicular is obtained by calculation, the gun angle at each intersection can be set to a right angle with high accuracy, and the teaching point at a predetermined distance on this perpendicular. , The gun distance can be kept constant. Since such a teaching operation can be performed by a very simple operation, no skill is required as in the prior art, and since there are few teaching errors, there is no need for re-teaching, and as a result, the number of teaching steps is significantly reduced.

According to the second aspect of the present invention, a complicated conversion process with the absolute coordinate system is not required, so that the processing speed can be increased. Further, according to the third and fourth aspects of the present invention, since the teaching data output to the painting robot can be used as it is, the processing time for finding the teaching point is reduced.
According to the fifth aspect of the invention, so-called off-line teaching can be realized, so that the degree of freedom of the teaching operation is further increased.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing an example of a coating robot according to the present invention. The present invention will be described with a robot for a top coating line of an automobile body. FIG. 2 is a side view of the body showing an example of the trajectory of the painting robot according to the present invention. The present invention will be described with an example in which a gun trajectory for painting the side surface of an automobile body is taught.

As shown in FIG. 1, an automobile body B, which is an object to be coated, is continuously transported in a coating booth at a constant speed by a floor conveyor while being mounted on a coating cart D. On both sides in the painting booth, a plurality of painting robots R (here, from the arm to the painting gun G are shown) are arranged at predetermined intervals, and a specific painting operation is assigned to each painting robot R. ing. Although the coating gun G used in the present embodiment is a bell-shaped coating gun, the teaching method of the present invention is not limited to the type of the coating gun G at all, and other types of coating guns may be used. Is also good. Although not shown, the teaching method of the present invention may be applied to a painting robot for painting a horizontal surface of the vehicle body B such as a roof surface, a hood surface, and a trunk surface.

Using the painting robot R equipped with such a bell-shaped painting gun G, the sides of the automobile body B, ie, the front fender FF, the front door FD, and the rear door R
D, when painting the rear fender RF, paint gun G
Can be set, for example, as shown in FIG. In other words, when the vehicle body mounted on the trolley C is transported forward as shown in the figure, the starting point of painting by the painting gun G is set to the front end of the front fender FF and from here to the rear end of the rear fender RF. Paint with a single-stroke trajectory. In the figure, the solid line of the trajectory of the coating gun G indicates ON of the paint, and the dotted line indicates OFF of the paint.

Next, a procedure for teaching the locus of the coating gun will be described. 3 is a flowchart showing an embodiment of the teaching method of the painting robot of the present invention, FIG. 4 is a diagram for explaining step 1 shown in FIG. 3, FIG. 5 is a diagram for explaining step 2 shown in FIG. 6 is a diagram for explaining step 3 shown in FIG. 3, FIG. 7 is a diagram for explaining step 4 shown in FIG. 3, and FIG. 8 is a diagram for explaining steps 5 to 5 shown in FIG.
FIG. 7 is a diagram for explaining No. 7;

The teaching method of the present embodiment is a so-called off-line teaching method, in which a teaching point of a painting robot is determined by using a computer in which CAD (Computer-Aided Design) data of an automobile body B to be coated is stored. The teaching robot performs teaching by inputting the teaching point data to the control device of the actual machine.

First, as shown in FIG.
CAD data 1 (hereinafter, also referred to as surface data) of the side surface of
Is read out, a virtual plane 2 in the horizontal direction is generated on the computer, and this is caused to interfere with the surface data 1 on the side surface of the body. As a result, an interference line H1 between the surface data 1 on the side surface of the body and the virtual plane 2 in the horizontal direction appears. This is extracted (step 1). Since this interference line H1 exists on the virtual plane 2 in the horizontal direction, it becomes a horizontal interference line.

Next, as shown in FIG. 5, the same horizontal virtual plane 2 is moved vertically at arbitrary pitches y1, y2, y3... Hn is extracted (step 2). At this time, since the upper and lower ends of the door panel have a large surface curvature, the pitch y
It is desirable that the gun angle α of the coating gun G is always straight by setting n small and narrowing the interval between the teaching points.

Next, as shown in FIG. 6, a vertical virtual plane 3 is generated on the computer for the same side data 1 on the side of the body, and this is made to interfere with the side data 1 on the side of the body. As a result, an interference line V1 between the surface data 1 on the side surface of the body and the virtual plane 3 in the vertical direction appears. This is extracted (step 3). Since the interference line V1 exists on the virtual plane 3 in the vertical direction, it becomes a vertical interference line.

Then, as shown in FIG. 7, the same vertical virtual plane 3 is moved horizontally at arbitrary pitches x1, x2, x3... Is extracted (step 4). At this time, the pitch xm is desirably the coating pitch P of the coating gun G (see FIG. 9). For a coating portion having no large horizontal curvature such as the side surface of the body, this pitch xm
Is desirably set to be constant.

Thus, the horizontal interference lines H1 to Hn and the vertical interference lines V1 to Vm are extracted. Next, the coordinates of the intersection 4 of these interference lines are calculated by a computer (steps 5 and 5). FIG. 8 (A)). These intersections 4
Are the two-dimensional coordinates of the teaching points of the painting locus of the painting gun G. That is, as shown in FIG. 8B, when the coordinate system on the side surface of the body is the X axis-Y axis, and the direction of the paint gun is the Z axis, the X coordinate and the Y coordinate of the intersection 4 between the two interference lines Hn and Vn. Are the X and Y coordinates of the teaching point.

Next, in Step 6, a plane 5 composed of two interference lines Hn and Vn at each intersection 4 is considered. Here, even if the surface data 1 of the side surface of the body actually has a curvature, it can be considered microscopically at each intersection point 4, so this is regarded as a plane, and its plane equation is calculated by a computer. Ask. For example, in plane data 1 having a curvature as shown in FIG. 8C, when a plane 5 formed near one intersection 4 is obtained, it becomes a plane substantially contacting at the intersection 4. Therefore, the direction Z at which the gun angle α is perpendicular to the plane can be obtained by calculating the perpendicular line at the intersection 4 of the plane 5 with a computer.

Since the perpendicular Z at each intersection 4 is obtained in this way, the vector direction of the three-dimensional coordinate system at each intersection 4 is set in step 7. For example, the perpendicular direction at the intersection 4 obtained in step 6 is set as the Z axis, the front and rear direction of the body is set as the X axis, the height direction of the body is set as the Y axis, and the + direction and the-direction of each axis are set. The setting of this coordinate system is the same at each intersection 4.

Finally, at each intersection point 4, a value corresponding to the gun distance L is input in the direction of the perpendicular Z, and the absolute coordinate system (X, Y, Z) at this time is set as the teaching point of the painting robot. Here, the gun distance L is the same value at each intersection 4, but the actual gun distance L is the distance between the bell cup and the intersection 4, but the teaching point for the painting robot, that is, the painting robot If the reference point of the hand is shifted, enter a value in consideration of the shift.

Once the teaching points (X, Y, Z) at each intersection 4 are set, the order of these teaching points is set along the painting locus as shown in FIG. The data is transferred to the control device of the painting robot installed on the actual line. If a computer having a simulation function is used, it is desirable to perform painting on the computer before transferring the teaching point data to the actual machine, and confirm the operation of the painting robot in advance.

As described above, according to the teaching method of this embodiment, the intersection 4 between the horizontal interference line Hn and the vertical interference line Vn is obtained by calculation using a computer, so that an error caused by manual operation using a touch pen or the like is obtained. Can be suppressed,
The coating pitch P can be kept constant. In addition to this, since the perpendicular line Z is calculated by a computer after calculating the plane 5 which is in contact with each intersection point 4, the gun angle α at each intersection point 4 can be accurately set to a right angle. A teaching point (X,
Since Y, Z) are set, the gun distance L can also be kept constant.

Further, since such a teaching operation can be performed by a very simple operation using a computer, no skill is required as in the prior art, and there are few teaching errors and no need for re-teaching. As a result, the number of teaching steps is significantly reduced. Reduce.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a painting robot according to the present invention.

FIG. 2 is a side view of the body showing an example of a trajectory of the painting robot according to the present invention.

FIG. 3 is a flowchart showing an embodiment of a painting robot teaching method according to the present invention.

FIG. 4 is a diagram for explaining step 1 shown in FIG. 3;

FIG. 5 is a diagram for explaining step 2 shown in FIG. 3;

FIG. 6 is a view for explaining step 3 shown in FIG. 3;

FIG. 7 is a diagram for explaining step 4 shown in FIG. 3;

FIG. 8 is a diagram for explaining steps 5 to 7 shown in FIG. 3;

FIG. 9 is a diagram for explaining a general painting locus, a painting pitch, a gun distance, and a gun angle.

FIG. 10 is a diagram for explaining a situation of occurrence of a coating defect due to a difference in gun angle.

FIG. 11 is a perspective view for explaining a conventional painting robot teaching method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Three-dimensional surface data of a to-be-painted object 2 ... Virtual plane of a horizontal direction (virtual plane of the 1st direction) 3 ... Virtual plane of a vertical direction (virtual plane of a 2nd direction) 4 ... Intersection R ... Coating robots H1-Hn ... interference lines in the horizontal direction V1 to Vn ... interference lines in the vertical direction

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[Procedure amendment]

[Submission date] September 2, 1998

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 10

Claims (5)

[Claims] 1. A coating robot teaching method for determining three-dimensional coordinates of a teaching point of a coating robot using three-dimensional surface data of a coating object, wherein the three-dimensional surface data of the coating object is determined in a first direction. The virtual plane in the first direction is caused to interfere, and the virtual plane in the first direction is moved at an arbitrary pitch in a second direction orthogonal to the first direction. Extracting respective interference lines with a plane; causing the virtual plane in the second direction to interfere with three-dimensional surface data of the object to be coated;
Moving at an arbitrary pitch in the direction, and extracting respective interference lines between the three-dimensional surface data of the object to be coated and the virtual plane in the second direction; and in the first direction extracted in the two steps. Calculating coordinates of each intersection of the interference line and the interference line in the second direction; calculating a plane equation composed of two interference lines at each of the intersections; and calculating a straight line orthogonal to the plane; Calculating a three-dimensional coordinate of a point separated by a predetermined distance in the linear direction at each of the intersections, and using the obtained point as a teaching point. 2. The method according to claim 1, wherein the first direction is a horizontal direction, and the second direction is a horizontal direction.
The method according to claim 1, wherein the direction is a vertical direction. 3. The moving pitch of the virtual plane in the vertical direction is as follows:
3. The method for teaching a painting robot according to claim 2, wherein the painting pitch is a painting pitch. 4. The method according to claim 1, wherein the predetermined distance in the linear direction at each of the intersections substantially corresponds to a gun distance. 5. The method according to claim 1, wherein each of the steps is executed by a computer, and the obtained teaching point data is input to a control device of a painting robot installed on an actual line. How to teach a painting robot.