JPS6357149B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a non-contact method for detecting the position and shape of a weld line using an optical distance meter.

In recent years, optical distance meters that use spot light, which are small, lightweight, and easy to handle, have been developed and are now being actively used for position and shape detection.

To give an example, in FIG. 1, a spot light irradiation device 1 is configured to be able to irradiate a light source 2 such as a laser diode or LED as a spot light of a predetermined size using a lens system 3. An angle θ between the optical axis and the optical axis of the light receiving device 4,
The positional relationship between the spot light irradiation device 1 and the light receiving device 4 is already known. The positions of the current planes A and B are determined from the position of the spot light image formed on the lens system 5 of the light receiving device 4 and the light receiving sensor 6 such as a position sensor (a sensor that outputs the position of the center of gravity of the light amount of the spot light image). It is determined by the principles of trigonometry. Distance data obtained by the light receiving device 4 is transferred to the processing device 7 and processed by a microcomputer or the like to detect the position and shape.

When applying the optical distance meter to detect the position and shape of a weld line, the distance detection section 10 of the V-groove section 9 of the welding workpiece 8 in FIG. 2 will be described as follows. There is a problem.

In FIG. 3, a is a V pattern of the distance detection part 10 of the welding work 8, and edge points A, B, C
By detecting the position of the weld line (point B) and the welding conditions, that is, the amount of melted iron (triangle
The area of ABC) can be determined. b is a graph obtained by plotting the distance to the welding workpiece surface in a direction substantially perpendicular to the welding line using a distance meter and connecting the plots. The edge part is rounded and the edge point
The positions of A′, B′, and C′ cannot be detected accurately. This means that the size of the spot light diameter used for detection is 0.5 to 5.
This is due to the fact that it has mm and area. In the processing device 7, straight lines D'A', A'B', B'C', C'E',
Find the equation of A′, B′, from the intersection of the above straight lines.
The position of C can be found.

However, in c, the distance detecting portion 10 has a convex portion F for spatter and dirt, and a concave portion G for a notch. For this reason, it is not possible to accurately determine the edge points A'', B'', and C'' as in the example b above.

The welding work 8 is generally subjected to tack welding, so there are many spatters, etc., and the welding work environment is generally not good, so there is a lot of debris such as flux and rust, and the welding work 8 itself has some notches etc. Detection of weld lines using a rangefinder could only be applied in very limited cases.

The present invention has been made with the above-mentioned points in mind, and it is possible to accurately weld by removing convex obstacles such as spatter and dirt attached to the surface of the welding workpiece, and concave obstacles such as notches. It attempts to detect the position and shape of a line.

That is, using an optical distance meter, the distance to the welding workpiece surface is detected at regular intervals in a direction approximately perpendicular to the welding line (X-axis direction), and the detection operation is performed at regular intervals in the welding line direction (Z-axis direction). A set of detection data obtained by performing the test a certain number of times, and
The average value of a set of detection positions in the axial direction is the same, or the maximum value and/or the minimum value are excluded and the average value of the remaining ones is taken sequentially, and the set of average values is calculated in the X-axis direction. By using the data as shown in FIG. 3, a pattern as shown in b in FIG. 3 can be obtained. In the set of detection data in the X-axis direction at one time, the distance to the welding workpiece surface may not be detected correctly due to the influence of spatter, etc. However, if the position of the welding line in the X-axis direction and welding conditions are the same, A detection position on the X-axis that is affected by the spatter, etc. at a position different from the detection position within a certain pitch in the Z-axis direction that can be considered as a certain pitch is unlikely to be affected by spatter in the same place as above. It's for a reason. The diameter of a single spatter particle is often 1 mm or less, and in normal cases, it hardly affects detection data at two or more different positions in the Z-axis direction.

Specific examples of the present invention will be described below.

Example As part of the copying device of an automatic welding device that performs welding while copying the welding line, welding is carried out in the direction of the welding line (Z-axis direction), that is, in a direction almost perpendicular to the direction of movement of the automatic welding device (X-axis direction). ) is used. In FIG. 4, the optical distance meter 12 attached to the swinging device is used so that m ₁ of the distance detection unit 11 in the Z-axis direction is at an appropriate position with respect to the welding work 8. The distance to the surface of the welding work 8 from x ₁ to x _l (10 to 100 mm) is detected at regular intervals (W _x =0.1 to 5 mm).
m ₂ by advancing the detection operation by W _z ′ (1 to 10 mm) in the Z-axis direction, m ₃ by further advancing W _z ′, and so on, and then repeating the detection operation at a constant pitch in the Z-axis direction (W _z = 5 to 50 mm). Each time, a certain number of times (k = 2 or more times) are performed. The spatter 1 is a set of detection data (l·k pieces) obtained by the above-mentioned detection operation in the processing device 7, and among the set (k pieces) of data with the same detection position in the X-axis direction.
3. By removing the maximum value that is thought to have been affected by dust, etc., and the minimum value that is thought to have been affected by notches, etc., and sequentially taking the average value of the remaining values, Representative data in the axial direction can be obtained, and even when there is an obstacle such as spatter, data close to that shown in FIG. 3b can be obtained, and the position and shape of the weld line can be easily detected. If you use a rangefinder with a small spot light diameter (1 mm or less), you can calculate the equation of a straight line from the average value data obtained by the above process as in the conventional example, and then find the intersection of the straight lines. The position and shape of the weld line can also be detected by performing differentiation and finding the extreme value, without using this method. The particle size of most spatters is 2 mmφ or less, and one spatter rarely affects sensor accuracy at two or more locations, such as m ₁ and m ₂ of the distance detection unit 11 in the Z-axis direction. . The distance information required for detection is
The one in the X-axis direction can be obtained by attaching a pulse encoder or the like to the rotating shaft of the motor of the swinging device, and the one in the Z-axis direction can be obtained by attaching a pulse encoder or the like to the rotating shaft of the cart of the automatic welding device. It is also clear that instead of attaching a distance meter to the swinging device and detecting the distance in the X-axis direction, the same method can be used to detect the distance by controlling a mirror and changing the irradiation position of the spot light in the X-axis direction. be.

Example In FIG. 5, in the case of the above example, the distance data to the welding workpiece surface in the X-axis direction is detected once every fixed pitch (W _z = 1 to 10 mm) in the Z-axis direction, and the above detection operation is performed. The detection operation is carried out three or more times in succession, and the data of the average value obtained by the method of the above embodiment is used as the data in the X-axis direction of the central one of the continuous detection operations. For example, the distance data in the X _- axis direction is detected five times, Z _o-2 , Z _o-1 , Z _o , Z _o+1 , and Z _o+2 at W z = 2 mm pitch, and the detected position in the X-axis direction is The data obtained by excluding the maximum value and sequentially taking the average values of the remaining values is defined as continuous distance data in the X-axis direction at the central position Z _o . By doing this, the detected data can be effectively used many times compared to the above embodiment, and the maximum value of the data can be detected by the comparator using the shift register 14 as shown in FIG. a processing circuit 15 for excluding the remaining data; and a processing circuit 16 for calculating the average value of the remaining data using a counter.
to a predetermined location in the memory (6th
In the case of the figure, the processing speed can be increased by using hardware, such as by inserting the data into the location corresponding to X ₁ of Z _o .

In addition, in the above embodiment, the maximum value and the minimum value of the set of detection data obtained by the detection operation and the detection position in the X-axis direction are the same, and the maximum value We have shown an example in which the average value of the remaining values is taken after excluding the minimum value, but it is also possible to take the average value of the remaining values after excluding only the minimum value, or without excluding the maximum or minimum value at all. However, if the influence of obstacles can be ignored because the number of detections is large when taking the average, it is sufficient to simply take the average value of all data.

As described above, the method for detecting the position and shape of a weld line according to the present invention has the following effects.

(1) Obstacles such as spatter, dirt, and notches can be removed to accurately detect the position and shape of the weld line.

(2) It is easy to implement hardware such as processing equipment to perform high-speed processing.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the schematic configuration of an optical rangefinder.
FIG. 2 is a perspective view showing the distance detection part on the surface of the welding workpiece, FIG. 3 a is a diagram showing the actual groove pattern,
Figure 4 shows a detection pattern in which the position of the weld line can be detected, Figure 4 shows a pattern in which the position of the weld line cannot be detected, and Figure 4 shows a detection pattern in which the position of the weld line can be detected. A perspective view showing the distance detection unit of
FIG. 5 is a diagram showing the correspondence of data according to the present invention, and FIG. 6 is a block diagram of an example of a circuit for calculating an average value for carrying out the method of the present invention. 8... Welding workpiece, 9... Groove section, 10, 11
... Distance detection section, 12 ... Optical distance meter, 13 ...
...Spatter, 14...Shift register, 15,1
6... Processing circuit.

Claims (1)

[Claims] 1 A method of detecting the position and shape of a weld line based on distance information obtained using an optical distance meter, which detects the distance to the welding workpiece surface in a direction approximately perpendicular to the weld line (X-axis direction). is detected at every fixed pitch, and the above-mentioned detection operation is performed a fixed number of times at every fixed pitch in the welding line direction (Z-axis direction), and the detection data obtained by the above-mentioned detection operation is set, and the detection position in the X-axis direction is the same. The average value of the set of data, or the maximum value or the minimum value, or the average value of the remaining data after excluding the maximum and minimum values, is taken one by one, and the set of average values is used as a representative of the set of detected data.
A method for detecting the position and shape of a weld line, characterized by using data in the axial direction.