JP6842171B2 - Automatic welding machine and automatic welding method - Google Patents

Description

The present invention relates to an automatic welding machine and an automatic welding method for welding a joint having two groove edges on which temporary welding has been performed.

If there is a temporary welding bead, welding is affected by the temporary welding bead, so it is not easy to perform welding following the welding line. In this respect, an automatic welding machine for welding a joint having a groove edge to which temporary welding has been performed has been developed (see, for example, Patent Document 1). In this conventional automatic welding machine, two welding line detection sensors are arranged on the left and right along the welding line, for a total of four, and the temporary welding bead is detected to eliminate the influence of the temporary welding bead.

Japanese Unexamined Patent Publication No. 9-234565

The conventional automatic welding machine is provided with a large number of welding line detection sensors (laser type photoelectric sensors), and has a problem that the automatic welding machine becomes expensive. In addition, it is necessary to process signals from a large number of detection sensors, and the signal level from the detection sensors is low in the welding line, the temporary weld bead, and the scratched area, which complicates the copying control process. It ends up. There is also a problem that the reliability of the automatic welding machine becomes low when the copying control process becomes complicated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an automatic welding machine and an automatic welding method in which the copying control process is simplified.

The present inventor has completed the present invention by recalling the use of an imaging device for welding target line detection in order to simplify the copying control process.

The automatic welding machine of the present invention made to solve the problem is supported by a welding robot having a welding torch and the welding robot, and the groove edges of two metal plates are abutted and temporarily welded in a discrete manner. A welding target line is set by processing an imaging unit that captures a groove edge region image ahead of the welded portion of a member to be welded having a temporary weld bead and the groove edge region image captured by the imaging unit. The image processing device includes a robot control unit that controls the welding robot so that the welding torch follows the welding target line set by the image processing device, and the image processing device has a temporary welding bead. A determination unit and a deviation calculation unit for calculating the deviation between the welding target line and the planned welding point to be welded by the welding torch are provided, and the temporary welding bead determination unit is the groove edge region image. A density value determination unit that compares the density value ρ with a predetermined density threshold to determine the presence or absence of the temporary weld bead , along the groove edge in the groove edge region image, or of the temporary weld bead. An edge angle determination unit for determining the presence or absence of the temporary weld bead by comparing the edge angle θ formed by an approximate straight line passing through a plurality of detection segments along the contour line and a reference line with a predetermined edge angle threshold value, and the groove edge. Presence or absence of the temporary welding bead by comparing the standard deviation value σ in the direction intersecting the welding target line at a plurality of detection segment positions along the contour line of the temporary welding bead or along the contour line of the temporary welding bead with a predetermined standard deviation threshold value. The robot control unit is provided with at least one of the standard deviation value determination units for determining, and when the temporary welding bead determination unit determines that there is no temporary welding bead and the deviation calculation unit calculates the deviation, the above. The welding torch is corrected and controlled so that the deviation becomes small, and when the temporary welding bead determination unit determines that the temporary welding bead is present, the correction control is not performed.

The automatic welding method of the present invention, which was made to solve the problem, is an imaging unit supported by a welding robot having a welding torch, and the groove edges of two metal plates are abutted and temporarily welded in a discrete manner. A welding target line is set by processing an imaging step of capturing a groove edge region image ahead of the welded portion of a member to be welded having a temporary weld bead and the groove edge region image captured in the imaging step. The welding target line detection step includes a welding target line setting step and a robot control step of controlling the welding robot so that the welding torch follows the welding target line set in the welding target line setting step. The provisional welding bead determination step of determining the presence or absence of the temporary welding bead and the deviation calculation step of calculating the deviation between the welding target line and the planned welding point to be welded by the welding torch are provided. The weld bead determination step is a density value determination step of comparing the density value ρ of the groove edge region image with a predetermined density threshold to determine the presence or absence of the temporary weld bead, in the groove edge region image. The temporary weld bead is made by comparing the edge angle θ formed by the reference line with the approximate straight line connecting a plurality of detection segments along the groove edge or along the contour line of the temporary weld bead with a predetermined edge angle threshold value. In the edge angle determination step for determining the presence or absence of, the standard deviation value σ in the direction intersecting the welding target line at a plurality of detection segment positions along the groove edge or along the contour line of the temporary welding bead is determined. It is provided with at least one of the standard deviation value determination steps for determining the presence or absence of the temporary weld bead in comparison with the standard deviation threshold, and the robot control step is determined to have no temporary weld bead in the temporary weld bead determination step. When the deviation is calculated in the deviation calculation step, the welding torch is corrected and controlled so that the deviation becomes small, and when it is determined in the temporary welding bead determination step that the temporary welding bead is present, the correction control is performed. It is characterized by not performing.

By processing the groove edge region image captured by the imaging unit, the presence or absence of the temporary welding bead can be reliably determined and the welding torch can be accurately aligned with the welding target line.

It is a schematic block diagram of the automatic welding machine which concerns on Embodiment 1 of this invention. It is a top view view of the member 50 to be welded of FIG. 1, and is the figure explaining the determination of the temporary welding bead. It is a flowchart of the operation of the automatic welding machine which concerns on Embodiment 1. It is a partially enlarged view of the groove edge region image taken by the CCD camera 13. It is a sensing area SE2 which shows typically the state of sensing the boundary of a figure by ordinary image processing. It is a figure which shows typically the sensing area SE1 which image-processed the groove edge area image and erased the groove edge OE52, OE53. It is a figure which shows typically the sensing area SE2 which image-processed the groove edge region image and erased the groove edge OE52, OE53. It is a figure which shows typically the state of determining the presence or absence of a temporary welding bead by the standard deviation value of the detection segment S in the sensing area SE1 which does not have a temporary welding bead. It is a figure which shows typically the state of determining the presence or absence of a temporary welding bead by the standard deviation value of the detection segment S in the sensing area SE2 which has a temporary welding bead. In the sensing area SE1 where there is no temporary welding bead, the presence or absence of the temporary welding bead is schematically shown by the angle formed by the approximate straight line of the detection segment S along the boundary line where the concentration changes and the reference line Lb. It is a figure. In the sensing area SE2 where the temporary welding bead is present, the presence or absence of the temporary welding bead is schematically shown by the angle formed by the approximate straight line of the detection segment S along the boundary line where the concentration changes and the reference line Lb. It is a figure. It is a figure which shows the operation screen of the automatic welding machine which concerns on Embodiment 4. It is a figure which shows the test piece to be welded of the verification experiment 1. As a result of the verification experiment 1, it is a graph which shows the welding line follow-up accuracy when the temporary welding bead determination part is not operated. It is a graph which shows the welding line follow-up accuracy when the temporary welding bead determination part was operated, and the temporary welding area was judged by the density value, the edge angle, and the standard deviation by the result of the verification experiment 1. It is a figure which shows the test piece to be welded of the verification experiment 2. It is a figure which shows the method of the verification experiment 2. It is a screen for inputting the respective thresholds of the density, standard deviation, and edge angle for determining the presence or absence of the temporary welding bead in the verification experiment 2, and displays the current values of the density value ρ, the standard deviation value σ, and the edge angle θ. It is also a screen to do. As a result of the verification experiment 2, it is a graph which shows the welding target line follow-up accuracy when only the density value determination part is operated. As a result of the verification experiment 2, it is a graph which shows the welding line follow-up accuracy when only the standard deviation value determination part is operated. As a result of the verification experiment 2, it is a graph which shows the welding target line follow-up accuracy when only the edge angle determination part is operated. It is a graph which shows the welding target line follow-up accuracy when the density value determination unit or the standard deviation value determination unit is operated by the result of the verification experiment 3. As a result of the verification experiment 4, it is a graph which shows the welding target line follow-up accuracy when the density value determination part or the edge angle determination part is operated. It is a graph which shows the welding target line follow-up accuracy when the standard deviation value determination part or the edge angle determination part is operated by the result of the verification experiment 5. It is a figure which shows the test piece to be welded of the verification experiment 6. It is the result of the verification experiment 6, and is the graph which shows the welding target line follow-up accuracy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
(Embodiment 1)
As shown in FIGS. 1, 2 and 4, the automatic welding machine of the present embodiment is supported by a welding robot 11 having a welding torch 12 and the welding robot 11, and two groove edges OE52 and OE53 are abutted against each other and jump. The image pickup unit 13 that captures the groove edge region image ahead of the welded portion of the member 50 to be welded having the temporary weld bead K1 to K3 temporarily welded to the surface, and the groove edge region image captured by the image pickup unit 13. An image processing device 14 that processes the welding target line WL to set the welding target line WL, and a robot control unit 15 that controls the welding robot 11 so that the welding torch 12 follows the welding target line WL set by the image processing device 14. The processing device 14 includes a temporary welding bead determination unit 141 and a deviation calculation unit 142 that calculates a deviation between the welding target line WL and the planned welding point P to be welded by the welding torch 12. When the temporary welding bead determination unit 141 determines that there is no temporary welding bead and the deviation calculation unit 142 calculates the deviation, the robot control unit 15 corrects and controls the welding torch 12 so that the deviation becomes small. When the temporary welding bead determination unit 141 determines that the temporary welding bead is present, the correction control is not performed. Further, the temporary welding bead determination unit 141 of the present embodiment compares the density value ρ of the groove edge region image imaged by the imaging unit 13 with a predetermined density threshold value to determine the presence or absence of the temporary welding beads K1 to K3. It is provided with a concentration value determination unit D (not shown).

The exact welding target line WL is an intermediate line between the groove edges OE52 and OE53 as shown in FIG. Note that FIG. 4 is enlarged and schematically shown. In reality, the gap between the cross-hatched groove edges OE52 and OE53 is narrow, and the welding target line WL substantially coincides with the groove edges OE52 and OE53. ..

The laser device 16 is connected to the welding torch 12 by an optical waveguide 17. A condenser lens system is incorporated in the welding torch 12. In the case of the arc welding torch 12, for example, the welding torch 12 is connected to the arc welding power supply 16 by an electric wire 17. The image pickup unit 13 is, for example, a CCD camera, and the image processing device 14 includes a CPU.

As shown in FIG. 2, the member 50 to be welded is formed by temporarily attaching and welding two metal plates 52 and 53 to each other at three places. In FIG. 2, K1 to K3 are temporary weld beads, and Wb indicates a weld bead welded by the welding torch 12 of the automatic welding machine according to the present embodiment.

FIG. 4 is a partially enlarged view of the groove edge region image captured by the CCD camera 13, and for convenience of explanation, the surfaces of the metal plates 52 and 53 have high density values (whitish), and thus are shaded at one point. Since the surface of the temporary weld bead K1 has a lower density value (grayish) than the surfaces of the metal plates 52 and 53, it is shaded with a solid line. Since the gap between the groove edge OE 52 of the metal plate 52 and the groove edge OE 53 of the metal plate 53 hardly reflects light, the density becomes low (blackish). Therefore, this gap is cross-hatched with a solid line. In FIG. 4, the rectangular regions SE1 and SE2 are sensing areas, and the image data in the rectangular region is processed. As an example, the outer diameters of the temporary weld beads K1 to K3 are on the order of 3 mm, the sensing areas SE1 and SE2 are on the order of about 3 mm × 3 mm, and the gap between the groove edges OE52 and OE53 is on the order of 0.1 mm. is there. Further, one side intersecting the welding target line WL in the rectangular sensing areas SE1 and SE2 intersects the welding target line WL, and the other side is along the welding target line WL.

As shown in FIG. 4, in the sensing area SE1 without the temporary weld beads K1 to K3, the line connecting the detection segments s1 and s2 along the boundary line (groove edge OE52) where the density changes is the groove edge OE52. Since they are parallel to each other, the line connecting s1 and s2 can be the welding target line WL. However, as shown in FIG. 5, in the sensing area SE2 where the temporary weld bead K1 is located, the detection segments sn and sn + 1 follow the groove edge OE52, but the detection segments sn + 2, sn + 3, sn + 4 ... will follow the contour line of the temporary welding bead K1. Then, the contour line of the temporary welding bead K1 is erroneously detected as the welding target line, and welding is performed so as to follow the erroneously detected welding target line. Therefore, in the automatic welding machine of the present embodiment, the welding target line is not set in the sensing area where the temporary welding bead is located. That is, the automatic welding machine of the present embodiment determines the presence or absence of a temporary welding bead in the sensing area, and if there is a temporary welding bead, controls the welding torch 12 so as to follow a preset welding schedule line. To do. Reference numeral P in FIG. 4 is a planned welding point to be welded by the welding torch 12.

The density value determination unit D of the present embodiment compares the predetermined density threshold value with the average density value ρave of the sensing areas SE1, SE2, ... Of the groove edge region image, and has the presence or absence of the temporary welding beads K1 to K3. Is determined as follows. First, when the distance between the groove edges OE52 and OE53 is narrower than a predetermined value, the image processing device 14 performs image processing so that the groove edges OE52 and OE53 cannot be visually recognized. That is, the image processing device 14 processes so that the wider the distance between the groove edges OE52 and OE53, the darker the display, and the narrower the distance between the groove edges OE52 and OE53, the lighter the display. Then, if the distance between the groove edges OE52 and OE53 is equal to or less than the reference value, the welding target line WL is not displayed. Therefore, the density value determination unit D determines whether or not the temporary welding bead K1 is present by displaying only the temporary welding bead K1 so that the welding target line WL is not displayed by image processing.

FIG. 6 shows a sensing area SE1 in which the density value determination unit D prevents the welding target line WL from being displayed by inputting a predetermined concentration reference value. FIG. 7 shows a sensing area SE2 image-processed so that the welding target line WL is not displayed by inputting a predetermined density reference value by the density value determination unit D. Since the welding target line WL is not displayed in this way, the presence or absence of the temporary welding bead K1 can be reliably determined.

For example, assuming that the white / black density is divided into 256, pure white is 255, and pure black is 0, the surfaces of the metal plates 52 and 53 are close to white and have a large density value ρm, as described above. The surface of the temporary weld bead K1 is close to gray, and the density value ρk is smaller than the density value ρm on the surfaces of the metal plates 52 and 53. That is, ρk <ρm. Therefore, assuming that the average concentration value of the entire sensing area SE2 with the temporary welding bead K1 in FIG. 7 is ρave, ρk ≦ ρave <ρm. Therefore, when the predetermined density threshold values are ρk and ρm (> ρk), the density value determination unit D sets the average density value ρave of the sensing area of the groove edge region image to at least one of ρk ≦ ρave and ρave <ρm. When it is satisfied, it can be determined that there is a temporary welding bead. By doing so, the presence or absence of the temporary welding bead can be stably determined.

As a result of experiments with members to be welded with various groove edges and temporary weld beads, when the white / black density of the groove edge image is divided into 256, white is 255 and black is 0, ρk <20.0. , Ρm> 115.0. Therefore, the density value determination unit D may determine that there is a temporary welding bead when the average density value ρave is 20 ≦ ρave and / or ρave <115.

Next, the operation of the automatic welding machine of the present embodiment will be described with reference to the flowchart of FIG. First, the temporarily welded member 50 to be welded is placed on the table 20, and the welding robot 11 is taught so that the welding torch 12 follows the planned welding line connecting the welding start point Ws and the welding end point We, and welding is performed. Start. When welding starts, the CCD camera 13 acquires a groove edge region image (an image of a region including the groove edges OE52 and OE53) in step 100. Next, in step 110, the image processing device 14 acquires the groove edge OE52 and OE53 (~ welding target line WL) coordinates. Next, in step 120, the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding beads K1 to K3. When it is determined in step 120 that there is no temporary welding bead, the deviation calculation unit 142 is welded with the groove edge OE52, OE53 (~ welding target line WL) coordinate position and the welding torch 12 in step 130. The deviation (difference) from P is calculated and determined. If the difference is determined to be large in step 130, the robot control unit 15 corrects and controls the difference so that the difference becomes small in step 150, and welding is continued in step 160. When it is determined in step 120 that there is a temporary welding bead, the robot control unit 15 stops copying to the welding target line WL in step 140, proceeds to step 160, and welds connecting the welding start point Ws and the welding end point We. Welded to follow the planned line.

(Embodiment 2)
In the automatic welding machine of the present embodiment, the temporary welding bead determination unit 141 of the automatic welding machine of the first embodiment is provided with a standard deviation value determination unit Σ (not shown).

FIG. 8 shows a state of standard deviation value determination in the sensing area SE1. Since there is no temporary weld bead K1 in the sensing area SE1, the detection segments s1, s2, ... Sn are along the boundary line (groove edge OE52) where the density changes. Therefore, the standard deviation value σse1 is small when the x-coordinates (detection segment positions) of the detection segments s1, s2, ... Sn are x1, x2, ... xn.

On the other hand, in the case of the sensing area SE2 shown in FIG. 9, the detection segments sn, sn + 1, and sn + 2 are along the boundary line (groove edge OE52) where the density changes, and the detection segments sn + 3, sn + 4, and sn. +5 is along the boundary line of the temporary weld bead K1. Therefore, when the x-coordinates of each detection segment sn, sn + 1, sn + 2, sn + 3, sn + 4, sn + 5 are xn, xn + 1, xn + 2, ... Xn + 5. The standard deviation value σse2 becomes large, and σse2> σse1.

The standard deviation value determination unit Σ of the present embodiment determines that there is no temporary welding bead when the standard deviation value σ is less than the predetermined standard deviation threshold σl.

As a result of experiments with members to be welded having various groove edges and temporary weld beads, it was found that the presence or absence of temporary weld beads can be accurately determined when σ1 = 50. Therefore, the standard deviation value determination unit Σ of the automatic welding machine in the modified mode determines the presence or absence of the temporary welding bead by setting σ1 = 50.

(Embodiment 3)
In the automatic welding machine of the present embodiment, the temporary welding bead determination unit 141 of the automatic welding machine of the first embodiment is provided with an edge angle determination unit A (not shown).

FIG. 10 shows a state of edge angle determination in the sensing area SE1. Since there is no temporary weld bead K1 in the sensing area SE1, the detection segments s1, s2, s3, and s4 are along the boundary line (groove edge OE52) where the density changes. Therefore, the edge angle θ formed by the approximate straight line SL1 connecting s1 and s4 and the reference line Lb is close to 90 °.

On the other hand, in the case of the sensing area SE2 shown in FIG. 11, the edge angle θ formed by the approximate straight line SL2 connecting the detection segment sn and sn + 1 and the reference line Lb is larger than 90 °. Therefore, in the present embodiment, 90 ° is set as a predetermined edge angle threshold value.

In the present embodiment, the reference line Lb is a line (X-axis) orthogonal to the groove edges OE52 and OE53, but a side parallel to the X-axis of the rectangular sensing area may be used as a reference line.

The edge angle determination unit A of the present embodiment determines that the temporary welding bead is present when θ is larger than 90 °, and determines that the temporary welding bead is not present when θ is 90 °.

When the edge angle θ of the groove edge region image is θs or more and / or θl or less, assuming that the predetermined edge angle thresholds are θs and θl (> θs), the edge angle determination unit A determines that there is no temporary welding bead. It may be determined. By doing so, the presence or absence of the temporary welding bead can be stably determined.

As a result of experiments with members to be welded having various groove edges and temporary weld beads, when θs = 75 ° and θl = 105 °, the edge angle determination unit A can reliably determine the presence or absence of the temporary weld bead. all right. Therefore, the edge angle determination unit A may determine that there is no temporary welding bead when θ is 75 ° or more and / or 105 ° or less.

(Embodiment 4)
In the automatic welding machine of the present embodiment, the temporary welding bead determination unit 141 of the automatic welding machine of the first embodiment includes a concentration value determination unit D, a standard deviation value determination unit Σ, and an edge angle determination unit A. Is.

FIG. 12 shows an operation screen of the automatic welding machine according to the present embodiment. In FIG. 12, since the button surrounded by the dotted line circle is selected, step 140 (when it is determined that the temporary welding bead is present at any one of the density value, the standard deviation value, and the edge angle) (step 140). You can proceed to (see Figure 3). In the example of FIG. 12, since it is determined that there is no temporary welding bead in all of the density value, the standard deviation value, and the edge angle (because there is no display in the temporary attachment determination of the state on the operation screen), step 130 (because there is no display). (See Fig. 3).

In the automatic welding machine of the present embodiment, the temporary welding bead can be identified in various situations by freely combining the density value, standard deviation value, and edge angle with "AND" or [OR], and the welding robot. This leads to stabilization of welding work. For example, if the temporary weld bead is identified by any one of the concentration value, the standard deviation value, and the edge angle, the identification time can be shortened, but the accuracy and reliability cannot be improved. On the other hand, if the temporary weld bead is identified by the density value, the standard deviation value, and the edge angle, the identification time becomes long, but the probability of erroneous identification becomes low, and the accuracy and reliability of the identification become high. Depending on the type of welding work, it may be sufficient to identify the temporary weld bead by one of the density value, standard deviation value, and edge angle, and the density value, standard deviation value, and edge angle may be used. It may be necessary to identify the temporary weld bead. Welding can be performed stably by freely combining the concentration value, standard deviation value, and edge angle with "AND" or [OR] according to the type of welding work.

(Embodiment 5)
The automatic welding method of the present embodiment is a temporary welding bead K1 in which two groove edges OE52 and OE53 are butted and temporarily welded in a discrete manner by a CCD camera 13 supported by a welding robot 11 having a welding torch 12. The welding target, which is an intermediate line between the groove edges OE52 and OE53, is processed by processing the groove edge region image captured in the imaging step P1 and the imaging step P1 to capture the groove edge region image of the member 50 to be welded having ~ K3. Welding includes a welding target line setting step P2 for setting the line WL and a robot control step P3 for controlling the welding robot 11 so that the welding torch 12 follows the welding target line WL set in the welding target line setting step P2. The target line setting step P2 calculates the deviation between the temporary welding bead determination step P4 for determining the presence or absence of the temporary welding beads K1 to K3 and the planned welding point P to be welded by the welding target line WL and the welding torch 12. In the temporary welding bead determination step P4, the density value ρ of the groove edge region image imaged in the imaging step P1 is compared with a predetermined density threshold to compare the temporary welding beads K1 to K3. In the groove edge region image imaged in the density value determination step P41 and the imaging step P1 for determining the presence or absence , along the groove edge OE52 or on the contour line Kn (n = 1, 2, 3) of the temporary welding bead. Edge angle for determining the presence or absence of temporary weld beads K1 to K3 by comparing the edge angle θ formed by the approximate straight line passing through a plurality of detection segments s1, s2, ... Sn along the reference line Lb with a predetermined edge angle threshold value. Judgment step P42, a standard deviation value σ in a direction intersecting the welding target line WL at a plurality of detection segments s1, s2, ... Sn positions along the groove edge OE52 or along the contour line of the temporary welding bead is determined. The robot control step P3 includes at least one of the standard deviation value determination steps P43 for determining the presence / absence of the temporary welding beads K1 to K3 in comparison with the standard deviation threshold of the above. When it is determined that there is no bead and the deviation is calculated in the deviation calculation step P5, the welding torch 12 is corrected and controlled so that the deviation becomes small, and it is determined that the temporary welding bead is present in the temporary welding bead determination step P4. And, the correction control is not performed.

The automatic welding method of the deformation mode controls the welding torch 12 so as to follow a preset welding schedule line when the robot control step P3 does not perform the correction control. In another modification of the automatic welding method, when the robot control step P3 does not perform the correction control, the welding torch 12 is controlled so as to follow the extension line of the immediately preceding welding target line WL.

(Verification experiment 1)
Followability of the welding torch to the welding target line WL when the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding bead based on the density value ρ, the standard deviation value σ, and the edge angle θ without emitting a laser beam. I examined. That is, the accuracy of following the welding target line WL was compared between the case where the determination function of the temporary weld bead was exerted and the case where the temporary welding bead determination function was not exerted by using the butt joint material of the SPCC steel plate having a plate thickness of 2.6 mm.

The test piece is shown in FIG. Two SPCC steel plates having a plate thickness of 2.6 mm, a length of 410 mm, and a width of 30 mm were used as butt joints, and a welding torch was run from the welding start point Ws of the test piece to the welding end point We. Temporary welding beads K1, K2, and K3 are laser spot welded and have a circular shape with a diameter of 3.2 mm. In this verification experiment, the groove gap was set to 0 with a butt joint having no groove. The welding robot was taught so that the planned welding line was intentionally shifted from the welding target line WL so that the amount of removal of the nerai was 0 mm at the welding start point Ws and the amount of removal of the nerai was 2 mm at the welding end point We. ..

FIG. 14 shows a change in the amount of deviation of the welding torch 12 from the welding target line WL when the temporary welding bead determination unit 141 is not operated. A maximum deviation of 0.7 mm has occurred.

FIG. 15 shows a change in the amount of deviation of the welding torch 12 from the welding target line WL when the temporary welding bead determination unit 141 is operated. From this, it can be seen that the maximum value of the deviation amount of the welding torch 12 from the welding target line WL when the temporary welding bead determination unit 141 is operated is 0.095 mm. This amount of deviation does not pose a problem in ensuring good welding quality in performing laser welding.

(Verification experiment 2)
When laser welding is performed and the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding bead by any of the density value ρ, the standard deviation value σ, and the edge angle θ, the welding bead is applied to the welding target line WL. The followability was examined. That is, using the butt joint material of the SPCC steel plate having a plate thickness of 1.2 mm, the temporary weld bead determination unit 141 uses any one of the concentration value ρ, the standard deviation value σ, and the edge angle θ. The accuracy of following the welding target line WL of the welding torch was investigated when the presence or absence of the welding torch was determined.

The test piece is shown in FIG. Two SPCC steel plates having a plate thickness of 1.2 mm, a length of 320 mm, and a width of 30 mm were used as butt joints and temporarily welded at three locations at a pitch of 100 mm. In this experiment, the groove gap was set to 0 with a butt joint having no groove.

The laser power is 2KW and the welding speed is 3m / min. For the welding robot, intentionally shift the planned welding line from the welding target line WL so that the amount of removal of the nerai is 0 mm at the welding start point Ws and the amount of removal of the nerai is 1.5 mm at the welding end point We. Welded. After welding, the position of the welding target line WL and the center position of the welding bead after welding were measured using a microscope to evaluate the copying accuracy. After welding with a total welding length of 300 mm at 7 locations with a length of 30 mm at a pitch of 40 mm, the deviation δ between the position of the welding target line WL and the center position of the weld bead after welding was measured (see FIG. 17). ..

In order to determine the presence or absence of the temporary weld bead, the threshold values of the concentration value ρ, the standard deviation value σ, and the edge angle θ were input. The input screen is shown in FIG. When the density value ρ is the density threshold value of 20 or more and 115 or less, it is determined that the temporary welding bead is present. When the standard deviation value σ is 50 or more of the standard deviation threshold value, it is determined that the temporary welding bead is present. When the edge angle θ is the edge angle threshold value of 75 ° or more and 105 ° or less, it is determined that there is no temporary welding bead. That is, when the edge angle θ is less than 75 ° and exceeds 105 °, it is determined that the temporary welding bead is present.

FIG. 19 shows the amount of deviation of the welding bead from the welding target line WL when the presence or absence of the temporary welding bead is determined by the concentration value ρ alone. The average amount of deviation is 0.083 mm, and there is a maximum of +0.120 mm and a minimum of 0.02 mm of copying deviation with respect to the coordinate position of the welding target line WL. The maximum copying deviation is +0.120 mm, and the copying accuracy of ± 0.15 mm is satisfied, which enables good welding by laser welding even when only the concentration value is judged.

FIG. 20 shows the amount of deviation of the welding bead from the welding target line WL when the presence or absence of the temporary welding bead is determined by the standard deviation value σ alone. The average amount of deviation is 0.087 mm, and there is a maximum of +0.130 mm and a minimum of 0.05 mm of copying deviation with respect to the coordinate position of the welding target line WL. Even if only the standard deviation value is judged, the copying accuracy of ± 0.15 mm, which enables good welding by laser welding, is satisfied.

FIG. 21 shows the amount of deviation of the welding bead from the welding target line WL when the presence or absence of the temporary welding bead is determined by the edge angle θ alone. The average amount of deviation is 0.080 mm, and there is a maximum of +0.11 mm and a minimum of 0.05 mm of copying deviation with respect to the coordinate position of the welding target line WL. Even if only the edge angle is judged, the copying accuracy of ± 0.15 mm, which enables good welding by laser welding, is satisfied.

(Verification experiment 3)
When the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding bead by "OR" of the concentration value ρ and the standard deviation value σ, the followability of the weld bead to the welding target line WL is investigated. .. Since the test piece, experimental conditions, etc. are the same as those in the verification experiment 2, the description thereof will be omitted.

FIG. 22 shows the experimental results. The average amount of deviation is 0.052 mm, and there is a maximum of +0.130 mm and a minimum of 0.06 mm of copying deviation with respect to the coordinate position of the welding target line WL. Even when the concentration value ρ and the standard deviation value σ are combined by "OR", the copying accuracy of ± 0.15 mm is satisfied, which enables good welding by laser welding without being affected by the disturbance caused by the temporary welding bead. ..

(Verification experiment 4)
When the temporary welding bead determination unit 141 determined the presence or absence of the temporary welding bead by "OR" of the concentration value ρ and the edge angle θ, the followability of the welding bead to the welding target line WL was examined. Since the test piece, experimental conditions, etc. are the same as those in the verification experiment 2, the description thereof will be omitted.

FIG. 23 shows the experimental results. The average amount of deviation is 0.088 mm, and there is a maximum of +0.140 mm and a minimum of 0.04 mm of copying deviation with respect to the coordinate position of the welding target line WL. Even when the concentration value ρ and the edge angle θ are combined by “OR”, the copying accuracy of ± 0.15 mm is satisfied, which enables good welding by laser welding without being affected by the disturbance caused by the temporary welding bead.

(Verification experiment 5)
When the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding bead at the “OR” of the standard deviation value σ and the edge angle θ, the followability of the weld bead to the welding target line WL is investigated. ..

FIG. 24 shows the experimental results. The average amount of deviation is 0.083 mm, and there is a maximum of +0.120 mm and a minimum of 0.05 mm of copying deviation with respect to the coordinate position of the welding target line WL. Even when the standard deviation value σ and the edge angle θ are combined by “OR”, the copying accuracy of ± 0.15 mm is satisfied, which enables good welding by laser welding without being affected by the disturbance caused by the temporary welding bead. ..

(Verification experiment 6)
The followability of the weld bead to the welding target line WL when the temporary weld bead determination unit 141 determines the presence or absence of the temporary weld bead based on the concentration value ρ, the standard deviation value σ, and the edge angle θ was investigated.

The test piece is shown in FIG. Two SPCC steel plates having a plate thickness of 1.2 mm, a length of 610 mm, and a width of 30 mm were used as butt joints and temporarily welded at four locations at a pitch of 150 mm. In this experiment, the groove gap was set to 0 with a butt joint having no groove.

The laser power is 2KW and the welding speed is 3m / min. The welding robot was taught so as to intentionally shift the welding target line WL so that the amount of removal of the nerai was 0 mm at the welding start point Ws and the amount of removal of the nerai was 2 mm at the welding end point We. After welding, the position of the welding target line WL and the center position of the welding bead after welding were measured using a microscope to evaluate the copying accuracy. After welding with a total welding length of 600 mm at 15 locations with a length of 30 mm at a pitch of 40 mm, the deviation δ between the position of the welding target line WL and the center position of the weld bead after welding was measured (see FIG. 17). ..

In order to determine the presence or absence of the temporary weld bead, the threshold values of the concentration value ρ, the standard deviation value σ, and the edge angle θ were input (see FIG. 18). When the density value ρ is the density threshold value of 20 or more and the concentration threshold value of 115 or less, it is determined that the temporary welding bead is present. When the standard deviation value σ is 50 or more of the standard deviation threshold value, it is determined that the temporary welding bead is present. When the edge angle θ is equal to or greater than the edge angle threshold value of 75 ° and equal to or less than the edge angle threshold value of 105 °, it is determined that there is no temporary welding bead. That is, when the edge angle θ is less than 75 ° and exceeds 105 °, it is determined that the temporary welding bead is present.

When the temporary welding bead determination unit 141 determines the presence or absence of the temporary welding bead by combining the density value ρ, the standard deviation value σ, and the edge angle θ with “OR”, the welding bead is applied to the welding target line WL. The followability was investigated.

FIG. 26 shows the experimental results. The average amount of deviation is 0.050 mm, and a maximum of +0.140 mm and a minimum of -0.035 mm are copied with respect to the coordinate position of the welding target line WL. It satisfies the copying accuracy of ± 0.15 mm, which enables good welding by laser welding without being affected by the disturbance caused by the temporary welding bead.

Welding speed is set to 1 m / min (laser power: 1.2 kW), 5 m / min (laser power: 3 kW), 7 m / min (laser power: 3.5 kW), 10 m / min (laser power: 5 kW), and the same. Experiment was conducted.

The average amount of deviation at each welding speed is 0.041 mm at a welding speed of 1 m / min, 0.062 mm at a welding speed of 5 m / min, 0.082 mm at a welding speed of 7 m / min, and 0.045 mm at a welding speed of 10 m / min. Met. It was found that under all welding conditions, the copying accuracy of ± 0.15 mm, which enables good welding by laser welding, was satisfied.

The present invention is not limited to such embodiments and verification experiments, and square joints other than butt joints, lap joints, fillet joints, lap fillet joints, T joints, flare joints, edge joints, etc. Applicable to. The present invention can also be applied to overlaying and brazing other than welding.

11 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Welding robot 12 ・ ・ ・ ・ ・ ・ ・ ・ Welding torch 13 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Imaging unit 14 ・ ・ ・ ・ ・ ・ ・ ・Image processing device 141 ・ ・ ・ ・ ・ ・ ・ ・ Temporary welding bead judgment unit 142 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・·················································································································・ ・ ・ Edge angle determination unit K1 to K4 ・ ・ ・ ・ ・ ・ ・ Temporary welding beads OE52, OE53 ・ ・ ・ Groove edge s1, s2, ・ ・ sn ・ ・ ・ ・ Detection segment ρ ・ ・ ・ ・ ・・ ・ ・ Density value θ ・ ・ ・ ・ ・ ・ ・ ・ Edge angle σ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Standard deviation value

Claims (6)

A welding robot having a welding torch and a portion to be welded of a member to be welded having a temporary welding bead that is supported by the welding robot and has a temporary welding bead in which the groove edges of two metal plates are butted and temporarily welded. An imaging unit that captures a groove edge region image, an image processing device that processes the groove edge region image captured by the imaging unit to set a welding target line, and the welding target set by the image processing device. It has a robot control unit that controls the welding robot so that the welding torch follows the line.
The image processing device includes a temporary welding bead determination unit and a deviation calculation unit that calculates a deviation between the welding target line and a planned welding point to be welded by the welding torch.
The temporary weld bead determination unit compares the density value ρ of the groove edge region image with a predetermined density threshold to determine the presence or absence of the temporary weld bead, and the temporary weld bead determination unit of the groove edge region image. The temporary attachment is performed by comparing the edge angle θ formed by the reference line and the approximate straight line passing through a plurality of detection segments along the groove edge or along the contour line of the temporary welding bead with a predetermined edge angle threshold value. An edge angle determination unit that determines the presence or absence of a weld bead, and a standard deviation value σ in a direction that intersects the weld target line at a plurality of detection segment positions along the groove edge or along the contour line of the temporary weld bead. It is provided with at least one of the standard deviation value determination units for determining the presence or absence of the temporary weld bead in comparison with a predetermined standard deviation threshold value.
When the temporary welding bead determination unit determines that there is no temporary welding bead and the deviation calculation unit calculates the deviation, the robot control unit corrects and controls the welding torch so that the deviation becomes small. An automatic welding machine characterized in that the correction control is not performed when the temporary welding bead determination unit determines that the temporary welding bead is present. Assuming that the predetermined density thresholds are ρk and ρm (> ρk), the density value determination unit temporarily determines that the density value ρ of the groove edge region image satisfies at least one of ρk ≦ ρ and ρ <ρm. The automatic welding machine according to claim 1, wherein it is determined that there is a welding bead attached. The claim that the edge angle determination unit determines that there is no temporary welding bead when the edge angle θ is θs or more and / or θl or less, assuming that the predetermined edge angle thresholds are θs and θl (> θs). The automatic welding machine according to 1 or 2. An imaging unit supported by a welding robot with a welding torch, ahead of the welded part of a member to be welded with a temporary welding bead in which the groove edges of two metal plates are butted and temporarily welded. Welding edge region image imaging process and
A welding target line setting step of processing the groove edge region image captured in the imaging step to set a welding target line, and a welding target line setting step.
A robot control step of controlling the welding robot so that the welding torch follows the welding target line set in the welding target line setting step is provided.
The welding target line setting step is a deviation calculation for calculating the deviation between the temporary welding bead determination step for determining the presence or absence of the temporary welding bead and the planned welding point to be welded by the welding torch. With the process,
The temporary welding bead determination step is a density value determination step of comparing the density value ρ of the groove edge region image with a predetermined density threshold value to determine the presence or absence of the temporary weld bead, and the groove edge region image. The temporary attachment is performed by comparing the edge angle θ formed by the reference line and the approximate straight line passing through a plurality of detection segments along the groove edge or along the contour line of the temporary welding bead with a predetermined edge angle threshold value. An edge angle determination step for determining the presence or absence of a weld bead, a standard deviation value σ in a direction intersecting the weld target line at a plurality of detection segment positions along the groove edge or along the contour line of the temporary weld bead. It includes at least one of the standard deviation value determination steps for determining the presence or absence of the temporary weld bead in comparison with a predetermined standard deviation threshold.
In the robot control step, when it is determined in the temporary welding bead determination step that there is no temporary welding bead and the deviation is calculated in the deviation calculation step, the welding torch is corrected and controlled so that the deviation becomes small. An automatic welding method characterized in that the correction control is not performed when it is determined in the temporary welding bead determination step that the temporary welding bead is present. The automatic welding method according to claim 4, wherein the robot control step controls the welding robot so that the welding torch follows a preset welding schedule line when the correction control is not performed. The automatic welding method according to claim 4, wherein the robot control step controls the welding robot so that the welding torch follows an extension of the immediately preceding welding target line when the correction control is not performed.

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