JP4090620B2 - Automatic welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic welding apparatus applied to TIG welding or the like, and more particularly to a visual sensor type automatic welding apparatus which uses a monitoring camera to input position information of a welded portion and uses it as a control element.
[0002]
[Prior art]
Conventionally, as an automatic welding device applied to, for example, TIG welding, a weld pool being welded is photographed with a monitoring camera, and the electrode tip position, welding wire insertion position, groove shoulder position, and weld pool tip position are based on the image. And the like for revising welding conditions and the like are known. In such a visual sensor type automatic welding apparatus, for example, the left and right electrode aiming positions are controlled based on information on the electrode tip position and the groove shoulder positions, and the electrode tip position and the welding wire insertion position are controlled. Controls the left and right welding wire insertion positions based on the information, and recognizes welding abnormalities based on distance information between the molten pool tip position and the electrode tip position, and corrects welding conditions or cancels welding. 0003
By the way, in photographing the molten pool in TIG welding, the emission intensity of arc light is very high compared to the surroundings. For this reason, the brightness is completely different between the vicinity of the arc light where the electrode tip and the welding wire tip are located, and the groove shoulders and the molten pool contour separated from the arc light, the electrode tip position, the welding wire insertion position, It was extremely difficult to recognize both the groove shoulder positions and the molten pool tip position at the same time.
[0004]
Therefore, conventionally, for example, the welding current is changed to a pulsed current, and the intensity of the arc light is applied to recognize the position of both shoulders of the groove and the position of the molten pool tip during the strong peak current of the arc light. Measures such as recognizing the tip position and welding wire melting position are taken.
[0005]
[Problems to be solved by the invention]
However, in the above-described automatic welding method, the relative luminance on the weld pool or electrode screen is low, and the recognition accuracy of the electrode tip position or the molten pool shape cannot be sufficiently improved.
[0006]
In particular, when correcting or canceling welding conditions, it is difficult to recognize a welding abnormality that does not change the preceding distance of the weld pool, such as a base shape defect, and the quality of the welded part is always sufficiently secured. I can't say that.
[0007]
Also, when controlling the electrode aiming position, if the groove image taken due to the inclination of the installation of the automatic welding head is tilted, the electrode aiming position calculated from the groove shoulder position and the true electrode aiming position The center of a certain groove bottom face shifts and correct electrode aiming position control cannot be performed. When controlling the welding wire aiming position, in the hot wire TIG welding method, if the welding wire insertion position is too close to the arc or the heating amount of the welding wire is too large, the welding wire is quickly melted and burns out.
[0008]
Moreover, when increasing the welding wire supply amount by the hot wire TIG welding method, if the heating amount of the welding wire is too small, a welding defect tends to occur at the bottom of the molten pool regardless of the welding wire insertion position.
[0009]
Furthermore, in order to ensure the images necessary for all controls, a large difference must be made between the peak value and the base value of the pulse current, and the amount of welding wire fed can be reduced by a highly efficient welding method such as hot wire TIG welding. In the case of increasing the construction, it is difficult to secure a high quality because it is impossible to obtain a heat input sufficient for melting the welding wire at the base current.
[0010]
The present invention has been made in view of such circumstances, and an object thereof is to improve the visual recognition accuracy of the electrode tip position and the molten pool shape and simultaneously recognize necessary information from the same image. This makes it possible to perform welding under high current values of both the peak value and base value of the pulse current, and an automatic welding device that can perform high-efficiency welding with an increased supply of welding wire Is to provide.
[0011]
Another object of the present invention is to provide an automatic welding apparatus that can prevent erroneous recognition of the electrode aiming position due to the inclination of the groove, can prevent the welding wire from being burned out, and is also effective in reducing the occurrence of welding defects. It is to provide.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a wavelength-independent neutral density filter having a partially different transmittance distribution, a transmission wavelength in the infrared region, and a peak of arc light are provided in front of the surveillance camera. A filter with a band away from the wavelength is installed so that the molten pool can be photographed. Then, for example, the electrode tip position and both ends of the groove bottom surface are detected from the photographed image to control the left and right electrode aiming positions, and the electrode tip position and the welding wire tip position are detected from the image. In addition, the welding wire aiming position is controlled on the top, bottom, left, and right, and the welding abnormalities are recognized by detecting the shape change of the molten pool front edge and the change of the distance from directly under the arc to the molten pool tip from the captured images. Correct or stop welding. Furthermore, in the hot wire TIG welding method, etc., the shape change of the molten pool front edge is detected from the photographed image, and the output change of the welding wire heating current is added to this, and the upper and lower welding wire target positions and the welding wire heating current are detected. It is characterized by performing control.
[0013]
That is, according to the first aspect of the present invention, the welding head is provided with a monitoring camera, and information such as the electrode tip position, wire tip position, groove position, and molten pool captured by the monitoring camera is input to the control device. An automatic welding apparatus that corrects welding conditions based on a control signal output from the camera, and is installed in front of the monitoring camera, and is partially different so that only the central part of the imaging range by the monitoring camera can be dimmed A neutral density filter having transmittance distribution and a narrow band filter installed in front of the neutral density filter and having a transmission wavelength in the infrared region and a band away from the peak wavelength of the welding light, When controlling torch aiming position based on the video taken by the surveillance camera, the electrode aiming position deviation is judged from both ends of the groove bottom and the electrode tip position, and the left and right electrode aiming positions are controlled. Utotomoni determines welding wire insertion position offset from the electrode tip position and the welding wire melting position, the automatic welding apparatus that controls the welding wire insertion position of the left and right front and rear, the stop of the welding and correcting the welding conditions When performing the welding abnormality from the change in the distance from the electrode tip to the molten pool tip and the shape change of the molten pool leading edge, if it is determined that the shape of the molten pool leading edge is normal, When the distance from the electrode tip to the molten pool tip is measured, and it is determined that this distance is not appropriate, the welding conditions are corrected , and when the shape of the leading edge of the molten pool is determined to be abnormal it determines whether repairable or not a modified welding conditions, performs correction of welding conditions if it is judged to be repaired, if it is determined that the restoration impossible that to perform the stop of the welding Providing automatic welding equipment featuring To.
[0018]
In the invention of claim 2, when correcting the welding conditions in the hot wire TIG welding method and stopping the welding, the welding wire heating current is determined to be insufficient from the shape change of the molten pool leading edge, and the welding wire heating current is controlled. An automatic welding apparatus according to claim 1 is provided.
[0019]
According to the above configuration, by installing a filter whose transmission wavelength is in the infrared region and away from the peak wavelength of the arc light, in front of the camera for photographing the molten pool, The relative luminance increases, and the recognition accuracy of the electrode tip position and the molten pool shape is improved. In particular, by using a neutral density filter having a partially different transmittance distribution and having no wavelength dependency, it is possible to relatively attenuate only the amount of arc light without reducing the surrounding brightness.
[0020]
In addition, since the electrode tip position, welding wire tip position, both end positions of the groove bottom surface, and the weld pool leading edge shape can be recognized from the same image at a time, both the peak value and base value of the pulse current are welded at high current values. It is possible to perform welding with high efficiency by increasing the supply amount of the welding wire.
[0021]
Furthermore, by performing the electrode aiming position control based on the both end positions of the groove bottom face, it is possible to prevent erroneous recognition of the electrode aiming position due to the inclination of the groove.
[0022]
Further, by performing welding wire insertion position control in the up, down, left, and right directions, for example, it is possible to prevent the welding wire from being burned out in the hot wire TIG welding method.
[0023]
Furthermore, in addition to the change in the distance from the electrode tip to the weld pool tip, the weld abnormality can be recognized from the shape change of the weld pool leading edge, so the number of types of weld abnormality that can be recognized can be increased. Generation can be reduced.
[0024]
Moreover, when applied to the hot wire TIG welding method, by controlling the welding wire heating current from the shape change of the molten pool leading edge, it is possible to prevent the occurrence of welding defects due to insufficient heating of the welding wire.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an automatic welding apparatus according to the present invention will be described with reference to the drawings.
[0026]
FIG. 1 shows a system configuration of an automatic welding apparatus according to the present embodiment.
[0027]
As shown in FIG. 1, a welding torch 2, a welding wire feeding tip 3 and a monitoring camera 4 are attached to the welding head 1. FIG. 1 shows the electrode 5 provided at the tip of the welding torch 2 and the welding wire 6 fed from the welding wire feeding tip 3 by performing welding according to preset welding conditions by operating the welding head 1. In this way, the camera 4 (for example, a CCD camera) 4 is used to shoot from an obliquely upper front.
[0028]
In this embodiment, a sensor control device 7, a welding control device 8, and a welding power source 9 are provided. The sensor control device 7 includes the information from the image captured by the monitoring camera 4, the current from the welding power source 9. Based on the voltage output measurement value, the electrode aiming position, the wire aiming position, the modification of the welding conditions and the stop of the welding are determined, and an instruction is sent to the welding control device 8.
[0029]
Further, as shown in an enlarged view in FIG. 2, a neutral density filter (ND filter) 10 and a narrow band filter 11 having no wavelength dependency are installed in front of the monitoring camera 4. The narrow band filter 11 has a transmission wavelength in the infrared region and is set in a band away from the peak wavelength of the arc light 14. Thereby, the relative luminance on the screen of the molten pool and the electrode 5 is increased, and the recognition accuracy of the electrode tip position and the molten pool shape is improved.
[0030]
That is, in the neutral density filter 10 having no wavelength dependency, as shown in FIG. 3, the transmittance of the filter central portion 12 is set low so that the light can be attenuated only in the central portion of the imaging range, and the transmission of the filter outer peripheral portion 13 is performed. The rate is set high.
[0031]
FIG. 4 is an enlarged plan view of a welded portion for explaining a transmission state of the arc light 14. As shown in FIG. 4, in an image photographed by the monitoring camera 4 through the neutral density filter 10 and the narrow band filter 11, the arc light 14 passes through the filter central portion 15 of the neutral density filter 10 having a low transmittance. On the other hand, the amount of light at both ends 18 of the groove bottom recognized by using the reflected light of the arc light 14 passes through the filter outer peripheral portion 13 of the neutral density filter 10 having a high transmittance and is hardly attenuated. Furthermore, the brightness | luminance of an electrode or a molten pool becomes relatively high because the narrow-band filter 11 passes.
[0032]
As a result, the electrode tip 16, the welding wire tip 17, the groove bottom end 18 and the molten pool leading edge shape 19 are clearly projected without being affected by the arc light 14, and each shape and position can be detected on the same screen. It can be done with accuracy. Therefore, it is not necessary to provide a difference between the peak value and the base value of the pulse current, and high-efficiency welding can be performed by increasing the welding wire supply amount.
[0033]
FIG. 5 is a flowchart specifically showing the procedure of welding control in the present embodiment.
[0034]
As shown in FIG. 5, the electrode aiming position is first controlled among all the control items. That is, first, the current electrode aiming position is detected in S1, and whether or not the position is proper is determined in S2. If it is determined that it is not appropriate, the electrode aiming position is corrected in S3, and the corrected result is confirmed again in S1. If it is determined in S2 that the electrode position is appropriate, the wire aiming position is detected in S4, and whether or not it is appropriate is determined in S5. If it is determined that it is not appropriate, the wire aiming position is corrected in S6, and the corrected result is confirmed again in S4.
[0035]
If it is determined in S5 that the wire aiming position is appropriate, the wire heating amount is confirmed in S7. In S8, it is determined whether or not the heating amount is appropriate. If it is determined that the heating amount is not appropriate, the wire heating amount is corrected in S9, and the wire target position in S4 is reconfirmed.
[0036]
In this manner, the welding conditions based on the molten pool leading edge shape are confirmed in S10 under the assumption that the electrode aiming position, the wire aiming position, and the wire heating amount are all appropriate. As a result, if it is determined in S11 that the welding conditions are not appropriate, it is determined in S12 whether or not the welding conditions can be corrected. If correction is possible, the welding conditions are corrected in S13. If possible, the welding is stopped in S14. If it is determined in S11 that the welding conditions are appropriate, the process returns to S1 again, and control proceeds from confirmation of the electrode aiming position.
[0037]
Next, confirmation and control of the electrode aiming position will be described. FIG. 6 is an enlarged plan view showing the welded portion.
[0038]
As shown in FIG. 6, the horizontal distance between the tip 16 of the electrode 5 and the groove bottom end 20 on one side (left side in the figure) with respect to the welding progress direction is L _L , and the electrode tip 16 and the other side (in the figure). If the horizontal distance between the right) groove bottom end 21 and L _R, confirmation of the electrode target position is carried out by measuring these L _L and L _R.
[0039]
FIG. 7 is a flowchart showing a procedure for controlling the electrode aiming position. The 7, and _{L L} and _{L R} is measured in S15, whether a _L L = _{L R} is confirmed in S16. In the case of L _L ≠ L _R is moved and adjusted in the lateral direction with respect to the welding direction position of the welding torch 2 in accordance with the difference between L _L and L _R at S17, the position of the adjustment result is confirmed step S15 . In S16, if it is determined that L L ₌ L _R, confirmation of the electrode target position is completed, it moves to the control of the next wire target position and the wire heating amount.
[0040]
On the other hand, the wire aiming position control is performed based on the information obtained from the molten pool image and the output measurement value obtained from the welding power source 9. FIG. 8 is an enlarged plan view showing the molten pool, and FIG. 9 is a graph showing the time change of the wire heating current obtained from the welding power source 9.
[0041]
As shown in FIG. 8, the information to be confirmed from the weld pool image is the horizontal distance _MY and the vertical distance M _Z1 between the tip 16 of the electrode 5 and the tip 17 of the welding wire 6, and the weld pool tip 23 and the wire tip 17. And the vertical distance _MZ2 . Also, information identifying the welding power source 9, as shown in FIG. 9, the time variation 25 of the wire heating current I _w.
[0042]
Further, the wire heating amount control is also performed based on information obtained from the molten pool image and an output measurement value obtained from the welding power source 9. As shown in FIGS. 10A and 10B, the information to be confirmed from the weld pool image is a shape 26 in the vicinity of the welding wire 6 insertion position at the front edge of the weld pool, and FIG. FIG. 10B shows a state at the time of abnormality. The information to be identified from the welding power source is the time variation 25 of the wire heating current I _w as shown in FIG. 9 described above.
[0043]
FIG. 11 is a flowchart showing a control procedure of the wire aiming position and the wire heating amount.
[0044]
First, in order to control the wire left and right positions, it performed the measurement of M _Y at S18, whether a M _{Y =} 0 is determined in S19. Otherwise M _Y = 0, S20 wire lateral position correction corresponding to the _{M Y} amount is _performed, if _M Y = 0, check the wire left and right positions is completed.
[0045]
Next, in order to check the wire front-rear position, M _Z1 is measured in S21, and it is determined in S22 whether M _Z1 is an appropriate value. If it is not an appropriate value, the wire front / rear position correction is performed in S23 according to the amount of deviation from the appropriate value, and if it is an appropriate value, the confirmation of the wire front / rear position is completed.
[0046]
When the radiant heat of the arc is stronger than normal or when the heating amount of the welding wire 6 is higher than normal (when the heating amount of the wire is excessive), even if _MZ1 is an appropriate value, the welding wire is not inserted before being inserted into the molten pool. since the 6 will be melted, the measurement of the _{I w} is carried out in S24. In S25, I _w is checked whether it is output set value as welding prior to insertion into the molten pool wire 6 melts, when the output of the I _w is decreased (when the wire heating shortage) In step S26, M _Z2 is measured, and it is determined whether M _Z2 = 0.
[0047]
Here, if M _Z2 ≠ 0, it is determined that the radiant heat of the arc is stronger than usual. In S27, the appropriate value of M _Z1 is increased, and the process returns to S21 to correct the wire position away from the arc. If M _{Z2 = 0,} wire heating amount is determined to when more than usual, again is reduced set value of I _w, S21 from the wire longitudinal position correction is performed in S28.
[0048]
In S25, if the I _w is output set value as is, to see if the wire heating amount is not less than normal, the detection of molten pool leading edge shape 26 performed in S29. S30 that during normal molten pool leading edge shape 26 whether (FIG. 10 (A)) is determined, if it is abnormal in shape (FIG. 10 (B)) is a S31 _{I w} The set value is increased, and the front and rear positions of the wire are corrected again from S21. If the molten pool leading edge shape 26 is a normal shape in S30 (FIG. 10A), the confirmation of the wire aiming position and the confirmation of the wire heating amount are completed, and the welding condition confirmation by the molten pool leading edge shape 26 is confirmed. Is done.
[0049]
Regarding confirmation of the welding conditions by the molten pool leading edge shape 26, as shown in FIGS. 12A and 12B, (A) is normal and (B) is abnormal), A wet shape 27 with the groove wall surface is observed. Based on this shape observation, it is possible to prevent the occurrence of welding abnormalities due to disturbances such as substrate shape failure, electrode wear, or gas shield failure. Further, as shown in FIG. 13, the distance L _P from the electrode tip 16 to the molten pool tip 23 is observed, on the basis of this, welding abnormality occurred prevention by welding capacity setting error is made. These control procedures are shown in FIG. In other words, the wet shape 27 of the molten pool leading edge is detected in S32, and it is determined whether or not it is in the normal shape in S33. If the shape is abnormal (FIG. 12B), it is determined in S34 whether or not the repair can be performed by correcting the welding conditions. If so, the welding current is corrected in S35. The result is confirmed in S32. If it is determined that the repair is impossible, the welding is stopped in S36.
[0050]
Further, in S32, if it is determined that the shape of the normal wetting shape 27 of the molten pool leading edge (FIG. 12 (A)), then in S37 the measurement between _{L P} is performed. In S38, it is determined whether or not L _P is an appropriate value. If it is not appropriate, the welding speed is corrected in S39, and the increase or decrease in the welding amount is adjusted. If it is appropriate, the confirmation of all items is completed, and the confirmation is performed again from the electrode aiming position.
[0051]
Further, when the confirmation of the welding conditions at the back wave welding, as shown in FIG. 15, the distance L _P from the electrode tip 16 to the molten pool tip 23 and the molten pool maximum width W _P is measured. In particular, ascending welding is likely to cause back wave dropout. At that time, as shown in the table of FIG. 16 (relationship between the backwave state and the weld pool size in ascending welding), L _P and W _P are normal dimensions. It changes in size. That is, when _LP is large, it is in an unmelted state, and when LP is small, it falls off. Conversely, if the W _P is large becomes fall out, the smaller is the unmelted.
[0052]
Therefore, as shown in the flowchart of FIG. 17, measured between _{L P} and _{W P} is performed in S40, determination of whether the _{L P} and _{W P} is normal value is performed in S41, the result is an abnormal If it is determined, the welding current is corrected in S42, and the result is confirmed in S40. This makes it possible to ensure a good back wave shape.
[0053]
Due to the above welding control, bead shaping failure due to misalignment of the electrode and insufficient melting at the groove, bead shaping failure due to misalignment of the wire aiming position, insufficient weld metal supply due to wire heating failure, generation of voids, poor base shape and electrode High quality compared to conventional products, which can prevent inadequate melting at the groove due to disturbance such as wear and gas shield failure, insufficient melting at the groove due to welding amount setting mistake, and back surface failure due to variations in route dimensions. Can be welded.
[0054]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to improve the visual recognition accuracy of the electrode tip position and the molten pool shape, and simultaneously recognize necessary information from the same image. As a result, it becomes possible to perform welding under a current value in which both the peak value and the base value of the pulse current are high, and high-quality and high-quality welding can be performed with an increased supply amount of welding wire.
[0055]
In addition, according to the present invention, it is possible to prevent erroneous recognition of the electrode aiming position due to the inclination of the groove, to prevent the welding wire from being burned out, and to effectively reduce the occurrence of welding defects.
[0056]
Furthermore, according to the present invention, since the types of welding abnormalities that can be recognized increase, an automatic welding apparatus capable of high-quality welding can be provided.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram showing an automatic welding apparatus according to an embodiment of the present invention.
2 is an enlarged perspective view showing the filter and the like shown in FIG.
3 is a diagram showing a transmittance distribution of the neutral density filter shown in FIG. 2. FIG.
FIG. 4 is a view showing a molten pool image taken by the monitoring camera in the embodiment.
FIG. 5 is a flowchart showing a procedure of welding control.
FIG. 6 is a diagram showing measurement points on a molten pool image when performing electrode aiming position control.
FIG. 7 is a flowchart showing a procedure of electrode aim position control.
FIG. 8 is a diagram showing measurement points on a molten pool image when performing wire aiming position control.
FIG. 9 is a diagram showing a difference in wire heating current output between when the wire heating amount is normal and when heating is excessive.
FIGS. 10A and 10B are diagrams showing the difference in the molten pool leading edge shape between when the wire heating amount is normal and when heating is insufficient.
FIG. 11 is a flowchart showing a procedure for controlling a wire aiming position and a wire heating amount.
FIGS. 12A and 12B are diagrams showing the difference in the weld pool leading edge shape between normal welding and abnormal welding due to disturbance.
FIG. 13 is a diagram showing a distance between an electrode tip and a molten pool tip when performing welding condition control.
FIG. 14 is a flowchart showing a procedure of welding condition control.
FIG. 15 is a diagram showing measurement points on a weld pool image when performing welding condition control in back wave welding.
FIG. 16 is a table showing the relationship between the back wave state and the weld pool size during upward welding.
FIG. 17 is a flowchart showing a welding condition control procedure in reverse wave welding.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Welding head 2 Welding torch 3 Welding wire feeding chip 4 Monitoring camera 5 Electrode 6 Welding wire 7 Sensor control device 8 Welding control device 9 Welding power supply 10 Neutral filter (ND filter)
DESCRIPTION OF SYMBOLS 11 Narrow band filter 14 Arc light 12 Filter center part 13 Filter outer peripheral part 15 Filter center part 16 Electrode tip 17 Welding wire tip 18 Groove bottom end 19 Molten pool leading edge shape 23 Molten pool leading edge 25 Time change 26 Molten pool leading edge shape 27 Wet shape of the molten pool front edge

Claims (2)

The welding head is equipped with a monitoring camera, and information such as the electrode tip position, wire tip position, groove position, and molten pool captured by the monitoring camera is input to the control device, and based on the control signal output from the control device An automatic welding device for correcting welding conditions,
A wavelength-independent neutralizing filter having a partially different transmittance distribution so that only the central part of the photographing range by the surveillance camera can be dimmed, and a front of the darkening filter. It is installed and consists of a narrowband filter whose transmission wavelength is set in the infrared region and a band far from the peak wavelength of welding light, and when performing torch aiming position control based on the image taken by the surveillance camera, From the both ends of the groove bottom surface and the electrode tip position, determine the electrode aim position deviation, control the left and right electrode aim positions, determine the welding wire insertion position deviation from the electrode tip position and the welding wire melting position, In automatic welding equipment that controls the front and rear, left and right welding wire insertion positions,
When correcting the welding conditions and canceling the welding, the welding abnormality is judged from the change in the distance from the electrode tip to the molten pool tip and the shape change of the molten pool leading edge, and the shape of the molten pool leading edge is normal. If it is determined that there is, measure the distance from the tip of the electrode to the tip of the molten pool, and if it is determined that the distance is not appropriate, the welding conditions are corrected and the shape of the leading edge of the molten pool is If it is determined to be abnormal, it is determined whether the repair is possible by correcting the welding conditions. If it is determined that the repair is possible, the welding conditions are corrected . If it is determined that the repair is not possible, An automatic welding apparatus characterized in that welding is stopped. 2. The welding wire heating current is controlled by judging the welding wire heating amount shortage from the shape change of the molten pool leading edge when correcting the welding conditions and stopping the welding in the hot wire TIG welding method. The automatic welding apparatus described.

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