JP4854860B2 - Welding line scanning determination device and scanning control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  In the butt welding method in which the groove width is narrower than the oscillating width, the present invention is based on the welding current waveform when the welding torch is oscillated in the groove width direction. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning determination device that determines a scanning state of a weld line in arc sensing control that is to be copied, and a scanning control device that uses this determination technology.
[Prior art]
  In consumable electrode arc welding in recent years, arc sensing control is generally used as a method for controlling the welding torch along the weld line of a welding base material.
[0002]
  This arc sensing control is based on the change in welding current caused by the change in the consumable electrode (welding wire) protrusion length when the welding torch is oscillated in the groove width direction of the weld base metal. (Hereinafter referred to as the oscillating direction) and the groove vertical direction (hereinafter referred to as the torch axis direction) are corrected and controlled.
[0003]
  However, since the arc phenomenon is extremely unstable and progresses at an ultra-high speed, the current arc sensing control reliability is low, especially in fields that require high-precision welding quality such as high-speed welding of thin plates. There is a strong demand for improved performance. For this reason, various methods for improving the reliability of arc sensing control have been proposed in the past, but the reality is that satisfactory methods have not yet been obtained at a practical level.
[0004]
  Therefore, the present applicant completely removes the welding current waveform in the short-circuit period, which is a disturbance factor of the arc sensing control, and performs an equalizing process and a half-cycle inversion polymerization process on the welding current waveform obtained by linearly interpolating the removal period. A revolutionary method for calculating the oscillation direction deviation and the torch axis direction deviation, and based on this method, a welding line copying determination device by arc sensing control that corrects the torch position in the oscillation direction and the torch axis direction, and A scanning control device is proposed in Japanese Patent Application No. 11-230881.
[Problems to be solved by the invention]
  The arc sensing control of this Japanese Patent Application No. 11-230881 is not easily affected by short circuit or spatter that acts as a disturbance factor on the welding current value, and can cope with a high welding speed by a high-speed oscillating frequency. The reliability of arc sensing control has been greatly improved.
[0005]
  However, in the arc sensing control described above, the oscillating direction of the groove position is difficult to detect in the case of butt welding where the groove width of the weld base metal is narrower than the oscillation amplitude range, the arc sensing control is not performed as it is. It was found that it was not applicable.
[0006]
  The object of the present invention is not easily affected by short circuit or spatter that acts as a disturbance factor on the welding current value, and can cope with an increase in welding speed due to a high-speed oscillation frequency. An object of the present invention is to provide a welding line scanning determination device and a scanning control device that are applicable to butt welding or the like having a narrow groove width and that are highly reliable in arc sensing control.
[Means for Solving the Problems]
  In order to solve the above-mentioned problem, the invention according to claim 1
(A) Current detection means for detecting a welding current waveform when the welding torch is oscillated in a direction perpendicular to the welding line in butt welding of consumable electrode type arc welding in which short-circuiting and arc are repeatedly welded;
(B) a short-circuit waveform removing unit that removes a short-circuit waveform that is a welding current waveform in a short-circuit period from the welding current waveform detected by the current detection unit;
(C) linear interpolation means for interpolating a waveform missing portion of the welding current waveform from which the short-circuit waveform has been removed, with a straight line;
(D) The welding current waveform subjected to the linear interpolationBy moving averageLeveling means to level the smooth waveform,
(E) differential conversion means for converting the smooth waveform into a differential waveform;
(F) cutting means for cutting the differential waveform into a plurality of sections corresponding to the oscillation period of the welding torch;
(G) a polymerization means for polymerizing the differential waveforms cut by the cutting means in a mutually inverted state every half cycle;
(H) of the differential waveform found by the superposition means.Each near the quarter and three quarter cyclesOscillation direction deviation display means for displaying the deviation direction and deviation amount of the center position of the weld line with respect to the oscillation width direction of the welding torch, with the intersection of the waveforms as the groove center position, is provided.
[0007]
  According to the invention, the waveform of the welding current detected by the current detection means is linearly interpolated by the linear interpolation means after the short-circuit waveform is removed by the short-circuit waveform removal means, and the waveform interpolation is performed. Then, the smoothing process is performed, and then converted into a differential waveform by the differential conversion means.
[0008]
  Further, this differential waveform is cut into a plurality of sections corresponding to the oscillating period of the welding torch by the cutting means, and is subjected to reverse polymerization processing every half period, thereby finding the quarter and quarter. Corresponding to the intersection of the maximum and minimum values of the differential waveform near the three cycles, the deviation direction and deviation amount of the center position of the weld line with respect to the oscillation width direction of the welding torch are displayed by the oscillation direction deviation display means. Is done.
[0009]
  In the case of butt welding in which the groove width of the weld base metal is narrower than the oscillation amplitude range, according to the technique of the aforementioned Japanese Patent Application No. 11-230881, as shown in FIG. The welding current waveform Y (curve in FIG. 8 (A)) is an approximate straight line L (in FIG. 8 (B)) by the least square method of a curve (curve in FIG. 8 (B)) folded and overlapped every half cycle. The inclination angle of the horizontal line) was very small due to the flatness of the surface of the welded material on the left and right sides of the groove portion, and the position of the weld line in the oscillating width direction could not be determined.
[0010]
  However, according to the present invention, since the differential waveform of the welding current is used, as shown in FIG. 8C, even if the same welding current waveform after linear interpolation and leveling processing is used, Since the groove inclination angle changes greatly with the lower end of the V-groove as a boundary, the change in the differential value of the welding current differential waveform is large, thereby making it possible to determine the position of the weld line.
[0011]
According to the above invention, by appropriately setting the forward sampling time and the sampling number for each moving averageWith welding progressAlmost real timeSlipA simple welding current waveform can be obtained..
[0012]
  Claim2In the invention described in the above, the short-circuit waveform removing means includes:
  Threshold setting means for setting, as a threshold, a reference voltage for distinguishing between the arc period and the short circuit period in the welding voltage waveform;
  First calculation means for calculating a position of a welding current waveform corresponding to a time point a predetermined time before the arrival point at which the reference voltage is reached in the welding voltage waveform as a short-circuit waveform removal start point;
  Second calculation means for calculating a position of a welding current waveform corresponding to a time point after a predetermined time from an escape point escaped from the reference voltage in the welding voltage waveform as a short-circuit waveform removal end point;
  Waveform erasing means for erasing the current waveform between the short-circuit waveform removal start point and the short-circuit waveform removal end point based on the calculation results of the first calculation means and the second calculation means is provided. .
  Although it is very difficult to clearly specify the start point and the end point of the short-circuit waveform, according to the invention, the reference voltage for temporarily distinguishing the arc period and the short-circuit period of the welding current by the threshold setting means is a threshold value. Based on this threshold value, the first calculation means and the second calculation means expand the waveform portion to be erased as a disturbance factor by a predetermined width before and after the temporary short-circuit period determined by the threshold value. Therefore, the influence of a short circuit, which is a large disturbance factor in determining the copying of the welding torch, is completely eliminated.
[0013]
  Claim3The invention described inOutput from the robot torch position controller to the welding robot system to reversely move the welding torch at the oscillation end point.Oscillator sync pulse signalWhen outputWhen,Actual welding torch acylate end pointWhen it arrivesBetweentime lagIs detected in advance and thistime lagOnly minutesSaidThe cutting timing of the welding current waveform by the cutting means is set with a delay from the oscillation synchronizing pulse signal.
[0014]
  According to the invention, the cutting timing of the welding current by the cutting means is oscillating.SyncPulse signalWhen outputtingAnd actual welding tochiosylate end pointWhen it arrivesoftime lagTherefore, the accuracy and reliability of the welding line copying determination device are improved.
  And claims4The invention described in
(A) In butt welding of consumable electrode type arc welding in which short-circuit and arc are repeatedly welded, current detection means for detecting a welding current waveform when the welding torch is oscillated in a direction perpendicular to the welding line;
(B) a short-circuit waveform removing unit that removes a short-circuit waveform that is a welding current waveform in a short-circuit period from the welding current waveform detected by the current detection unit;
(C) linear interpolation means for interpolating a waveform missing portion of the welding current waveform from which the short-circuit waveform has been removed, with a straight line;
(D) The welding current waveform subjected to the linear interpolationBy moving averageLeveling means to level the smooth waveform,
(E) differential conversion means for converting the smooth waveform into a differential waveform;
(F) cutting means for cutting the differential waveform into a plurality of sections corresponding to the oscillation period of the welding torch;
(G) a polymerization means for polymerizing the differential waveforms cut by the cutting means in a mutually inverted state every half cycle;
(H) of the differential waveform found by the superposition means.Each near the quarter and three quarter cyclesAn oscillating direction deviation calculating means for calculating the deviation direction and the deviation amount of the welding line center position with respect to the oscillation width direction of the welding torch, with the intersection of the waveforms as the groove center position,
(I) comparing a welding current value corresponding to a differential value zero of the differential waveform with a set current value, and calculating a deviation direction and a deviation amount of the welding torch in the torch axial direction; And (J) based on the calculation results of the oscillating direction deviation calculating means and the torch axial direction deviation calculating means, the oscillation center of the welding torch in a direction to eliminate the oscillating direction deviation and the torch axial direction deviation. Torch heightTheIt is characterized by feedback control.
[0015]
  According to the invention, in addition to the function of the copying determination device according to claim 1, since the oscillation direction deviation calculating means and the torch axial direction deviation calculating means are provided, the calculation is performed by both means. Since the oscillation center position of the welding torch and the welding torch height are feedback-controlled based on the shift data, it is possible to control the welding line tracing with high accuracy and reliability.
[0016]
  According to the above invention, by appropriately setting the forward sampling time and the sampling number for each moving averageWith welding progressAlmost real timeSlipA simple welding current waveform can be obtained.
[0017]
  Claim5In the invention described in the above, the short-circuit waveform removing means includes:
  Threshold setting means for setting, as a threshold, a reference voltage for distinguishing between the arc period and the short circuit period in the welding voltage waveform;
  First calculation means for calculating a position of a welding current waveform corresponding to a time point a predetermined time before the arrival point at which the reference voltage is reached in the welding voltage waveform as a short-circuit waveform removal start point;
  Second calculation means for calculating a position of a welding current waveform corresponding to a time point after a predetermined time from an escape point escaped from the reference voltage in the welding voltage waveform as a short-circuit waveform removal end point;
  Waveform erasing means for erasing the current waveform between the short-circuit waveform removal start point and the short-circuit waveform removal end point based on the calculation results of the first calculation means and the second calculation means is provided. .
[0018]
  According to the above invention, since the influence of a short circuit, which is a large disturbance factor in determining the copying of the welding torch, is completely removed, the accuracy and reliability of the welding line copying control is improved..
[0019]
  Claim6The invention described inOutput from the robot torch position controller to the welding robot system to reversely move the welding torch at the oscillation end point.Oscillator sync pulse signalWhen outputWhen,Actual welding torch acylate end pointWhen it arrivesBetweentime lagIs detected in advance and thistime lagOnly minutesSaidThe cutting timing of the welding current waveform by the cutting means is set with a delay from the oscillation synchronizing pulse signal.
[0020]
  According to the invention, the cutting timing of the welding current by the cutting means is oscillating.SyncPulse signalWhen outputtingAnd actual welding tochiosylate end pointWhen it arrivesoftime lagTherefore, the accuracy and reliability of the welding line copying determination device are improved.
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0021]
  FIG. 1 is a block diagram showing an outline of a copying control apparatus including a welding line copying determining apparatus according to an embodiment of the present invention. When there is no feedback from the oscillating direction deviation calculating means 17 and the torch axial direction deviation calculating means 19 to the robot torch position control device 21, it becomes a simple copying determination device.
[0022]
  In FIG. 1, 1 is a consumable electrode type gas shielded arc welding apparatus (hereinafter simply referred to as an arc welding apparatus) including a welding robot 1a, 2 is a welding power source apparatus, 3 is a base material having a butt weld, and 4 is a welding electrode. It is a welding wire.
[0023]
  The supply side 7 of the welding wire 4 is wound in a coil shape, and the tip of the welding wire 4 fed out from the coil-like supply side 7 through the feeding roller 6 at a predetermined speed is a contact of the welding torch 5. It is fed in the direction of the base material 3 while being held by the chip 5a.
[0024]
  Further, 10 is a welding current detection means, and 11 is a welding voltage detection means. The detection means 10 and 11 detect the welding current and the welding voltage supplied from the welding power source device 2 to the base material 3 and the welding wire 4, respectively. It has become so.
[0025]
  12 is a short-circuit waveform removing means, 13 is a linear interpolation means, 14 is a differential conversion means, 15 is a clipping means, 16 is a folding superposition means, 18 is an oscillating direction deviation display means, 17 is an oscillating direction deviation calculating means, and 20 is Torch axial direction shift display means, 19 is a torch axial direction shift calculating means, 21 is a robot torch position control device, and 22 is an oscillating direction end point detecting means. Hereinafter, each block shown in FIG. 1 will be further described.
[0026]
  The welding power source device 2 is a high-speed control type that performs output control by an inverter method, and can control the waveform of the welding current and the welding voltage. The current detection means 10 is connected to the base material 3 to detect the welding current, and the voltage detection means 11 detects the welding voltage between the contact tip 5 a and the base material 3. FIG. 2 illustrates an example of the voltage / current waveform detected by these detection means.
[0027]
  The short-circuit waveform removing unit 12 removes S1 and S2, which are waveforms in the short-circuit period, from the current waveform in FIG. Specifically, a reference voltage for distinguishing between the arc period and the short circuit period is set as a threshold value by the threshold setting means 26 in the voltage waveform, and a current waveform corresponding to a voltage portion lower than this threshold is basically removed as the short circuit period. .
[0028]
  Thus, the technique for removing the short-circuit current waveform has been proposed in part in the prior art, for example, as in the comparator disclosed in Japanese Patent Publication No. 2-4396. However, in this way of distinguishing with the threshold as the boundary, in the portion immediately before the start of the short-circuit period and the portion immediately after the start of the arc period, a large disturbance factor other than the position information of the welding torch is not removed although it is slight in time. Remains.
[0029]
  Therefore, in the present invention, in addition to the short-circuit current waveform distinguished by the threshold value as shown in FIG. 2, the waveform portion expanded by a predetermined time T1, T2 before and after this current waveform is also removed as a short-circuit waveform. Specifically, the first calculation means 24 is provided for calculating the position of the welding current waveform corresponding to the time point a predetermined time T1 before the arrival point B1 that has reached the threshold in the welding voltage waveform as the short-circuit waveform removal start point C1, Moreover, the 2nd calculating means 25 which calculates the position of the welding current waveform corresponding to the time after the predetermined time T2 from the escape point B2 escaped from the threshold in the welding voltage waveform as the short-circuit waveform removal end point C2 is provided.
[0030]
  The first calculation means 24 and the second calculation means 25 are specifically expressed as time steps in the calculation program. Then, based on the calculation results of the first calculation means 24 and the second calculation means 25, the current waveform between the short-circuit waveform removal start point C1 and the short-circuit waveform removal end point C2 is deleted by the waveform deletion means 23. Specifically, the waveform erasing means 23 is represented by a waveform memory clear step in the calculation program.
[0031]
  For the previous time T1 and the subsequent time T2, for example, the previous time T1 is set to 1 msec, and the subsequent time T2 is set to 5 msec. However, the optimum value of this time varies depending on the welding conditions or the threshold value, and is set in consideration of specific conditions. In general, the current waveform immediately after the start of the arc is more unstable than the waveform immediately before the start of the short circuit. Therefore, it is usually preferable to set the later time T2 longer than the previous time T1.
[0032]
  The linear interpolation means 13 linearly interpolates the waveform missing portion caused by the short-circuit waveform removal described above, and connects the short-circuit waveform removal start point C1 and the short-circuit waveform removal end point C2 of FIG. 3 (A) Refer to the linear interpolation part of the lower waveform X). This linear interpolation is a measure for improving the calculation accuracy when calculating the deviation in the oscillating direction and the deviation in the torch axis direction in a later process, and is performed by a selection circuit as in the conventional Japanese Patent Publication No. 2-4396. By replacing the short-circuit welding current, which was completely discarded in the technology that extracts only the welding current signal during arc generation, with a linear current waveform without noise, the actual arc welding behavior is oscillated as much as possible. This is intended to be reflected in the calculation of deviation and torch axial deviation. Then, the moving average (the curve in FIG. 3B is a moving average curve) and differential waveform conversion in the subsequent process are effective for the first time by this linear interpolation.
[0033]
  The differential conversion means 14 converts the welding current waveform obtained by linear interpolation of the missing portion by the moving average after removing the short-circuit waveform described above (not shown in FIG. 3), and differentially converts the waveform to display it. Even if the groove width is narrower than the oscillation width by this differential conversion, the groove angle changes abruptly at the center position of the weld line, so that the differential waveform also changes greatly from the minus side to the plus side. With this differential transformation, information on the oscillating direction deviation and the torch axial direction deviation is obtained.With welding progressExtraction is possible almost in real time.
[0034]
  The cutting means 15 cuts the differentially converted current waveform into a plurality of sections corresponding to the oscillation period of the welding torch and divides the waveform Z of FIG. It is something to be issued. Here, “substantially equally” means that the time interval between the oscillating endpoints is not necessarily constant in a strict sense. Specifically, the cutting means 15 is controlled by an oscillating synchronization pulse signal output representing an oscillating end point in the welding robot system.
[0035]
  The extraction timing is given by the extraction trigger signal from the oscillation direction end point detection means 22. As the cutout trigger signal, the oscillating sync pulse signal may be used as it is.When outputtingAnd actual welding tochiosylate end pointWhen it arrivesIn this case, the delay time is detected in advance, and the extraction timing of the current differential conversion waveform by the extraction means 15 is set by delaying the delay time from the oscillating sync pulse signal by this delay time. desirable. The actual oscillating end point of the welding torch is measured by, for example, attaching a laser displacement sensor or the like to the welding torch, and the delay time is calculated by simultaneously measuring the ending point based on the oscillating sync pulse signal and the displacement sensor output. The delay time depends on the welding robot and welding conditions.Also fineSince it is strangely different, the delay time is detected prior to the welding operation.
[0036]
  As shown in FIG. 3D, the folding superposition means 16 folds (inverts) the waveform of one cycle of the oscillate smoothed by the moving average method and corresponding to the half cycle (180 degrees). ) To polymerize. By this folding polymerization means 16, the welding current differential waveformEach near the quarter and three quarter cyclesIt is possible to express the intersection of waveforms.
[0037]
  That is, in the conventional method using the approximate linear inclination angle for each oscillation cycle of the welding current waveform excluding the current waveform during the short circuit period, the welding current changes in the case of butt welding whose groove width is narrower than the oscillation width. Since the range is partial with respect to the oscillate range, it is almost impossible to display both shift amounts in the oscillate direction and torch axis direction and to perform shift correction control.
[0038]
  On the other hand, the present invention eliminates the welding current in the short-circuit period that becomes disturbance information in the torch position information, linearly interpolates between them, and differentially transforms the averaged current waveform to obtain a current corresponding to one cycle of oscillation. Oscillation direction shift information can be derived at the position where the differential waveforms intersect, and torch axis direction shift information can be derived from the welding current value at the differential zero position (position where there is no change in welding current).
[0039]
  The oscillation direction deviation display means 18 and the torch axis direction deviation display means 20 are typically a CRT screen or a liquid crystal screen for displaying an image as shown in FIG. 7, but the oscillation direction deviation amount δh and the torch axis line are displayed. It may be a display means for displaying the direction deviation amount δv or their temporal transition in an analog or digital manner. This image is displayed based on the calculation results of the oscillation direction deviation calculation means 17 and the torch axis direction deviation calculation means 19.
[0040]
  The calculation contents of both the calculation means 17 and 19 will be described below using the waveforms shown on the right side of FIGS. The waveform on the right side of each figure is obtained by folding and superposing the welding current differential waveform for one cycle of oscillation in a half cycle, and the vertical line written as the center of oscillate is one quarter (90 °) or quarter of the oscillate. This corresponds to three periods (270 °). However, unlike the waveform of FIG. 3C, the waveform itself is not an actual current differential waveform, but is convenient in consideration of the phenomenon that the welding current value increases and decreases depending on the length of the vertical distance between the welding torch 5 and the base material 3. This is a waveform created in
[0041]
  First, it is assumed that the waveform of FIG. 4 shows a normal welding state in which both the deviation in the oscillation direction and the deviation in the axial direction of the torch are zero. At this time, the intersection point P of the differential waveform coincides with the oscillate center position, and the welding current value at the current differential value zero position coincides with the reference height K. FIG. 5 shows a state where the oscillating direction shift δh is generated slightly to the left from the normal welding state of FIG. At this time, the constant vertical distance between the welding torch 5 and the base metal 3 on the left side from the center of the oscillate increases, so the left zero section of the welding current differential curve Z increases, and the maximum and minimum values of the differential curve ZStraight line connectingIs moved to the right from the center of oscillation. FIG. 6 shows a state in which the oscillating direction shift is greatly leftward from the groove center. At this time, since the constant vertical distance between the welding torch 5 and the base metal 3 on the left side from the center of the oscillation further increases, the left zero interval of the welding current differential curve Z further increases, and the intersection point P of the differential curve Z is oscillated. Move to the right from the center. It should be noted that the state in which the oscillating direction shift is generated on the right side is merely a symmetrical change in FIGS. 5 and 6 and will be omitted.
[0042]
  FIG. 7 shows a state in which the torch axial direction deviation δv is generated downward from the normal welding state of FIG. At this time, since the welding current increases in inverse proportion to the decrease in the vertical distance between the welding torch 5 and the base material 3, the welding current value at the differential waveform zero position moves upward while leaving the crossing position of the differential waveform unchanged. Therefore, the torch axis direction deviation amount δv = −αH can be expressed from the reference height K to the height H (calculated current value) at the current differential value zero position (α is a proportional constant and set by experimental data). It should be noted that the state in which the deviation in the torch axial direction occurs upward is omitted because it only shifts downward around the reference height K of the welding current value in FIG.
[0043]
  Next, the operation of the copying control apparatus will be described with reference to FIG. First, basic welding conditions such as an oscillation frequency, an oscillation amplitude width, and a welding torch height are input to the robot torch position control device 21 of the welding robot 1a. The welding robot 1 a starts a welding operation in response to the start signal, and performs arc welding while aiming at a plurality of predetermined teaching points provided along the welding line of the base material 3 with the welding torch 5.
[0044]
  The robot torch position control device 21 controls the torch position of the welding robot 1 a so that the oscillation center of the welding torch 5 follows the welding line. That is, while the oscillating center correctly follows the weld line (groove center) at the appropriate welding current, the crossing point P of the current differential waveform Z is in the oscillating direction deviation amount δh = 0 from the oscillating center as shown in FIG. The torch axial direction deviation amount δv = 0 is displayed by the current value at the current differential value zero position.
[0045]
  Further, when the center of the oscillation is shifted from the weld line in the left-right direction, as shown in FIGS. 5 and 6, the intersection P of the differential waveform Z is shifted from the center of the oscillation, and the displacement amount δh is zero. A signal from the shift calculation means 17 is input to the robot torch position control device 21.
[0046]
  Further, when the torch position deviates from the weld line in the vertical direction, as shown in FIG. 7, the torch axial direction deviation amount δv is calculated from the current value at the differential waveform zero position so that the deviation amount δv becomes zero. A signal from the torch axial direction deviation calculating means 19 is input to the robot torch position control device 21.
[0047]
  The actual control is a combination of oscillating direction control and torch axial direction control. The welding torch 5 is moved vertically and horizontally by the welding robot 1a so that the oscillating center of the welding wire 4 is along the welding line, and the welding current is It is controlled to be a predetermined value. Thus, based on the deviation amount data calculated by the oscillating direction deviation calculating means 17 and the torch axis direction deviation calculating means 19, the robot torch position control device 21 is set to make the deviation amount zero. A correction command is output, whereby the position of the welding torch 5 (oscillate center position and welding torch height) is feedback corrected.
[0048]
  A correction command is output to the robot torch position control device 21 based on the calculated values of the oscillating direction deviation calculating means 17 and the torch axial direction deviation calculating means 19, and the output values and the corrected calculating means 17 and 19 are calculated. By storing and accumulating values and learning the correlation between them, a method of using an optimum correction command instantaneously after that is possible.
[0049]
  Although one embodiment of the present invention has been described above, the present invention can be modified in various ways other than the above embodiment. For example, in the above embodiment, the moving average method is used to make the welding current into a smooth waveform. However, a method other than the moving average method or a method of converting to a smooth waveform by substantially the same method as the moving average method may be employed. In addition to the embodiment having both the oscillating direction deviation display means and the torch axial direction deviation display means, the copying determination apparatus of the present invention can have an embodiment in which the torch axis direction deviation display means is omitted depending on the application. is there.
【The invention's effect】
  The welding line scanning determination device and the scanning control device of the present invention have the following effects.
[0050]
  According to the first aspect of the present invention, not only the groove width of the weld base metal is wider than the oscillation amplitude range, but also the butt welding in which the groove width of the weld base material is narrower than the oscillation amplitude range. For example, it is possible to make a highly reliable determination of the weld line copying by arc sensing control.With welding progressSince it is possible to monitor accurately in real time, highly accurate detection for poor welding quality and reduction in the number of repairs after welding can be achieved.
[0051]
  Also,Claim1According to the invention described in the above, by appropriately setting the forward sampling time and the number of sampling of each moving averageWith welding progressAlmost real timeSlipA simple welding current waveform can be obtained.
[0052]
  Claim2According to the invention described in (5), since the influence of a short circuit which is a large disturbance factor is completely removed, disturbance information other than the welding torch position information generated during current detection can be removed as much as possible. Thereby, it is possible to accurately detect the misalignment of the arc from the weld line without depending on the welding conditions, the groove shape, and the root gap, and the reliability of the welding line copying determination is greatly improved.
[0053]
  Claim3According to the invention described in (1), since the extraction timing is delayed in advance by the delay time, the reliability of the determination is also improved.
[0054]
  Claim4According to the invention described in (1), it is possible to control the welding line scanning with high reliability by arc sensing control even for butt welding or the like in which the groove width of the weld base metal is narrower than the oscillation amplitude range. Since copying is instantaneously corrected, it is possible to prevent the occurrence of poor welding quality itself.
[0055]
  Claim5-6According to the invention described in claim 2 above,3The same effects as those of the invention described in (1) can be obtained for the control of the scanning of the weld line.
[0056]
  In addition, as a fundamental feature of arc sensing control, even when the target angle of the welding torch fluctuates, high-precision welding line scanning control is possible, which can reduce the number of teaching operations to the robot, and to some extent. Even if variations in parts accuracy or jigs occur, there will be no effect on the control of the welding torch, so the yield will be improved by lowering the part accuracy control level, and the cost will be reduced by simplifying the holding jig. be able to.
[0057]
  In addition, since the positional deviation is detected directly from the weld as an essential feature of arc sensing control, the conventional groove copying device becomes unnecessary, and various sensors essential to the groove copying device for welding torch etc. Since no obstacles are added, it is possible to improve the degree of freedom of the workpiece posture, improve the reliability in a bad environment such as sputtering, fume, arc heat, etc., and prevent the detection accuracy and durability from decreasing.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an outline of a welding line scanning control device according to an embodiment of the present invention.
FIG. 2 is a welding voltage / current waveform diagram of a welding torch.
3A is a welding voltage / current waveform diagram obtained by linear interpolation of a welding current waveform, FIG. 3B is a diagram showing a welding current waveform obtained by linear interpolation and a moving average curve thereof, and FIG. 3C is a derivative of the moving average curve. The figure which shows the welding current differential curve which converted, (D) is the figure which folded and superposed | stacked the welding current differential curve of 1 cycle of oscillate in a half cycle.
FIG. 4 is a model screen diagram of the copying display device when there is no copying.
FIG. 5 is a model screen diagram of the copying display device at the time of small deviation in the oscillating direction.
FIG. 6 is a model screen diagram of the copying display device at the time of large deviation in the oscillating direction.
FIG. 7 is a model screen diagram of the copying display device at the time of downward shift in the torch axis direction.
8A is a diagram showing a moving average curve of a welding current waveform linearly interpolated after the removal of a short-circuit period, FIG. 8B is a diagram showing an approximate straight line by turning a welding current curve of one cycle of oscillation in half a cycle; C) is a diagram in which a welding current differential curve of one cycle of oscillate is folded and polymerized in a half cycle.
[Explanation of symbols]
1 Consumable electrode gas shield arc welding equipment
1a Welding robot
2 Welding power supply
3 Base material
4 Welding wire
5 Welding torch
5a Contact chip
6 Feeding roller
7 Supply side
10 Welding current detection means
11 Welding voltage detection means
12 Short-circuit waveform removal means
13 Linear interpolation means
14 Differential transformation means
15 Cutting means
16 Folding polymerization means
17 Oscillating direction deviation calculation means
18 Oscillating direction deviation display means
19 Torch axial direction deviation calculating means
20 Torch axial direction deviation display means
21 Robot torch position controller
22 Oscillating direction end point detection means
23 Waveform eraser
24 1st calculating means
25 Second calculation means
26 Threshold setting means
27 Leveling means

Claims (6)

(A) Current detection means for detecting a welding current waveform when the welding torch is oscillated in a direction perpendicular to the welding line in butt welding of consumable electrode type arc welding in which short-circuiting and arc are repeatedly welded;
(B) a short-circuit waveform removing unit that removes a short-circuit waveform that is a welding current waveform in a short-circuit period from the welding current waveform detected by the current detection unit;
(C) linear interpolation means for interpolating a waveform missing portion of the welding current waveform from which the short-circuit waveform has been removed, with a straight line;
(D) leveling means for leveling the linearly interpolated welding current waveform into a smooth waveform by moving average ;
(E) differential conversion means for converting the smooth waveform into a differential waveform;
(F) cutting means for cutting the differential waveform into a plurality of sections corresponding to the oscillation period of the welding torch;
(G) a polymerization means for polymerizing the differential waveforms cut by the cutting means in a mutually inverted state every half cycle;
(H) The intersection of each waveform near the quarter and three quarter periods of the differential waveform found by the superposition means is the groove center position, and the position of the weld line center position with respect to the oscillating width direction of the welding torch. An apparatus for determining whether or not to copy a weld line, comprising: an oscillating direction shift display means for displaying a shift direction and a shift amount, respectively. Threshold setting means for setting the reference voltage for distinguishing the arc period and the short-circuit period in the welding voltage waveform as a threshold value, and the short-circuit waveform removing means a predetermined time before the arrival point at which the reference voltage in the welding voltage waveform is reached A first calculation means for calculating a position of the welding current waveform corresponding to the time as a short-circuit waveform removal start point, and a welding current corresponding to a time after a predetermined time from the escape point escaped from the reference voltage in the welding voltage waveform. Second calculation means for calculating the waveform position as a short-circuit waveform removal end point; and a short-circuit waveform removal start point and a short-circuit waveform removal end point based on the calculation results of the first calculation means and the second calculation means. weld line of the copying determination apparatus according to claim 1, characterized by comprising a waveform erase means for erasing the current waveform between. In order to reverse the welding torch at the oscillating end point, the time lag between when the oscillating sync pulse signal output from the robot torch position controller to the welding robot system is output and when the actual welding torch sill end point is reached is set. previously detected; then, the time lag only the oscillating welding line of the copying determination apparatus according to claim 1 or 2, wherein delaying the synchronizing pulse signal, characterized in that setting the cut timing of the welding current waveform by said cut-out means . (A) In butt welding of consumable electrode type arc welding in which short-circuit and arc are repeatedly welded, current detection means for detecting a welding current waveform when the welding torch is oscillated in a direction perpendicular to the welding line;
(B) a short-circuit waveform removing unit that removes a short-circuit waveform that is a welding current waveform in a short-circuit period from the welding current waveform detected by the current detection unit;
(C) linear interpolation means for interpolating a waveform missing portion of the welding current waveform from which the short-circuit waveform has been removed, with a straight line;
(D) leveling means for leveling the linearly interpolated welding current waveform into a smooth waveform by moving average ;
(E) differential conversion means for converting the smooth waveform into a differential waveform;
(F) cutting means for cutting the differential waveform into a plurality of sections corresponding to the oscillation period of the welding torch;
(G) a polymerization means for polymerizing the differential waveforms cut by the cutting means in a mutually inverted state every half cycle;
(H) The intersection of each waveform near the quarter and three quarter periods of the differential waveform found by the superposition means is the groove center position, and the position of the weld line center position with respect to the oscillating width direction of the welding torch. An oscillating direction deviation calculating means for calculating the deviation direction and the deviation amount, respectively;
(I) comparing a welding current value corresponding to a differential value zero of the differential waveform with a set current value, and calculating a deviation direction and a deviation amount of the welding torch in the torch axial direction; And (J) based on the calculation results of the oscillating direction deviation calculating means and the torch axial direction deviation calculating means, the oscillation center of the welding torch in a direction to eliminate the oscillating direction deviation and the torch axial direction deviation. weld line of the copying control device, characterized in that the torch height to feedback control. Threshold setting means for setting the reference voltage for distinguishing the arc period and the short-circuit period in the welding voltage waveform as a threshold value, and the short-circuit waveform removing means a predetermined time before the arrival point at which the reference voltage in the welding voltage waveform is reached A first calculation means for calculating a position of the welding current waveform corresponding to the time as a short-circuit waveform removal start point, and a welding current corresponding to a time after a predetermined time from the escape point escaped from the reference voltage in the welding voltage waveform. Second calculation means for calculating the waveform position as a short-circuit waveform removal end point; and a short-circuit waveform removal start point and a short-circuit waveform removal end point based on the calculation results of the first calculation means and the second calculation means. 5. The welding line scanning control device according to claim 4 , further comprising waveform erasing means for erasing the current waveform between the welding lines. In order to reverse the welding torch at the oscillating end point, the time lag between when the oscillating sync pulse signal output from the robot torch position controller to the welding robot system is output and when the actual welding torch sill end point is reached is set. 6. The welding line tracing control device according to claim 4 , wherein the welding line tracing control apparatus detects the welding current waveform by the cutting means in advance by detecting the delay time from the oscillation synchronizing pulse signal by the time lag. .

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