JP2011056553A - Method for profiling control with arc sensor in rotary submerge arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for profiling control with an arc sensor in a rotary submerge arc welding which can realize proper profiling control with an arc sensor even in rotary submerge arc welding in which arc generation points cannot be visually confirmed due to covering with a flux. <P>SOLUTION: In performing submerge arc welding utilizing high heat produced by the generation of arc between a welding wire 22 and a base metal or between welding wires under a particulate flux 20, a target position is regulated so that a difference is constant between integral values SL and SR of arc voltage value or arc current value in a predetermined domain of integration that is bilaterally symmetrical with respect to a forward central point Cf, in a welding advance direction in a rotary circle of arc, in a predetermined rotary condition range having regularity between the forward central point Cf and the arc voltage waveform or the arc current waveform. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a scanning control method using an arc sensor for rotary submerged arc welding, and in particular, accurately controls a target position even in submerged arc welding in which an arc generation point is covered with a flux and visual confirmation cannot be performed. The present invention relates to a scanning control method using an arc sensor of rotary submerged arc welding that can be performed.

  As illustrated in FIG. 1, submerged arc welding is known in which an arc is generated between the welding wire 22 and the base material 10 or between the welding wires under the granular flux 20 and welding is performed using high heat generated thereby. In this submerged arc welding, a granular flux 20 is deposited on the base material 10 in advance, and welding is performed by inserting the tip of the welding wire 22 therein. The arc is covered with the flux 20 and is not visible from the outside. The flux 20 contributes to the blocking of the atmosphere and the refining action of the weld metal, and contributes to the formation of the slag 26 and the weld bead 28. In the figure, 12 is a backing material, and 24 is an electrode.

  This submerged arc welding is widely used for shipbuilding, bridge welding of bridges, BOX columns and pressure vessels of high-rise buildings. Since it is possible to employ a large current and multiple electrodes, it has high efficiency (high welding speed) and deep penetration, but the welding posture is downward as illustrated in FIG. 2 or illustrated in FIG. However, most of the construction is downward. 2 and 3, reference numeral 14 denotes a standing plate (for example, a flange of an H-shaped steel material), and 16 denotes a lower plate (also a web). In addition, most of the rod handling methods are straight, and there are cases where they are swung partially.

  In the downward posture illustrated in FIG. 2, thick wire and high current welding are applied, and high efficiency and high quality (deep penetration, good bead appearance), but the workpiece posture is changed so that the welding posture is downward. In the case of H-shaped steel, only one joint on one side of the web can be constructed.

  On the other hand, in the horizontal posture illustrated in FIG. 3, two joints on both sides of the web can be simultaneously applied even in the case of an H-shaped steel material, but bead sagging occurs due to the action of gravity, and the horizontal fillet as illustrated in FIG. In welding, shortage of the upper leg length or undercut is likely to occur. Furthermore, on the long leg side where the leg length is long, the drooping appearance is poor, the shape of the bead toe portion is bad, and it is very difficult to put a large leg long fillet weld having a length of 10 mm or more in a horizontal posture to practical use.

  Most of arc welding is applied to automatic trolleys (equipment). However, in the case of submerged arc welding, the arc generation point is covered with flux and cannot be confirmed visually, so the true target position adjustment is possible. Is very difficult. Conventional technologies include (1) mechanical carriage copying with guide rollers, etc. that keep the carriage in contact with the member to be welded and maintain the electrode positional relationship with the member, and (2) aiming at the carriage rail. Or (3) a method of controlling the position by pressing a potentiometer (position sensor) with a roller at the tip against the member to be welded. It was.

  That is, position control using mechanical copying or a potentiometer can only control the positional relationship between the electrode and the portion where the guide roller or sensor is in contact, and accurately copies the crossing portion of the member, the groove root portion, and the like. It is not possible. Also, it cannot cope with thermal deformation during welding. Furthermore, in the case of tandem welding or multi-pass welding, there is a problem that it is impossible to set the target position with respect to the leading electrode or the bead shape of the previous pass.

  Here, in the case of downward welding as illustrated in FIG. 2, the tolerance of appropriate welding conditions is wide, so that the scanning accuracy is not a big problem. However, in the case of a horizontal posture as illustrated in FIG. Since the tolerance of the condition is narrow, it has a problem that it leads to a bead failure (insufficient upper leg length or undercut).

  On the other hand, in gas shielded arc welding that does not use flux, as proposed by the applicant in Patent Document 1, as shown in FIG. 4, welding line copying control in rotating arc welding in which the tip of the welding wire 22 is rotated is proposed. ing. In the figure, 23 is an arc.

  FIG. 5 shows an example of the definition of the arc rotation position. Here, in the arc of rotation of the arc, the front center point in the welding progress direction is Cf, the rear center point is Cr, the standing plate 14 side is the R side, and the lower plate 16 side is the L side.

Also, taking the target position x _p of the welding torch on an axis 21 perpendicular to the nozzle rotating shaft 25, the x _p when the aiming position of the welding torch is consistent with the weld line WL is set to x _p = 0, x _p With respect to = 0, the standing plate 14 side (R side when indicated by the arc rotation position in FIG. 5) is defined as plus, and the lower plate 16 side (L side when represented by the arc rotation position in FIG. 5) is defined as minus.

  In the arc sensor welding line scanning control method, as shown in FIG. 5, the left and right (L, R) phase angle θ is in the same range (for example, 5 ° <θ <180 °) around the Cf point for each rotation of the arc. For example, the arc voltage value is integrated, and the difference (SR−SL) between the integrated value SR of the arc voltage value on the vertical plate (R) side and the integrated value SL of the arc voltage value on the lower plate (L) side is calculated. Take out as an output and automatically correct the target position of the welding torch according to the value and sign of (SR-SL).

That is, the output (SR-SL) of the arc sensor is SR-SL = 0 when the target position of the welding torch coincides with the weld line (x _p = 0) as shown in FIG. Therefore, welding is advanced as it is. As shown in FIG. 6B, when the aiming position of the welding torch is shifted to the lower plate 16 side (x _p <0), the arc length is longer on the vertical plate 14 side than on the lower plate 16 side. Since it becomes longer and SR-SL> 0, a command is given to correct the target position of the welding torch toward the upright plate 14 side. Further, as shown in FIG. 6C, when the target position of the welding torch is shifted to the standing plate 14 side (x _p > 0), the arc length is lower on the lower plate 16 side than on the standing plate 14 side. Since it becomes longer and SR-SL <0, a command is given to correct the target position of the welding torch toward the lower plate 16 side.

As apparent from FIG. 5, around the _{x p = 0, SR-SL} = 0, since the output of the arc sensor (SR-SL) the sign is positive or negative reversal, the aiming position of the welding torch is vertical plate 14 side or When it is shifted to the lower plate 16 side, the target position of the welding torch may be corrected in the direction in which SR-SL = 0 is always achieved.

  Therefore, it is conceivable to apply the welding line scanning control by the arc sensor used in the rotary gas shielded arc welding to the submerged arc welding.

Japanese Patent Laid-Open No. 3-114670

  However, when the inventor tried to apply the gas shielded arc welding technique to submerged arc welding as it was, it turned out that it did not work. That is, in gas shielded arc welding, the relationship between the Cf signal and the arc voltage waveform is as shown in FIG. 7 regardless of the rotation frequency, and the arc voltage waveform has regularity, but in submerged arc welding, as shown in FIG. An ideal rotating arc welding-voltage waveform relationship could not be obtained.

  The present invention was made to solve the above-mentioned conventional problems, and by applying the copy control of gas shielded arc welding as it is, appropriately control the conditions of submerged arc welding in which the copy control does not work, It is an object to enable scanning control by an arc sensor.

  The present invention generates an arc between a welding wire and a base metal or between welding wires under a granular flux, and when performing submerged arc welding using the high heat generated thereby, The difference between the integrated value of the arc voltage value or the arc current value in a predetermined integration region symmetrical with respect to Cf in the predetermined rotation condition range having regularity between the front center point Cf and the arc voltage waveform or the arc current waveform. The above-mentioned problem is solved by controlling the target position so as to be a constant value.

  Here, the predetermined rotation condition range can be made larger than the rotation frequency 3 Hz and smaller than 30 Hz.

  Further, the predetermined integration region can be a region of 90 ° left and right centering on Cf.

  According to the present invention, copying control by an arc sensor is possible even in submerged arc welding. Therefore, although the arc is not visible due to the flux, the target position is not controlled based on nearby members, but the target position can be controlled by the current and voltage data of the generated arc itself. It becomes possible to cope with deformation and the bead shape of the preceding electrode and the previous pass.

The perspective view which shows the principle of the submerged arc welding which this invention makes object Sectional view showing an example of downward welding Cross section showing an example of horizontal fillet welding Perspective view showing the state of rotary arc welding in gas shielded arc welding Diagram showing definition of arc rotation position Diagram showing the relationship between the target position of the welding torch and the output of the arc sensor An example of ideal rotating arc welding-voltage waveform The figure which shows the example of the relationship between Cf signal in 7 Hz, and an arc voltage / current waveform for demonstrating the principle of this invention. The figure which similarly shows the example of the relationship between Cf signal and arc voltage / current waveform in 3 Hz The figure which similarly shows the example of the relationship between Cf signal in 30 Hz, and an arc voltage / current waveform The perspective view which shows the outline | summary of 1st Embodiment of this invention. Figure showing the integration region The figure which also shows a control circuit The perspective view which shows the outline | summary of 2nd Embodiment of this invention. The perspective view which shows the outline | summary of 3rd Embodiment of this invention. The figure which shows the electrode arrangement | positioning of 3rd Embodiment. The perspective view which shows the outline | summary of 4th Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  For rotating submerged arc welding, the inventor conducted an experiment at a torch angle of 50 ° and a welding speed of 40 cpm by rotating the tip of a 1.6 mm diameter welding wire at a rotating diameter of 3 mm and counterclockwise CCW so as to scrape the weld bead. As shown in FIG. 8 (example of a rotation frequency of 7 Hz) between a Cf position and an arc voltage / current waveform when a predetermined rotation condition range, for example, the rotation frequency is larger than 3 Hz and smaller than 30 Hz, Regularity was obtained in which the peak voltage was at the front Cf position and the bottom voltage was at the rear 180 ° position. Data having no regularity in the Cf signal and the voltage (current) signal at 3 Hz and 30 Hz are shown in FIGS. 9 and 10, respectively.

  The rotation condition range also has a limit of the rotation diameter, and can be defined by the rotation pitch.

  The present invention has been made on the basis of the above knowledge. In the first embodiment, in single rotation submerged arc welding, as shown in FIG. 11, the tip of the welding wire 22 is counterclockwise CCW at a rotation frequency of 3 Hz to 30 Hz. , The arc voltage value is integrated in a predetermined 90 ° horizontal integration centered on Cf, and the difference between the integrated values SL and SR (SL−SR) is obtained as shown in FIG. The target position is controlled so that it is detected and becomes a constant value (for example, 0). Note that the target position of (SL-SR) may be set to a value other than 0, and the target position may be offset from the welding destination.

  FIG. 13 shows a block circuit diagram of an arc sensor welding line copying control apparatus used when the present invention is implemented.

  In the figure, 31 is an arc voltage detector, 32 is a welding current detector, 33 is a switch, and is connected to the arc voltage detector 31 here. When controlling by welding current, switch 33 is switched to the welding current detector 32 side.

  An arc rotation position detector 35 detects the arc rotation position (Cf, R, Cr, L) shown in FIG. Reference numeral 36 denotes a timing pulse generator which inputs the arc rotation position detected by the arc rotation position detector 35 and outputs the timing pulse to the L side integrator of the arc voltage Ea so that the integration region becomes a predetermined angle range. 37 and the R-side integrator 38 are commanded.

  The angle range commanded by the timing pulse generator 36 is 0 ° to 90 ° left and right in this example. This angle range is set in advance, and is set to 0 ° to 90 ° in the present example as described above, but is not limited to this and may be symmetrical.

  Reference numeral 39 denotes a differential amplifier that calculates the difference between the L-side integral value SL by the L-side integrator 37 and the R-side integral value SR by the R-side integrator 38. The differential amplifier 39 outputs an arc sensor output (SL-SR). ) Is required.

  The obtained arc sensor output (SL-SR) is input to the weld line scanning control circuit 40. In the welding line scanning control circuit 40, the scanning distance is calculated based on the deviation signal of the differential amplifier 39, the motor 41 is controlled based on the calculation result, and the welding torch 47 is scanned.

  In the present embodiment, the upper leg leg length can be extended by widening the penetration on the standing plate 14 side.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, in the same single rotation submerged arc welding as in the first embodiment, the welding wire 22 is scraped and rotated in the clockwise direction CW opposite to that in the first embodiment.

  In the present embodiment, the lower leg 16 side can be widened to extend the lower leg leg length.

  Next, a third embodiment of the present invention will be described with reference to FIG. In the present embodiment, in tandem rotary submerged arc welding, the welding wire 22A of the leading electrode 24A is a straight rod that does not rotate, and the tip of the welding wire 22B of the trailing electrode 24B is rotated counterclockwise in the counterclockwise direction CCW. It is a thing.

  An arrangement example of the nozzle rotation shaft 25A of the preceding electrode 24A and the nozzle rotation shaft 25B of the subsequent electrode 24B is shown in FIG.

  In the present embodiment, by rotating the welding wire 22B of the trailing electrode 24B, it is possible to widen the penetration on the standing plate 14 side, extend the length of the upper leg, and cope with the leading electrode 24A.

  Note that, as in the fourth embodiment shown in FIG. 17, the tip of the welding wire 22A of the leading electrode 24A is also scraped and rotated, for example, in the clockwise direction CW to widen the penetration on the lower plate 16 side and extend the leg leg length. You can also.

  In the above-described embodiment, the predetermined rotation frequency range is larger than 3 Hz and smaller than 30 Hz, and the predetermined integration region is a left and right 90 ° region centered on Cf. The integration region is not limited to this, and can be changed according to, for example, the rotation diameter.

  The application object of the present invention is not limited to horizontal fillet welding, and can be directed to downward welding or butt welding of flat plates having a groove shape.

14 ... Standing plate 16 ... Lower plate 20 ... Flux 22, 22A, 22B ... Welding wire 24, 24A, 24B ... Electrode 28 ... Welding bead

Claims (3)

When generating an arc between the welding wire and the base metal or between the welding wire under granular flux, and performing submerged arc welding using the high heat generated by this,
In a predetermined rotation condition range where there is regularity between the front center point Cf in the welding progress direction in the arc rotation circle and the arc voltage waveform or arc current waveform,
Copying by rotary arc-merged arc welding using an arc sensor characterized in that the target position is controlled so that the difference between the integral values of arc voltage values or arc current values in a predetermined integral region symmetrical about Cf is constant. Control method.   2. The scanning control method using an arc sensor of rotary submerged arc welding according to claim 1, wherein the predetermined rotation condition range is greater than a rotation frequency of 3 Hz and less than 30 Hz.   2. The scanning control method using an arc sensor of rotary submerged arc welding according to claim 1, wherein the predetermined integration region is a region of 90 ° left and right centering on Cf.