JPH0433549B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a two-electrode rotating arc fillet welding method.

[Prior art and its problems]

When fillet welding a vertical plate and a horizontal plate, a fillet welding method that allows for a long weld bead and accurate groove welding is desired, but conventionally,
There was no method that could meet such demands.

[Purpose of the invention]

An object of the present invention is to provide a two-electrode rotating arc fillet welding method that allows for a long weld bead length and accurate groove tracing control when fillet welding a vertical plate and a horizontal plate. be.

[Summary of the invention]

This invention aims a leading nozzle at a groove formed by a vertical plate and a horizontal plate, and supplies a leading electrode along with a shielding gas toward the groove by deviating from the central axis of the leading nozzle, generating a leading arc between the leading electrode and the groove while rotating the leading nozzle to form a lower bead;
A trailing nozzle is provided on the upstream side of the leading nozzle in the welding progress direction with an interval from the leading nozzle, the trailing nozzle is directed toward the lower bead, and the trailing electrode is deviated from the center axis of the trailing nozzle. and supply it together with a shielding gas toward the lower bead, and while rotating the trailing nozzle, generate a trailing arc between the trailing electrode and the lower bead to form an upper layer bead on the lower bead. However, at this time,
The vertical plate and the horizontal plate are fillet welded under the following conditions, and the rotational speed of the preceding arc (N _L ):
N ₀ , rotational diameter of the preceding arc (D _L ): 1 to 6
mm, direction of rotation of the preceding arc: When the vertical plate is placed on the right side when facing the welding direction, the direction of rotation of the preceding arc is counterclockwise when viewed from above the preceding nozzle, and left side when facing the welding direction. When _a perpendicular plate is arranged _at D _T ): (W _L -8mm) and 1mm
The rotational direction of the trailing arc is within the range (W _L + 6 mm) from whichever is larger, and when the vertical plate is placed on the right side facing the direction of welding progress, the direction of rotation of the trailing arc is clockwise when viewed from above the trailing nozzle. , when the vertical plate is arranged on the left side facing the direction of welding progress, the trailing nozzle rotates to the left when viewed from above; the distance between the leading electrode and the trailing electrode: the leading crater caused by the leading arc and the The distance between the trailing crater caused by the trailing arc and the trailing crater does not overlap. However, N ₀ : Before welding, the ratio of the vertical leg length (l ₁ ) to the horizontal leg length (l ₂ ) (l ₁ /l ₂ ) is maximum. The rotational speed of the arc determined in advance,
W _L : Detects the width of the lower bead, as well as any one of the voltage and current of the preceding arc, and detects the width of the lower bead within a predetermined range including the forwardmost point (C _f ) of the preceding electrode in the welding direction. The position of the preceding electrode corresponding to a change point in the variation value is detected, the preceding electrode is moved in the width direction of the groove based on a signal corresponding to the position of the preceding electrode, and the variation value is changed to the predetermined range. The difference between the integral value (S _cf ) obtained in this way and the reference value (E ₀ ) is calculated, and the preceding value is calculated so that the difference (S _cf −E ₀ ) becomes zero. The nozzle is moved in the direction of its center axis, and the fluctuation value of any one of the voltage and current of the trailing arc is detected, and a predetermined point including the forwardmost point (C' _f ) of the trailing arc in the welding direction is detected. detecting a position of the trailing electrode corresponding to a change point of the fluctuation value within a range, and moving the trailing electrode in the width direction of the groove based on a signal corresponding to the position of the trailing electrode; The fluctuation value is integrated over the predetermined range, and the integral value (S′ _cf ) obtained in this way is obtained.
and a reference value (E′ ₀ ), and move the trailing nozzle in the direction of its central axis so that the difference (S′ _cf −E′ ₀ ) becomes zero. It has the following.

[Structure of the invention]

The method of this invention will be explained with reference to the drawings.

FIG. 1 is a perspective view showing a vertical plate and a horizontal plate being fillet welded by the method of the present invention.

As shown in FIG. 1, a leading nozzle 1A rotating about a central axis is directed toward a groove formed by a vertical plate 2 and a horizontal plate 3. As shown in FIG. The leading electrode 4A is offset from the center axis of the leading nozzle 1A and is supplied together with the shielding gas toward the groove. The lower bead 5A is formed by a leading arc generated between the leading electrode 4A and the groove.

Trailing nozzle 1B rotating around the central axis
is provided on the upstream side of the preceding nozzle 1A in the direction of welding progress and is spaced apart from the preceding nozzle 1A.
It is directed towards A. The trailing electrode 4B is deviated from the central axis of the trailing nozzle 1B and is attached to the lower bead 5A.
is supplied together with shielding gas. The upper layer bead 5B is formed by a trailing arc generated between the trailing electrode 4B and the lower layer bead 5A.

When the vertical plate is placed on the right side facing the direction of welding progress, the leading arc rotates to the left when viewed from above the leading nozzle.On the other hand, when the vertical plate is placed on the left side facing the direction of welding progress, the leading arc rotates to the left of the leading nozzle. Rotate to the right when looking from above. The direction of rotation of the trailing arc is
When the vertical plate is placed on the right side facing the direction of welding progress, it rotates clockwise when viewed from above the trailing nozzle, and when the vertical plate is placed on the left side facing the direction of welding progression, it rotates clockwise when viewed from above the trailing nozzle. and rotate it to the left.

The reason why the rotation direction and rotation speed of the leading and trailing arcs are limited as described above will be explained.

First, the rotation direction and rotation speed of the trailing arc will be explained.

When the arc is rotated like the above-mentioned trailing arc, the effect of scooping up the molten metal that hangs down due to the influence of gravity is produced, and the length of the bead can be made equal. The scooping effect is related to the rotational speed of the arc, and when the welding current and welding speed are fixed, the scooping effect is maximized when the arc is rotated at an appropriate rotational speed (N ₀ ).

To determine the above appropriate rotational speed (N ₀ ), fillet welding is performed with the arc in the above-mentioned rotational direction at a predetermined welding current and a predetermined welding speed, and the vertical leg length (l ₁ ) and horizontal leg length (l ₂ ) The rotational speed of the arc at which the ratio (l ₁ /l ₂ ) is maximum can be found. Second
In the figure, the arc is set in the rotation direction mentioned above, and the welding current
Arc rotation speed (N) and leg length increase (l ₁ /l ₂ ) when fillet welding is performed at 300 A and welding speed of 22 cm/min.
Indicates the relationship between As is clear from FIG. 2, the appropriate rotation speed (N ₀ ) of the arc under the above-mentioned welding conditions is 7 Hz (420 revolutions/min). That is,
When the arc is rotated at this rotation speed, the leg length ratio (l ₁ /l ₂ ) is maximized. This shows that the effect of scooping up the molten metal due to the rotation of the arc is maximized, and the sagging of the molten metal can be prevented.

Therefore, in this invention, the vertical leg length (l ₁ )
In order to increase the length of the arc, the rotational direction and rotational speed of the trailing arc were limited as described above.

Next, the rotation direction and rotation speed of the leading arc will be explained.

When the direction of rotation of the arc is reversed, that is, when the vertical plate is placed on the right side when facing the direction of welding progress, the direction of rotation of the arc is counterclockwise when viewed from the top of the nozzle. On the other hand, when the vertical plate is placed on the left side in the direction of welding progress, the rotation direction of the arc is clockwise when viewed from the top of the nozzle, and the other conditions are as shown in Figure 2. When fillet welding was performed in the same manner as in the case of , it was found that the leg length ratio (l ₁ /l ₂ ) becomes minimum at the appropriate rotational speed (N ₀ ), as shown by the dotted line in Figure 2. Ta.

Therefore, in this invention, the horizontal leg length (l ₂ )
In order to increase the length of the arc, the direction and speed of rotation of the leading arc are limited as described above. FIG. 3 shows a cross-sectional view of a bead formed by the method of the present invention.

Next, in this invention, the reason why the rotational diameter (D _L ) of the leading arc is limited to a range of 1 to 6 mm will be explained.

If the rotating diameter (D _L ) of the leading arc is less than 1 mm, sufficient penetration will not be obtained, so the function of rotating arc welding will not be fully demonstrated. Tracing control cannot be performed accurately. On the other hand, when the rotational diameter (D _L ) of the leading arc exceeds 6 mm, the leading arc moves to the vertical plate 2.
If the horizontal plate 3 is too close to the horizontal plate 3, undercuts are likely to occur particularly on the vertical plate 1 side.

Therefore, in this invention, the rotational diameter (D _L ) of the leading arc is limited to a range of 1 to 6 mm.

Next, in this invention, the reason why the rotational diameter (D _T ) of the trailing arc is limited to the range of (W _L +6 mm) from the larger of (W _L −8 mm) and 1 mm will be explained. Here, (W _L ) is the third
As shown in the figure, the lower bead 5 due to the preceding arc
Indicates the width of A.

This is because if the rotational diameter (D _T ) of the trailing arc is less than the lower limit value, sufficient penetration cannot be ensured, and groove tracing control by the trailing electrode, which will be described later, cannot be performed with high accuracy. On the other hand, if the rotational diameter (D _T ) of the trailing arc exceeds the upper limit value, the trailing arc will come too close to the vertical plate 2 and the horizontal plate 3, and undercuts are likely to occur particularly on the vertical plate 2 side. Because it will be.

In this invention, the leading electrode 4A and the trailing electrode 4
A gap is provided between B and B so that the leading crater caused by the leading arc and the trailing crater caused by the trailing arc do not overlap, but this is done in order to prevent magnetic blowing and not to disturb the bead shape. This is to do so.

Next, a method of controlling the groove tracing of the leading electrode 4A in this invention will be explained.

Fig. 4 is a block diagram of the groove tracing control method of the leading electrode 4A, and Fig. 5 A shows fillet welding with the central axis of the leading nozzle facing the center (root) in the width direction of the groove. FIG.

4 and 5A, the leading arc voltage detector 6 detects the voltage between the groove and the leading electrode 4A rotating at a predetermined speed, that is, the leading arc voltage E. The switching device 7 detects the peak voltage position of the preceding arc voltage in a predetermined arc rotation range among the preceding arc voltages E detected by the preceding arc voltage detector 6 in accordance with a command signal from the controller, which will be described later. and integrator. The controller 8 operates the switch 7 based on the position signal of the leading electrode 4 detected by the leading electrode position detector 9 . Peak voltage position detector 1
0 is based on the preceding arc voltage E detected by the preceding arc voltage detector 6, the position signal of the preceding electrode 4 detected by the preceding electrode position detector 9, and the switching signal from the switching device 7. Within the predetermined arc rotation range, a voltage (E〓) corresponding to the position of the preceding electrode where the preceding arc voltage is maximum, that is, the point of change is detected. The voltage (E〓) corresponds to the phase difference of the preceding electrode from the reference position. Memory device 1
1 stores the voltage (E〓). The X-axis driver 12 drives the X-axis motor 13 for moving the preceding nozzle 1A in the groove width direction so that the voltage (E〓) stored in the memory 11 becomes zero.

The integrator 14 integrates the preceding arc voltage from the switching device 7 over the predetermined arc rotation range. The memory 15 stores the integrated value (S _cf )
remember. The differential amplifier 16 calculates the difference between the reference value (E ₀ ) corresponding to the preceding nozzle height set in advance by the reference voltage setter 17 and the integrated value (S _cf ). The Y-axis driver 18 drives the Y-axis motor 19 for moving the preceding nozzle 3 in its axial direction so that the calculated value of the difference (S _cf −E ₀ ) becomes zero.

The φ setting device 20 sets the predetermined arc rotation range in the controller 8 in advance. The n setting device 21 detects the peak voltage position and integrates the preceding arc voltage.
The number of rotations of the preceding nozzle 1A is set in advance in the controller 8. For example, when the number of times of peak voltage position detection and preceding arc voltage integration is set to a plurality of times by the n setter 21, the memory 11 stores the average value of the plurality of voltages (E〓). Meanwhile, the storage device 15 calculates the average value of the plurality of integral values (S _cf ).

Here, the predetermined arc rotation range is set to (φ ₀ ) by the φ setter 20, and the number of times of peak voltage position detection and preceding arc voltage integration is set to one by the n setter 21. The groove tracing control of the preceding nozzle 1A in the case of setting will be explained.

As shown in FIG. 5A, when the central axis of the leading nozzle 1A is oriented toward the center in the width direction of the groove, the leading arc voltage E detected by the leading arc voltage detector 6 is As shown in FIG. 6A, the maximum value is reached when the leading electrode 4 is closest to the vertical plate 2 and the horizontal plate 3, and the maximum value is reached when the leading electrode 4A is located at the center of the groove in the width direction.
In FIG. 6A, (C _r ) indicates the rearmost point of the preceding electrode 4A in the welding direction, as shown in FIG. indicates the point at which the leading electrode 4A approaches the vertical plate 2, (C _f ) indicates the most forward point of the leading electrode 4A in the welding direction, and R represents the point at which the leading electrode 4A approaches the vertical plate 2. The point when closest to the horizontal plate 3 is shown. Also, in Figure 7,
(C' _r ) indicates the rearmost point of the trailing nozzle 1B in the welding direction, (L') indicates the point when the trailing electrode 4B approaches the vertical plate 2 most, and (C' _f ) is
The forwardmost point of the trailing electrode 4B in the welding progress direction is shown, and (R') represents the point when the trailing electrode 4B approaches the horizontal plate 3 the most.

The predetermined arc rotation range (φ ₀ ) is a rotation range of the arc centered on the forwardmost point (C _f ), (C′ _f ) in the welding direction.

Next, as shown in FIG. 5B, the preceding nozzle 1A
When the center axis of is shifted toward the horizontal plate 3 along the X-axis direction, the leading arc voltage E detected by the leading arc voltage detector 6 is as shown by the solid line in FIG. 6B. , decreases as the leading electrode 4A approaches the vertical plate 2 and the horizontal plate 3, but the leading arc voltage when the leading electrode 4A approaches the horizontal plate 3 is the same as when the leading electrode 4A approaches the vertical plate 2. As shown in FIG. _6A , the position of the leading electrode where the leading arc voltage E is smaller than the arc voltage of It lags behind by (θ) compared to the case where it faces the center in the width direction. Leading electrode 4 where the leading arc voltage is maximum
The position of A is detected as a voltage (E〓) by the peak voltage position detector 10. X-axis motor 13
moves the preceding nozzle 1A in the X-axis direction so that the voltage (E〓) becomes zero.

Next, as shown in FIG. 5C, the preceding nozzle 1A
When the central axis of the is shifted toward the vertical plate 2 along the X-axis direction, the preceding arc voltage E detected by the preceding arc voltage detector 6 is as shown by the solid line in FIG. 6C. , decreases as the leading electrode 4A approaches the vertical plate 2 and the horizontal plate 3, but the leading arc voltage when the leading electrode 4A approaches the vertical plate 2 is the same as when the leading electrode 4A approaches the horizontal plate 3. As shown in FIG. _6A , the position of the leading electrode where the leading arc voltage E is smaller than the arc voltage of It moves forward by (θ) compared to the previous case where it faces the center in the width direction. Leading electrode 4A where the leading arc voltage is maximum
The position of is detected as a voltage (-E〓) by the peak voltage position detector 10. X-axis motor 13
moves the preceding nozzle 1A in the X-axis direction so that the voltage (-E〓) becomes zero.

Next, when the position of the preceding nozzle 1A in the Y-axis direction changes, the predetermined arc rotation range (φ ₀ ) calculated by the integrator 14 is determined by the differential amplifier 16.
_The difference between the integral value (S _cf ) of the preceding arc voltage at and the reference value (E ₀ ) is calculated, and _the Y-axis motor 19 is
moves the preceding nozzle 1A in the Y-axis direction.

In this way, groove tracing welding using the leading electrode 4A is performed with high precision.

Next, there is a groove tracing control method for the trailing electrode 4B in this invention, which is the same as that for the leading electrode 4A, so a description thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to increase the leg length of the fillet weld bead, and moreover, it brings about very useful effects such as being able to precisely control the groove tracing by the leading and trailing electrodes.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing fillet welding performed by the method of the present invention, FIG. 2 is a graph showing the relationship between leg length ratio and arc rotation speed, and FIG. FIG. 4 is a cross-sectional view of a weld bead obtained by the method of the present invention. FIG. 4 is a block diagram of the groove tracing control method for leading and trailing electrodes in this invention. FIG. Figure B is a front view showing that the leading and trailing electrodes are biased toward the horizontal plate, and Figure C is a front view showing the leading and trailing electrodes facing toward the center in the width direction of the groove. FIG. 6A is a front view showing a state in which the electrodes are biased toward the vertical plate side, and FIG. 6A is a graph showing changes in the leading and trailing arc voltages when the leading and trailing electrodes face the center in the groove width direction. , Figure B is a graph showing changes in leading and trailing arc voltages when the leading and trailing electrodes are biased towards the horizontal plate, Figure C is
The figure is a graph showing changes in the leading and trailing arc voltages when the leading and trailing electrodes are biased toward the vertical plate, and FIG. 7 is a plan view showing the rotational positions of the leading and trailing electrodes. In the drawings, 1A... Leading nozzle, 1B... Trailing nozzle, 2
... Vertical plate, 3... Horizontal plate, 4A... Leading electrode,
4B... Trailing electrode, 5A... Lower layer bead, 5B...
...Upper layer bead, 6... Leading (trailing) arc voltage detector, 7... Switching device, 8... Controller, 9... Leading (trailing) electrode position detector, 10... Peak voltage position detector , 11...Memory device, 12...X-axis driver, 13...X-axis motor, 14...Integrator,
15...Memory device, 16...Differential amplifier, 17...
Reference voltage setting device, 18...Y-axis driver, 19
...Y-axis motor, 20...φ setting device, 21...n
Setting device.

Claims (1)

[Claims] 1. A leading nozzle is directed toward a groove formed by a vertical plate and a horizontal plate, and a leading electrode is displaced from the center axis of the leading nozzle and is supplied together with a shielding gas toward the groove. While rotating the preceding nozzle, a preceding arc is generated between the preceding electrode and the groove to form a lower layer bead, and a space is provided between the preceding nozzle and the preceding nozzle on the upstream side of the welding progress direction. a trailing nozzle is provided, the trailing nozzle is directed toward the lower bead, a trailing electrode is displaced from a central axis of the trailing nozzle and is supplied together with a shielding gas toward the lower bead, and the trailing nozzle is While rotating, a trailing arc is generated between the trailing electrode and the lower layer bead to form an upper layer bead on the lower layer bead, and at this time, the vertical plate and the horizontal plate are arranged based on the following conditions. Fillet welding, rotational speed of the preceding arc (N _L ): N ₀ , rotational diameter of the preceding arc (D _L ): 1 to 6 mm, direction of rotation of the preceding arc: perpendicular to the right side facing the welding direction. When a plate is arranged, the preceding nozzle rotates counterclockwise when viewed from above; when a vertical plate is arranged on the left side facing the direction of welding progress, it rotates clockwise when viewed from above the preceding nozzle; and the rotational speed of the trailing arc (N _T ): N ₀ , rotational diameter of the trailing arc (D _T ): (W _L −8
mm) and 1 mm, whichever is larger (W _L + 6 mm), the rotational direction of the trailing arc: when facing the welding progress direction and placing a vertical plate on the right side, from above the trailing nozzle Rotation to the right when viewed from above; When a vertical plate is placed on the left side facing the direction of welding progress, rotation to the left when viewed from above the trailing nozzle. Distance between the leading electrode and the trailing electrode: Depends on the leading arc. An interval such that the leading crater and the trailing crater caused by the trailing arc do not overlap, provided that N ₀ : The ratio of the vertical leg length (l ₁ ) to the horizontal leg length (l ₂ ) (l ₁ /l ₂ ) is the maximum. The rotating speed of the arc, which is determined in advance before welding, W _L : width of the lower layer bead; furthermore, the fluctuation value of any one of the voltage and current of the preceding arc is detected, and the leading electrode is determined in the forwardmost direction in the welding direction. The position of the preceding electrode corresponding to the change point of the variation value is detected within a predetermined range including point (C _f ), and the position of the preceding electrode is adjusted to the width of the groove based on the signal corresponding to the position of the preceding electrode. the fluctuation value is integrated over the predetermined range, the difference between the integral value (S _cf ) thus obtained and the reference value (E ₀ ) is calculated, and the difference (S _cf − The preceding nozzle is moved in the direction of its center axis so that E ₀ ) becomes zero, and the fluctuation value of any one of the voltage and current of the following arc is detected, and the welding progress of the following nozzle is detected. The position of the trailing electrode corresponding to the change point of the fluctuation value is detected within a predetermined range including the forwardmost point in the direction (C _f ′), and the position of the trailing electrode is detected based on the signal corresponding to the position of the trailing electrode. The electrode is moved in the width direction of the groove, the fluctuation value is integrated over a predetermined range, and the difference between the integral value (S′ _cf ) thus obtained and the reference value (E′ ₀ ) is calculated. A two-electrode rotating arc fillet welding method, characterized in that the trailing nozzle is moved in the direction of its central axis so that the difference (S' _cf - E' ₀ ) becomes zero.