JPH0426939B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a rectangular weaving pattern welding method that can automatically weld even relatively wide grooves, and is particularly suitable for lamination welding. It is.

[Conventional technology]

When the base metal to be welded is thick and the groove depth is deep, lamination welding is conventionally performed, and in order to improve welding work efficiency, welding is performed in one pass for each layer while weaving the welding torch. It is being done.

For example, as shown in Figure 9, when welding a V-shaped groove 1 with a large groove angle θ of about 60 degrees, move the welding torch diagonally forward as shown in Figure 10. Weaving is performed in a trapezoidal shape that is a combination of the movements a and b and the forward movement c at both ends.

[Problem that the invention seeks to solve]

However, due to laminated welding, the weld width changes to W + ΔW in the cross section of the groove (Fig. 9a). This change also occurs due to processing of the groove line, meandering thermal deformation, etc. (FIG. 9b).

Therefore, while weaving the welding torch in a trapezoidal shape, the welding torch is moved forward c
When welding with a constant amount of , the bead pitch P increases in response to a change in the welding width W and becomes P+ΔP.
For this reason, the locus of the welding torch differs in the width forward direction and in the left and right diagonal directions, resulting in fusion failure 2.

Therefore, the traverse speed and forward speed of the welding torch must be controlled so as not to cause fusion defects, making automatic welding difficult.

On the other hand, in order to perform automatic welding, it is necessary to detect the welding width W due to changes in the cross-sectional shape of the groove, and to detect meandering of the groove in the direction of the weld line.

For this reason, in the conventional TIG welding method, changes in the arc voltage between the welding base metal and the electrode are used as a tracing signal, but the arc voltage changes significantly depending on the current due to the arc characteristics. .

Therefore, it is difficult to perform copy welding using this arc voltage.

Furthermore, in the conventional trapezoidal weaving method,
Since the welding posture is such that welding is performed while the welding torch is held perpendicular to the welding base metal, there is also the problem that poor penetration at both end walls of the groove tends to occur.
In addition, when stack welding V-shaped grooves, if you try to automatically weld the first layer where the sharp groove tips are facing each other, the amount of heat increases and burn-through is likely to occur, so manual welding etc. There is also the problem that automatic welding must be performed afterwards.

This invention solves the problems of welding torch weaving shape, welding torch posture, and scanning sensor based on the above-mentioned conventional technology, and makes it possible to automatically weld from the first layer, which requires adjustment of the amount of heating, by rectangular weaving scanning welding. The purpose is to provide the following.

[Means for solving problems]

This invention achieves this object by providing a welding torch that can travel in the direction of the welding line, move in parallel in a direction perpendicular to the welding line, and rotate around the tip of the electrode. A tracing sensor is installed to trace the groove line, and the welding torch is weaved in a rectangular shape along the groove shape based on the signal from this tracing sensor.For the first layer, the welding torch position is perpendicular to the groove line using a low pulse welding current. After welding in parallel mode so that The present invention is characterized in that copy welding is performed while switching between three welding posture modes including a rotation mode.

[Effect]

The welding torch is moved in the direction of the welding line and parallel movement in the direction perpendicular to the welding line, and is weaved into a rectangular shape that does not move during parallel movement to prevent fusion failure due to changes in the welding width. For the first layer, automatic welding is possible by setting the welding torch in parallel mode perpendicular to the groove line to suppress the amount of heating caused by the low pulse welding current and welding only with rectangular weaving, and for the next layer, the welding torch Furthermore, the welding torch can be rotated around the electrode tip in a plane orthogonal to the welding line, and the posture of the welding torch can be adjusted by a combination of parallel movement and rotational movement perpendicular to the groove surface, or by independent movement of each. This method prevents poor penetration at both end walls of the groove by appropriately selecting the configured welding posture mode, and further enables copy welding by using signals from copy sensors provided on both sides of the electrode.

〔Example〕

An embodiment of the present invention will be specifically described below with reference to the drawings.

As shown in FIG. 1, an example of an automatic welding device to which the rectangular weaving profile welding method of the present invention is applied includes a welding cart 11 that runs by itself on a dedicated rail 10 laid along the welding line L direction. , this welding cart 11 is provided with a parallel movement mechanism 13 perpendicular to the welding line L via a vertical movement mechanism 12. Rotating mechanism 1 that rotates as
A welding torch 16 is attached to the tip of the welding torch 5, and the welding torch 16 is controlled in four axes.

Copying sensors 17 and 18 are respectively attached to both sides of the welding torch 16 across the welding line L, and their tips are brought into contact with the welding base material near the electrode 14.

Further, at the tip of the electrode 14 of the welding torch 16,
Welding wire 20 via welding wire feeding mechanism 19
is now available for delivery.

Each of these mechanisms is composed of well-known mechanisms such as a linear or arcuate rack, pinion, servo motor, feed screw mechanism, etc., and is controlled by a control device (not shown).

The basic operation of such an automatic welding device is to weave the welding torch 16 into a rectangular shape as shown in FIG. 2, and to weave the welding torch 16 in combination with this, as shown in FIG. 3a. like,
Parallel movement while remaining perpendicular (parallel mode), rotational movement around the electrode tip (rotation mode) as shown in figure b, and parallel and rotational movement at the same time as shown in figure c. It consists of synthetic movements (parallel/rotation mode).

The tracing sensors 17, 18 and their signal detection circuits, which are essential for automatic welding while switching such basic operations, are constructed as shown in FIGS. 4 and 5.

That is, the tracing sensors 17 and 18 are made of thin metal wires, and a voltage is applied between them and the welding base material 3.

Therefore, during automatic tracing welding, the voltage or current between the welding base material 3 and the tracing sensors 17, 18 causes the tracing sensors 17, 18 to move to the groove walls 1a, 18.
By detecting that 1b is touched, it is possible to detect the state in which the electrode 14 approaches the groove walls 1a, 1b.

These copying sensors 17, 18 and groove walls 1a, 1b
For example, as shown in FIG.
The positive voltage is led to the left scanning sensor 17 via the resistor R1, the negative voltage is guided to the right scanning sensor 18 via the resistor R2, and the zero voltage is connected to the resistors R3 and R4. It is led to the welding base material 3 through the welding base material 3.

Moreover, this rectified voltage is applied to the diode D1,
The voltage is applied to a circuit including a light emitting diode D _f 1, a transistor Q1, and a resistor R5, and a circuit including a resistor R5, a transistor Q2, a light emitting diode D _f 2, and a diode _D2 .
D _f 2 has a phototransistor Q _f 1, Q _f
2 are combined.

Furthermore, the voltage at the connection point between resistors R3 and R4 is applied to the bases of transistors Q1 and Q2 through resistor R6.
The voltage is applied via the .

Therefore, when the left copying sensor 17 touches the left groove wall 1a, the transformer 22 → diode bridge 23 → resistor R1 → left copying sensor 17 →
Welding base material 3 → Resistor R3 → Resistor R4 → Transformer 22
Current flows through the path, the base potential of transistors Q1 and Q2 becomes positive, transistor Q1 is turned on, light emitting diode D _f 1 emits light, and the touch signal left is obtained at the output 24 of phototransistor Q _f 1. It will be done.

Also, when the right copying sensor 18 touches the right groove wall 1b, the transformer 22 → resistor R4 → resistor R
3 → Welding base material 3 → Right copying sensor 18 → Resistor R2
→Current flows through the path of diode bridge 23,
The base potentials of transistors Q1 and Q2 become negative, transistor Q2 is turned on, light emitting diode D _f 2 emits light, and phototransistor Q _f 2
A touch signal right is obtained at the output 25 of .

Therefore, by detecting touch signals from the output terminals 24 and 25, it is possible to detect a touch between the copying sensors 17 and 18 and the welding base material 3.

Next, such two copying sensors 17 and 18
The basic operation of automatically weaving the welding torch 16 into a rectangular shape using the will be described with reference to FIGS. 6 and 7.

FIG. 6 shows a torch trajectory on a plane by the rectangular weaving method.

First, the welding torch 16 is moved rightward by the parallel movement mechanism 13 (a), and when the right copying sensor 18 detects that it has touched the right groove wall 1b, the parallel movement mechanism 13 is stopped. Next, welding cart 1
1 and corrects the parallel movement mechanism 13 to move it forward along the right groove wall 1b (c), and when it has moved a predetermined distance (or a predetermined time), stop the forward movement and at the same time move the parallel movement mechanism 13 to the left. The welding torch 16 is moved in the direction. (b).

Then, the left copying sensor 17 is attached to the left groove wall 1a.
When it is detected that is touched, parallel movement mechanism 1
3, move the welding cart 11 forward, correct the parallel movement mechanism 13, move it along the left groove wall 1a (d), and stop the forward movement after moving a predetermined distance (or a predetermined time). At the same time, the parallel movement mechanism 13 is moved to the right (a), and the above operation is repeated.

A flowchart for realizing such a series of operations (a→c→b→d) is shown in FIG. 7, and will be explained step by step.

(1) Install the welding cart 11 etc. at a predetermined position, and also install the welding torch 16 and copying sensors 17, 1.
When the welding start operation 26 is performed after preparations such as positioning the welding torch 8 within the groove 1 are completed, the welding torch 16 is driven rightward by the parallel movement mechanism 13 (27).

(2) When the right copying sensor 18 touches the right groove wall 1b (28), the parallel movement is stopped and the welding cart 11 is moved forward (30).

(3) When this welding cart 11 is moving forward, C
corrects and controls the parallel movement mechanism 13 so as to maintain the state in which the right copying sensor 18 touches or does not touch the right groove wall 1b (32-35).

That is, when the right tracing sensor 18 moves away from the right groove wall 1b, the parallel movement mechanism 13 drives the welding torch 16 to the right (toward the right groove wall 1b), and moves the welding torch 16 toward the right groove wall 1b. If you touch the wall 1b, it will move to the left. By doing this, even if the right groove wall 1b is curved in the middle, welding can be performed while following this curve.

(4) When the welding cart 11 moves forward for a predetermined time (or a predetermined distance), it is stopped (36).

(5) Next, the welding torch 16 is driven to the left by the parallel movement mechanism 13 (37).

(6) When the left tracing sensor 17 touches the left groove wall 1a, the parallel movement mechanism 13 is stopped and the welding cart 11 is moved forward (41).

(7) When the welding cart 11 is moving forward, the above
Similarly to (3), the left copying sensor 17 is connected to the left groove wall 1.
The parallel movement mechanism 13 is controlled and corrected so as to maintain the state of whether or not a is touched (42 to 45).

That is, when the left copying sensor 17 moves away from the left groove wall 1a, the parallel movement mechanism 13 is driven to the left (in the direction toward the left groove wall 1a) and touches the left groove wall 1a. If so, the parallel movement mechanism 13 is driven to the right. By doing this, even if the left groove wall 1a is curved in the middle, welding can be performed while following this curve.

(8) When the welding cart 11 moves forward for a predetermined time (or a predetermined distance), it is stopped (46).

(9) Next, the welding torch 16 is moved to the right by the parallel movement mechanism 13 (27), and the above-mentioned operation is repeated, thereby realizing automatic welding by rectangular weaving that follows the groove 1.

That is, even if the welding width W of the groove 1 changes to W + ΔW due to the number of laminated layers or welding deformation, or if the welding line L is curved or meandering, automatic welding by rectangular weaving can be performed following this.

Next, we will explain the control sequence shown in FIG. 8 for the three welding posture modes necessary to control the posture of the welding torch 16 during rectangular weaving and automatically weld from the first layer to the top layer depending on the lamination state, etc. This is explained by:

(A) Single-wall parallel movement mode In this single-wall parallel movement mode, the welding torch 16 moves toward the welding base material 3 as shown in FIG. 3a.
It is held perpendicular to the
Two timers T ₁ , T ₂ built into the control device
Therefore, the welding current I is maintained at a low value I ₁ during the time T ₁ during which the welding cart 11 is moving forward (for example, T ₁ =
0.5 sec, I ₁ = 100 A), while the welding current I is maintained at a high value I ₂ (for example, T ₂ = 0.5 sec, I ₂ = 250 A) during the time T ₂ when the welding cart 11 is stopped. Another set of T ₁ and T ₂ is combined to correspond to rectangular weaving. In addition, in the figure, ΔT is the timer.
T is the delay time when switching ₁ .

In this initial layer welding, pulse welding is performed in a parallel mode in which the welding torch is kept vertical with rectangular weaving while switching the welding currents I1 and I2 to 100A or 250A every 0.5 seconds, for example.

That is, in A in FIG. 8, T1 and T2 are shown in a considerably enlarged state, but the first layer of the V-shaped groove is a linear groove with a very small welding width W, and is a rectangular weaving. Even so, almost linear movement with almost no lateral movement is required, and automatic movement can be achieved by tracing only the wall surface of one groove, and since there is no lateral movement, rectangular weaving is used to move forward and stop. It will run automatically while repeating the process.

On the other hand, in the first layer of a V-shaped groove, the sharp parts of the base metal face each other, and if the amount of heating increases, burn-through will occur, making it difficult to weld the next layer and subsequent layers with the same welding current. , T1, T2, the welding currents I1, I2 are changed, and by employing a low pulsed welding current, welding without burn through can be achieved.

By using this translation mode,
Automatic welding of the butt groove of the first layer becomes possible,
While the welding cart 11 is running, the two tracing sensors 1
While selecting one of the groove walls 7 and 18 by switching a selection switch or the like, one groove wall 1a or 1b is moved along the groove wall 1a or 1b.

Further, in order to maintain the electrode 14 at the tip of the welding torch 16 at a constant distance from the surface of the welding base material 3, an arc voltage control system (AVC) is adopted to control the vertical movement mechanism 12.

(B) Single-wall rotational movement mode In this single-wall rotational movement mode, the welding torch 16 is basically rotated left and right around the tip and moved in a fan shape, as shown in FIG. 3b. It is composed of four stages corresponding to rectangular weaving.

The stage is a state in which the welding torch 16 is rotated to the right by the rotation mechanism 15 until it reaches the set torch angle.

The stage is a state in which the torch angle has reached the right set value, and the timer T ₁ operates at this stage, and the stage is reached when the timer T ₁ is reached.

The stage is a state in which the welding torch 16 is tilted to the left, opposite to the stage, by the rotation mechanism 15 until the torch angle reaches the left set value.

The stage is in a state where the torch angle has reached the left set value, timer T ₂ works in this stage, and when T ₂ time is reached, returns to the stage,
Repeat from now on.

In addition, in this one-wall copying rotation movement mode, 2
The two copying sensors 17 and 18 are switched with a selection switch and copying welding is performed using only one copying sensor 17 (or 18), and the welding width W is set to a preset value, so the welding line L does not curve or meander. However, it is used when the welding width W is constant during at least one layer of welding.

Unlike the above-mentioned one-wall parallel movement mode, when the welding torch 16 is tilted to the left in order to improve the accuracy of tracing the groove wall 1a (or 1b) even when the welding torch 16 is tilted, the right The scanning sensor 18 is operated.

(C) Double-wall copying combined movement mode In this double-wall copying combined movement mode, the welding torch 16 is moved in a combination of parallel movement and rotational movement, as shown in FIG. The electrode 14 at the tip of the groove 1 is always
It is made up of four stages corresponding to rectangular weaving.

The stage simultaneously moves the welding torch 16 in the right direction by the parallel movement mechanism 13,
The rotating mechanism 15 tilts the welding torch 16 so that its tip faces toward the right wall, and drives the welding torch 16 until the right tracing sensor 18 detects the right groove wall 1b. At this stage, the vehicle is in a stopped state.

The stage is in a state where the right copying sensor 18 detects the right groove wall 1b and the parallel movement mechanism 13 and rotation mechanism 15 are stopped at that position.
At this stage, timer T ₁ operates, and when the time reaches T ₁ , the stage is reached. In addition, in the figure,
ΔT is a slight delay time until the start of running when switching from stage to stage.

At the same time, the stage moves the welding torch 16 in parallel to the left by the parallel movement mechanism 13.
The rotating mechanism 15 tilts the welding torch 16 so that its tip faces toward the left wall, and drives the welding torch 16 until the left copying sensor 17 detects the left groove wall 1a. In this stage as well, the running is stopped.

The stage is in a state where the left copying sensor 17 detects the left groove wall 1a and the parallel movement mechanism 13 and rotation mechanism 15 are stopped at that position.
The length of this stage, i.e. welding torch 1
The advance of 6 is determined by the set time T ₂ of timer T ₂ ,
The vehicle starts running after a short delay time ΔT.

Then, when the set time _T2 of this timer _T2 is reached, the process returns to the stage and repeats from then on.

In addition, the stage and welding torch 16
It is also possible to move the stage forward slightly and move it diagonally, but in order to make the trajectory of the stage parallel to the trajectory of the stage, for example, if you move the stage forward, then move the stage backward by a corresponding amount. Preferably, rectangular weaving is maintained.

In addition, welding current I and welding wire supply amount F
are each stage of double wall copying composite movement mode ~
is controlled as shown in the figure.

According to such a double-wall copying composite movement mode, the welding width W changes in the direction of the welding line L, and W+
Even if there is a part where ΔW occurs, automatic welding can be performed following this pattern, making it widely applicable to lamination welding.

Three welding posture modes (A), (B), (C) as above
By combining this with the rectangular weaving described above, even if the groove shape is not linear and the welding width W changes, it is possible to automatically weld everything from the first layer to the top layer.

〔Effect of the invention〕

As specifically explained above in conjunction with the embodiments, according to the present invention, the welding torch is rectangular weaved and at the same time the orientation of the welding torch is switched according to a plurality of preset welding orientation modes. Since automatic tracing is performed by the tracing sensor, automatic tracing welding can be performed in response to changes in the angle and depth of the groove, meandering of the weld line, and welding width.

That is, since the tracing sensors are arranged on both sides of the welding torch, it is possible to trace the groove line near the electrode without any delay time.

In addition, since multiple welding posture modes can be set for the welding torch and welding is performed while switching between them, the welding posture mode that corresponds to the shape of the groove enables automatic welding of the first layer, which was previously difficult to weld without leaving. It is now possible to weld all layers without leaving.

Furthermore, since one of the movements of the welding torch is rotational movement around the tip, the angle of the welding torch within the groove can be changed greatly, which increases penetration into the groove wall surface and improves welding quality. can be improved.

Furthermore, since the welding torch is weaved in a rectangular shape, changes in the welding width can be handled without changing the parallel movement speed or traveling speed, and there is no possibility of fusion failure.

Furthermore, one of the movements of the welding torch is a composite movement that combines parallel movement and rotational movement around the tip, and in this case, the welding torch cannot always be kept at a constant distance from the groove surface. , the aiming position of the electrode within the groove becomes stable, and welding preparation etc. become easier.

These effects solve the four problems that the present application was intended to solve as described above.

(1) To solve the problem of poor fusion caused by changes in the weld width W and bead pitch P (Fig. 9 a, b), a rectangular shape that combines running movement in the weld line direction and parallel movement in the direction orthogonal to this This is solved by weaving, and by rectangular weaving, even if the melting width W changes, the bead pitch P can be kept constant, thereby preventing poor fusion.

(2) To solve the problem of automatic welding that is difficult due to detecting the weld width W and meandering of the groove by changing the arm voltage, the groove shape is set on both sides of the weld line near the electrode of the welding torch. Since it is equipped with a tracing sensor that traces the groove wall and uses touch signals to the groove wall,
Even if the welding width W changes, the groove wall can be easily detected, facilitating automatic welding.

(3) To solve the problem of poor penetration at both end walls of the groove due to holding the welding torch perpendicular to the base metal, we have adopted a combination of three posture modes for the welding torch, and the tip of the electrode The welding torch can be always pointed at the groove wall surface in a rotation mode centered around , a parallel mode in which the electrode remains perpendicular, and a parallel/rotation mode that combines these two, which can prevent poor penetration. .

(4) To solve the problem that automatic welding of the first layer of a V-shaped groove is difficult due to burn-through, etc., by welding with rectangular weaving with the welding torch in parallel mode using pulsed welding current, we can form a sharp groove. By minimizing the amount of heat applied to the first layer where the tips are facing each other, burn-through is prevented and automatic welding is possible.

In addition, it is a highly versatile welding method that can be applied not only to TIG welding but also to MIG welding and submerged welding.

[Brief explanation of drawings]

Figures 1 to 8 show an embodiment of the rectangular weaving profile welding method of the present invention, Figure 1 is a schematic configuration diagram of an automatic welding device using this welding method, and Figures 2 and 3 are respectively Explanatory diagram of basic operation, 4th
5 and 5 are perspective views of the scanning sensor and its detection circuit diagram, FIGS. 6 and 7 are explanatory diagrams of the locus of the welding torch by rectangular weaving, and a control flowchart, and FIG. 8 is the control of the welding posture mode. An explanatory diagram of the sequence, FIGS. 9a and 9b are explanatory diagrams of an example of a welding target, and FIG. 10 is an explanatory diagram of conventional weaving. 1... Groove, 1a, 1b... Left and right groove walls, 1
1... Welding cart, 12... Vertical movement mechanism, 13...
Parallel movement mechanism, 14... Electrode, 15... Rotation mechanism, 16... Welding torch, 17, 18... Left and right copying sensors, 19... Welding wire feeding mechanism, 20
...Welding wire.

Claims (1)

[Claims] 1. A welding torch that can travel in the direction of the welding line, parallel to the direction perpendicular to the welding line, and rotate around the electrode tip is equipped with a tracing sensor that copies the groove shape on both sides of the welding line near the electrode. The welding torch is weaved in a rectangular shape along the groove shape based on the signal from the scanning sensor, and the first layer is welded in parallel mode using a low pulse welding current so that the welding torch is perpendicular to the groove line. , weaving the next layer into a rectangular shape, and at the same time changing the welding torch's posture so that it always faces the groove wall surface according to the groove shape of each layer, there are three welding posture modes: parallel mode, rotation mode, and parallel/rotation mode. A rectangular weaving pattern welding method characterized in that pattern welding is performed while switching.