JP6537135B2 - Crater control method for 2-wire welding - Google Patents

Description

  The present invention is performed by generating an arc between the welding wire and the base material during the stationary period and feeding the filler wire from the welding wire to the insertion position at the rear from the welding wire to the molten pool formed by the arc 2 The present invention relates to a crater control method for wire welding.

  The two-wire welding method, in which the filler wire is fed while being in contact with the molten pool formed by the preceding consumable electrode arc while obliquely contacting the filler wire, uses two wires of the consumable electrode arc welding wire and the filler wire. Therefore, it is excellent in high-speed weldability and high weldability. In particular, when high-speed welding is performed by a two-wire welding method, it is important to feed the filler wire in contact with the molten pool from behind the consumable electrode arc in order to prevent it from becoming a humping bead. This is because when the filler wire is fed into the generation part of the consumable electrode arc and melted, the cooling effect of the molten pool is reduced, and the filler wire can not suppress the rise of the latter part of the molten pool, so that the humping It is because there is almost no effect which suppresses a bead. On the other hand, if the filler wire is brought into contact with the latter half of the molten pool outside the arc generation section and fed so as to be melted by the heat of the molten pool, the molten pool is efficiently cooled and the filler wire As a result, the rear half of the molten pool can be suppressed to suppress the formation of humping beads. In the following description, the wire of the consumable electrode arc will be described as a welding wire and will be distinguished from a filler wire. As a welding method for generating a consumable electrode arc, a carbon dioxide gas arc welding method, a mag welding method, a mig welding method, a pulse mag welding method, a pulse mig welding method, a consumable electrode alternating current pulse arc welding method or the like is used.

  At the end of two-wire welding, with the welding torch stopped, feed of the filler wire is stopped or decelerated, and crater control is performed by the consumable electrode arc. The reason for stopping or decelerating the filler wire feed during the crater control period is as follows. During the crater control period, in order to form a sound crater part, the feed speed of the welding wire is reduced to about 40 to 70% of the steady period. As a result, since the value of the welding current for energizing the consumable electrode arc also decreases, the temperature of the molten pool also falls below the steady period. For this reason, if the filler wire is fed to the molten pool at the same feeding speed as in the steady period during the crater control period, the filler wire may not be sufficiently melted and may cause melting failure. . Therefore, in the two-wire welding, during crater control, it has been general to stop or decelerate filler wire feeding to perform crater control.

  On the other hand, in the invention of Patent Document 1, the welding current is supplied to the filler wire during heating of the crater control period to heat the filler wire at the same feeding speed as in the steady period even during the crater control period. It will continue to pay.

  According to the invention of Patent Document 2, the distance between the welding wire and the filler wire is shortened during the crater control period to make it approach the arc, thereby providing the filler wire at the same feeding speed during the steady period as in the steady period. It will continue feeding.

  Here, crater control is to fill the weld pool and the filler wire into the molten pool which is in a state of being depressed by the pressure of the consumable electrode arc before the end of welding to form a healthy bead portion.

  Two-wire welding is often used in high speed welding at 1.5 m / min or more because high welding can be performed. In high speed welding, in order to melt the filler wire stably by the heat from the melting place, it is necessary to apply a large current to the arc to form a large molten pool. For this reason, the molten pool is largely depressed by the pressure from the consumable electrode arc. In such a state, if the feed speed of the filler wire is reduced as in the above-described prior art, the crater portion having an unhealthy shape may not be obtained because the large depression can not be filled. If the inventions of Patent Documents 1 and 2 are applied, it is not necessary to decelerate the filler wire, and a large depression can be filled. However, in order to apply the invention of Patent Document 1, another welding power source is required to apply a welding current to the filler wire. In order to apply the invention of Patent Document 2, a drive mechanism for shortening the distance between wires is required. In either case, there is a problem that the welding apparatus becomes expensive.

JP, 2013-59767, A JP, 2013-75303, A

  Therefore, the present invention provides a crater control method of two-wire welding which can shape the crater portion into a sound shape without adding a special device when performing high-speed welding by two-wire welding. To aim.

In order to solve the problems described above, the invention of claim 1 is
During steady-state period, an arc is generated between the welding wire and the base material, and a filler wire is fed from the welding wire to the insertion position rearward from the welding wire to the molten pool formed by the arc. In the crater control method,
When the welding torch reaches a predetermined welding end position, the feeding speed of the welding wire and the filler wire is reduced to continue the feeding, and the welding target position of the welding wire is set while the arc is generated. The welding wire and the filler wire are filled in the molten pool in a state of being depressed by the pressure of the arc during the steady period while stopping and rotating the insertion position of the filler wire around the welding aiming position as a center point Finish welding after performing crater control to form a bead
It is a crater control method of two wire welding characterized by the above.

In the invention of claim 2, the insertion position of the filler wire is rotated once.
It is a crater control method of two wire welding according to claim 1 characterized by things.

The invention according to claim 3 makes the insertion position of the filler wire make one rotation in the reverse direction after making one rotation.
It is a crater control method of two wire welding according to claim 1 characterized by things.

The invention of claim 4 rotates the insertion position of the filler wire while temporarily stopping at a predetermined angle.
It is a crater control method of two wire welding given in any 1 paragraph of Claims 1-3 characterized by the above-mentioned.

  According to the present invention, during the crater control period, the filler wire can be inserted from the entire circumferential direction instead of being inserted from one direction as in the prior art, so the filler wire decelerates and the welding amount The crater portion can be formed in a healthy shape even if the At this time, it is not necessary to add a special device.

It is a block diagram of the welding apparatus for enforcing the crater control method of two wire welding which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in FIG. 1 for demonstrating the crater control method of 2 wire welding which concerns on Embodiment 1 of this invention. It is a schematic diagram of the welding completion part which shows a mode of rotation of the insertion position b of the filler wire in crater control period Tc.

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

First Embodiment
In the invention of the first embodiment, in the crater control method of two-wire welding, during the crater control period, feeding of the welding wire and the filler wire is continued, and the welding electrode aiming position of the welding wire is maintained while generating the consumable electrode arc. Is stopped, and crater control is performed while rotating the insertion position of the filler wire with the welding aiming position as the center point.

  FIG. 1 is a block diagram of a welding apparatus for implementing a crater control method for two-wire welding according to a first embodiment of the present invention. Each component will be described below with reference to the figure.

  The welding apparatus includes a welding torch WT surrounded by a broken line, a welding power source PS, a robot controller RC, and a robot (not shown).

  The welding torch WT includes a feeding tip 4a for feeding power to the welding wire 1a, and a feeding guide 4b for guiding the filler wire 1b to the insertion position.

  A shield gas (not shown) such as carbon dioxide gas or a mixed gas of carbon dioxide gas and argon gas is spouted from the tip of the welding torch WT. The welding torch WT is held by a robot (not shown) and moved along the welding line in accordance with a work program stored in the robot controller RC. Therefore, along with the movement of welding torch WT, welding wire 1a and filler wire 1b move together. In the following description, the movement of the welding torch WT and the movement of the welding wire 1a and the filler wire 1b mean the same.

  The welding wire 1 a is fed at a welding wire feeding speed Ws in the welding torch WT by the rotation of the welding wire feeding roll 5 a coupled to the welding wire feeding motor WM, and is transferred between the welding wire 1 a and the base material 2. A consumable electrode arc 3a is generated.

  The filler wire 1b is fed at the filler wire feeding speed Fs inside the feeding guide 4b by the rotation of the filler wire feeding roll 5b coupled to the filler wire feeding motor FM, and the second half of the molten pool 2a It is inserted in the state where it was touched by. The welds in the figure show the state of the steady period.

  Welding voltage Vww is applied between welding wire 1a and base material 2, and welding current Iww is conducted in consumable electrode arc 3a. In the figure, the welding direction is left. A molten pool 2a is formed by the preceding consumable electrode arc 3a. No voltage is applied between the filler wire 1 b and the base material 2, and no current flows. The filler wire 1b is inserted in contact with the rear half of the molten pool 2a, and is melted by the heat from the molten pool 2a. The filler wire 1b is fed out of the generation part of the consumable electrode arc 3a. This is to prevent the filler wire 1b from being directly melted by the consumable electrode arc 3a as described above. The advancing angle of the welding wire 1a is in the range of about 0 to 30 °, and in the figure, it is the case of a straight face (0 °). The advancing angle of the filler wire 1b is in the range of 20 to 50 °. That is, the filler wire 1b is inserted in the diagonal forward direction.

  The center line which shows the feeding direction of the welding wire 1a is shown with a dashed-dotted line, and the point which this center line cross | intersects the base material 2 surface becomes the welding aiming position a. The insertion position of the filler wire 1b is the insertion position b. This insertion position b is set to a range behind the generation portion of the consumable electrode arc 3a and in front of the rear end of the molten pool 2a. The distance between the welding target position a and the insertion position b is the inter-wire distance Lw (mm). Here, the position of the welding torch WT during welding is the above-described welding aiming position a.

  Welding power source PS is a power source for applying welding current Iww to generate consumable electrode arc 3a by applying welding voltage Vww between welding wire 1a and base material 2 through feed tip 4a. is there. The welding power supply PS sends a welding wire feeding control signal Wc to the welding wire feeding motor WM to control the welding wire feeding speed Ws, and the filler for the filler wire feeding motor FM. The wire feed control signal Fc is sent to control the filler wire feed rate Fs. When the welding voltage Vww is applied from the welding power source PS via the power supply tip 4a, the welding wire 1a is on the + side. The distance between the tip of the feed tip 4a and the welding target position a is the distance Lt (mm) between the feed tip and the base material. The welding power supply PS is a power supply of a constant voltage characteristic as usual. Therefore, welding current (average value) Iww is determined by welding wire feeding speed Ws and the distance between the feeding tip and the base material Lt.

  The robot controller RC outputs the start signal On and the crater control period signal Tcs to the welding power source PS. The start signal On becomes High level during the steady period and the crater control period, and controls the output and the feed of the welding power source. The crater control period signal Tcs is at High level during a predetermined crater control period Tc from when the welding torch WT reaches the welding end position on the welding line taught in advance.

  FIG. 2 is a timing chart of each signal in FIG. 1 for explaining the crater control method of two-wire welding according to the first embodiment of the present invention. The same figure (A) shows the time change of start signal On, the same figure (B) shows the time change of crater control period signal Tcs, the figure (C) the time change of rotational speed Sf of the insertion position of a filler wire. The figure (D) shows the time change of welding wire feeding speed Ws, the figure (E) shows the time change of welding current Iww, the figure (F) shows the time of filler wire feeding speed Fs. Indicates a change. No voltage is applied to the filler wire 1b in both the steady period and the crater control period, and no current flows. This will be described below with reference to the same figure.

  In the figure, a time before t1 is a steady period, and while welding torch WT moves along a weld line at a predetermined welding speed, steady welding is performed as described later. A period of time t1 to t2 is a predetermined crater control period Tc, and crater control is performed as described later. After time t2, there is a short antistick process period of about 50 ms to prevent welding of welding wire, but this antistick process is the same as the conventional one and is not directly related to the present invention. , I have omitted here.

(1) Steady Period Before Time t1 Since the welding torch WT has not reached the welding end position taught in advance during the steady period before time t1, as shown in FIG. The high level (startup) takes place, and the crater control period signal Tcs goes low as shown in FIG. During the stationary period, the welding torch WT moves along the welding line at a predetermined welding speed. As shown in FIG. 6D, the welding wire feeding speed Ws is a predetermined value Ws1. As shown in the figure (E), the welding current Iww has a value I1 determined by the welding wire feeding speed Ws1. As shown in FIG. 6F, the filler wire feeding speed Fs is a predetermined value Fs1. The filler wire feeding speed Fs1 is about 20 to 40% of the welding wire feeding speed Ws1. As shown to the same figure (C), the rotational speed Sf of the insertion position of a filler wire is 0, and is not rotating.

(2) Crater control period Tc from time t1 to t2
When welding torch WT reaches the above welding end position at time t1, crater control period signal Tcs changes to the high level as shown in FIG. 6B, and at time t2 after crater control period Tc elapses. Return to low level. During the crater control period Tc, the welding torch WT stops at the welding end position. Therefore, the welding target position a of the welding wire 1a also stops at the welding end position. The consumable electrode arc 3a continues to be generated also during the crater control period Tc, and the welding wire feed speed Ws is decelerated from Ws1 to Ws2 during the steady period as shown in FIG. Since the welding wire feed speed Ws is reduced, the welding current Iww decreases from I1 to I2 during the steady period as shown in FIG. As shown in the figure (F), the filler wire feeding speed Fs decelerates from Fs1 to Fs2 during the steady period. The above Ws2 is set by the welding current I2 to a value at which burn-out does not occur, and the above Fs2 is set to a value that melts stably at the welding current I2.

  During the crater control period Tc, the welding aiming position a is stopped at the welding end position with the consumable electrode arc 3a generated. The welding torch WT is rotated by the operation of the robot with the welding aiming position a as a central point, and the insertion position b of the filler wire is rotated. For this reason, as shown to the same figure (C), rotational speed Sf of the insertion position of a filler wire becomes a positive value during crater control period Tc. A positive value of Sf indicates that it is rotating clockwise. When Sf is a negative value, it indicates that it is rotating in the reverse direction of the clock. Clockwise rotation is a case where the base material 2 is observed from the upper surface (the feeding direction of the welding wire 1a).

  When the crater control period Tc ends at time t2, as shown in FIG. 7B, the crater control period signal Tcs changes to low level, and as shown in FIG. 6A, the activation signal On is low level. Change to When the start signal On becomes Low level, the welding power source PS stops the output, so the welding wire feed speed Ws becomes 0 and the feeding is stopped as shown in FIG. As shown, the welding current Iww is 0, the energization is stopped and the consumable electrode arc 3a is extinguished. At the same time, as shown in FIG. 7F, the filler wire feeding speed Fs also becomes 0, and the feeding is stopped. As shown to the same figure (C), rotational speed Sf of the insertion position of a filler wire becomes 0, and rotation stops.

  FIG. 3 is a schematic view of the welding end portion showing rotation of the insertion position b of the filler wire during the crater control period Tc. The figure is the figure which looked at the base material 2 from the upper surface, and the molten pool 2a is formed in the welding completion position on the base material 2, and the bead is formed in the back. The welding end position is the welding target position a during stop and is indicated by a black point. The welding target position a is the center of rotation. A circle is drawn by a broken line centering on the welding target position a. This circumference is the rotation locus of the insertion position b of the filler wire. The position on the circumference at the rear from the welding target position a is the rotation angle 0 °, and the opposing position is the rotation angle 180 °. The method of rotating the insertion position b of the filler wire during the crater control period Tc is selected from the following three methods.

1) First Rotation Method As shown in FIG. 2C, the filler wire insertion position b is rotated 360 ° clockwise (0 rotation) from 0 ° during the crater control period Tc. That is, in a state where the consumable electrode arc 3a is generated at the welding target position a, crater control is performed by making one rotation while the filler wire 1b is inserted on the circumference. The direction of rotation may be counterclockwise. In this method, during the crater control period Tc, the feed rates of the welding wire 1a and the filler wire 1b are reduced more than during the steady period to continue the feed. Then, the insertion position b of the filler wire is rotated once around the consumable electrode arc 3a. Thus, the filler wire 1b can be inserted from the entire circumferential direction instead of being inserted from one direction as in the prior art, so that the soundness is good even if the filler wire 1b is decelerated to reduce the amount of welding. It is possible to form a crater portion of any shape.

2) Second rotation method During the crater control period Tc, the filler wire insertion position b is rotated 360 ° clockwise (0 rotation) from 0 °, and then rotated once again in the reverse direction. That is, in a state where the consumable electrode arc 3a is generated at the welding target position a, crater control is performed by rotating the filler wire 1b one turn after being inserted on the circumference and rotating it one more time in the reverse direction. The rotation direction of the first rotation may be counterclockwise. In this method, in addition to the effect of the method of 1), it is possible to return in a second rotation that the cable of the welding torch WT is wound around the robot rotation shaft in the first rotation, so Movement to the place becomes smooth.

3) Third Rotation Method The filler wire insertion position b is temporarily stopped at a predetermined angle while being rotated by the above first or second rotation method. The predetermined angles are, for example, 0 ° and 180 °. In this method, in addition to the effects of the first and second rotation methods, since the time length of the crater control period Tc can be easily adjusted by adjusting the pause time, welding conditions of Setting becomes easy.

  According to the first embodiment described above, during the crater control period, the feeding of the welding wire and the filler wire is continued, and the welding target position of the welding wire is stopped while the arc is generated, and the insertion position of the filler wire Crater control is performed while rotating the welding target position as the center point. Thus, in the first embodiment, the filler wire can be inserted from the entire circumferential direction instead of being inserted from one direction as in the prior art, so the filler wire is decelerated to reduce the amount of welding. Even if the crater portion has a sound shape, it can be formed. At this time, it is not necessary to add a special device.

1a welding wire 1b filler wire 2 base metal 2a molten pool 3a consumable electrode arc 4a feeding tip 4b feeding guide 5a feeding roller 5b for welding wire feeding roller a for filler wire a welding target position for welding wire b filler wire insertion position Fc Filler wire feed control signal FM Filler wire feed motor Fs Filler wire feed speed Iww Welding current Lt Feeding tip to base material distance Lw Distance between wires On Start signal PS Welding power source RC Robot controller Sf Inserting filler wire Position rotation speed Tc Crater control period Tcs Crater control period signal Vww Welding voltage Wc Welding wire feed control signal WM Feeding motor for welding wire Ws Welding wire feed speed WT Welding torch

Claims (4)

During steady-state period, an arc is generated between the welding wire and the base material, and a filler wire is fed from the welding wire to the insertion position rearward from the welding wire to the molten pool formed by the arc. In the crater control method,
When the welding torch reaches a predetermined welding end position, the feeding speed of the welding wire and the filler wire is reduced to continue the feeding, and the welding target position of the welding wire is set while the arc is generated. The welding wire and the filler wire are filled in the molten pool in a state of being depressed by the pressure of the arc during the steady period while stopping and rotating the insertion position of the filler wire around the welding aiming position as a center point Finish welding after performing crater control to form a bead
,
Crater control method for two-wire welding characterized in that. Making one rotation of the insertion position of the filler wire;
The crater control method of two-wire welding according to claim 1, characterized in that: After one rotation of the insertion position of the filler wire, another rotation is performed in the reverse direction.
The crater control method of two-wire welding according to claim 1, characterized in that: Rotating the insertion position of the filler wire while temporarily stopping at a predetermined angle,
The crater control method of two-wire welding according to any one of claims 1 to 3, characterized in that:

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