JP2016187820A - Welding starting method of 2-wire welding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To excellently keep a welding quality of a welding starting part, even if a short circuit is caused, in 2-wire welding.SOLUTION: In a welding starting method of 2-wire welding executed by feeding while contacting a filler wire with a rear half part of a molten pool formed by an arc generated between a welding wire and a base material, feeding Fs of the filler wire is started at time t6 when a heat gain correlation value Sd (an integral value of a multiplication value of a welding current Iww and welding voltage Vww in an arc period) to the base material from an electric conduction starting time t2 of the welding current Iww reaches a reference value. Thus, even if a short circuit is caused between the welding wire and the base material in a transitional period of welding starting time, since the feeding of the filler wire is started at time when the molten pool grows to a proper size when heat gain to the base material reaches the reference value, the filler wire can be transferred to a stable molten state, and a welding quality of a welding starting part can be excellently kept.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a welding start method for two-wire welding in which an arc is generated between a welding wire and a base material and the filler wire is fed while being brought into contact with the latter half of a molten pool formed by the arc. Is.

  The two-wire welding method in which the filler wire is fed while being brought into contact with the molten pool formed by the consumable electrode arc is a high-speed weldability because two wires of the consumable electrode arc and the filler wire are used. And excellent weldability. In particular, when high-speed welding is performed by the 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 a humping bead. This is because when the filler wire is fed into the consumable electrode arc and melted, the cooling effect of the molten pool is reduced, and the rise of the latter half of the molten pool cannot be suppressed by the filler wire. This is because there is almost no suppression effect. On the other hand, if the filler wire is fed in contact with the second half of the molten pool at the peripheral edge of the arc and melted by the heat of the molten pool, the molten pool is efficiently cooled and melted by the filler wire. The latter half of the pond is suppressed and the formation of the humping bead can be suppressed. In the following description, the wire of the consumable electrode arc is described as a welding wire and is distinguished from the filler wire. As a welding method for generating a consumable electrode arc, a carbon dioxide arc welding method, a mag welding method, a MIG welding method, a pulse mag welding method, a pulse MIG welding method, a consumable electrode AC pulse arc welding method, or the like is used.

  The welding start method of two-wire welding is generally performed as follows (see, for example, Patent Document 1). When an activation signal is input from the outside to the welding device, feeding of the welding wire is started and a welding voltage is applied between the welding wire and the base material. When the welding wire comes into contact with the base material, a welding current is passed to generate a consumable electrode arc. When the welding current starts energization, the welding torch starts moving along the previously taught weld line. In addition, the filler wire feeding is started after a delay of a predetermined period from the start of the welding current. During this predetermined period, the molten pool is gradually enlarged by the consumable electrode arc. When the filler wire comes into contact with the molten pool, the tip of the filler wire is melted by the heat from the molten pool, the contact state is maintained, and the state shifts to the steady welding state. No current is passed through the filler wire. The predetermined period is a period until the molten pool formed by the consumable electrode arc grows to a size including the insertion position of the filler wire and the temperature of the molten pool reaches a value at which the filler wire can be melted. is there. The predetermined value varies depending on the joint shape, the thickness of the base material, the material of the base material, and the like, and is, for example, about 0.4 to 1.0 seconds.

  In the above-described conventional welding start method, it is assumed that a consumable electrode arc is generated when the welding wire comes into contact with the base material and the welding current is energized, and the consumable electrode arc is continuously generated thereafter. Yes. In such a state, feeding the filler wire starts at the timing when the molten pool has grown to an appropriate size by optimizing the predetermined period according to the welding conditions. Transitions to a stable molten state in contact with the pond.

  However, even if the welding wire comes into contact with the base material and a welding current is applied, the short-circuit state may continue for a long time and the generation of a consumable electrode arc may be delayed. Further, even if the consumable electrode arc once occurs substantially simultaneously with the energization of the welding current, the consumable electrode arc may temporarily extinguish due to a short circuit state thereafter. Thus, the consumable electrode arc may be temporarily extinguished several times during the transition period until the transition to the steady welding state at the start of welding. In such a state, feeding of the filler wire is started before the molten pool grows to an appropriate size during the predetermined period. As a result, there has been a problem that the filler wire cannot be stably melted in contact with the molten pool, and the welding quality at the welding start portion is deteriorated.

JP 2013-711145 A

  Therefore, in the present invention, even if a short circuit occurs between the welding wire and the base material during the transition period at the start of welding, the filler wire can be shifted to a stable molten state, and the welding quality of the welding start portion It is an object of the present invention to provide a welding start method for two-wire welding that can keep the temperature good.

In order to solve the above-described problems, the invention of claim 1
In the welding start method of two-wire welding, in which an arc is generated between the welding wire and the base material and the filler wire is fed in contact with the latter half of the molten pool formed by the arc,
When welding is started, feeding of the welding wire is started, and when the welding wire comes into contact with the base material, a welding current is energized, and the heat input correlation to the base material from the start of energization of the welding current Start feeding the filler wire when the value reaches a predetermined reference value,
This is a welding start method for two-wire welding.

In the invention according to claim 2, the heat input correlation value is a time integral value of the generation period of the arc.
The welding start method for two-wire welding according to claim 1, wherein:

In the invention of claim 3, the heat input correlation value is an integral value of the welding current during the arc generation period.
The welding start method for two-wire welding according to claim 1, wherein:

In the invention of claim 4, the heat input correlation value is an integral value of a product of the welding current and the welding voltage during the arc generation period.
The welding start method for two-wire welding according to claim 1, wherein:

  According to the present invention, even if a short circuit occurs between the welding wire and the base material during the transition period at the start of welding, the amount of heat input to the base material reaches the reference value, and the molten pool has grown to an appropriate size. Since the feeding of the filler wire is started at the time, the filler wire can be shifted to a stable molten state, and the welding quality at the welding start portion can be kept good.

It is a block diagram of the welding apparatus for enforcing the welding start method of 2 wire welding which concerns on Embodiment 1 of this invention. It is a timing chart of each signal in Drawing 1 for explaining a welding start method of two-wire welding concerning Embodiment 1 of the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1]
In the invention of the first embodiment, when welding is started, feeding of the welding wire is started. When the welding wire comes into contact with the base material, a welding current is energized, and the base material from the start of energization of the welding current is applied. When the heat input correlation value reaches the reference value, the filler wire starts to be fed.

  1 is a configuration diagram of a welding apparatus for carrying out a welding start method of two-wire welding according to Embodiment 1 of the present invention. Hereinafter, each component will be described with reference to FIG.

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

  The welding torch WT includes carbon dioxide, carbon dioxide and argon from the tip of the welding torch WT provided with a feeding tip 4a for feeding the welding wire 1a and a feeding tip 4b for guiding the feeding of the filler wire 1b. A shielding gas (not shown) such as a mixed gas with gas is ejected. The welding torch WT is held by a robot (not shown) and moved along the weld line according to a work program stored in the robot controller RC.

  The welding wire 1a is fed to the inside of the welding torch WT at the welding wire feeding speed Ws by the rotation of the welding wire feeding roll 5a coupled to the welding wire feeding motor WM. A consumable electrode arc 3a is generated.

  The filler wire 1b is fed through the welding torch WT at the filler wire feed speed Fs by the rotation of the filler wire feed roll 5b coupled to the filler wire feed motor FM. No voltage is applied to the filler wire 1b, and no current is applied.

  A welding voltage Vww is applied between the welding wire 1a and the base material 2, and a welding current Iww is conducted in the consumable electrode arc 3a. In the figure, the welding direction is the left direction. A molten pool 2a is formed by the preceding consumable electrode arc 3a. The filler wire 1b is inserted in contact with the latter half of the molten pool 2a, and is melted by heat from the molten pool 2a. The filler wire 1b is fed outside 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 same figure, it is a case of a straightness (0 °). The advance angle of the filler wire 1b is in the range of 20 to 50 °. That is, the filler wire 1b is inserted diagonally forward.

  The welding current detection circuit ID detects the welding current Iww and outputs a welding current detection signal Id. The welding voltage detection circuit VD detects the welding voltage Vww and outputs a welding voltage detection signal Vd.

  The current energization determination circuit CD determines that the welding current Iww is energized from the value of the welding current detection signal Id, and outputs a current energization determination signal Cd which is at a high level.

  The arc discriminating circuit AD discriminates that an arc is generated from the value of the welding voltage detection signal Vd and outputs an arc discriminating signal Ad which becomes a high level.

The correlation discriminating circuit SD receives the welding current detection signal Id, the welding voltage detection signal Vd, the current energization discrimination signal Cd, and the arc discrimination signal Ad as inputs, and performs the following processing 1) to 3) to 1). The heat input correlation value is calculated by selecting one, and a correlation determination signal Sd that becomes a High level when the heat input correlation value reaches a predetermined reference value is output. The reference value is set by experiment to a value at which the weld pool has an appropriate size.
Process 1) When the current application determination signal Cd becomes the High level, the heat input correlation value is reset to 0, and the time during which the arc determination signal Ad is at the High level is integrated and calculated as the heat input correlation value.
Process 2) When the current application determination signal Cd becomes High level, the heat input correlation value is reset to 0, and the value of the welding current detection signal Id when the arc determination signal Ad is High level is integrated to obtain the heat input correlation value. calculate.
Process 3) When the current energization determination signal Cd becomes High level, the heat input correlation value is reset to 0, and the product (power) of the welding current detection signal Id and welding voltage detection signal Vd when the arc determination signal Ad is High level. Value) is integrated and calculated as a heat input correlation value.

  The welding power source PS receives a start signal On, a current energization determination signal Cd and the correlation determination signal Sd from a robot controller RC, which will be described later, and outputs a welding voltage Vww and a welding current Iww to output a consumable electrode arc 3a. , A welding wire feed control signal Wc is output to the welding wire feed motor WM, and a filler wire feed control signal Fc is output to the filler wire feed motor FM. . The welding wire feed speed Ws is controlled by the welding wire feed control signal Wc. The filler wire feed speed Fs is controlled by the filler wire feed control signal Fc. The welding power source PS has a constant voltage characteristic. The operation of the welding power source PS will be described in detail with reference to FIG.

  The robot controller RC moves the welding torch WT to the welding start position according to the work program taught in advance and stops it, outputs a start signal On to the welding power source PS, starts welding, and determines the current energization determination described above. When the signal Cd becomes High level, the welding torch WT is moved along the welding line.

  FIG. 2 is a timing chart of each signal in FIG. 1 described above for explaining a welding start method of two-wire welding according to Embodiment 1 of the present invention. FIG. 4A shows the time change of the start signal On, FIG. 2B shows the time change of the welding voltage Vww, FIG. 2C shows the time change of the welding current Iww, and FIG. Shows the time change of the welding wire feed speed Ws, FIG. 5E shows the time change of the filler wire feed speed Fs, and FIG. 4F shows the time change of the current conduction determination signal Cd. (G) shows the time change of the arc discrimination signal Ad, and (H) shows the time change of the correlation discrimination signal Sd. Hereinafter, a description will be given with reference to FIG.

  When the welding torch WT moves to the welding start position and stops at time t1, the activation signal On becomes High level and the welding power source PS is activated as shown in FIG. In response to this, the welding voltage Vww becomes the no-load voltage of the maximum voltage value as shown in FIG. 5B, and the welding wire feed speed Ws is set at a predetermined low speed as shown in FIG. The welding wire 1a starts feeding. As shown in FIG. 6C, the welding current Iww is not energized, and as shown in FIG. 5E, the filler wire feeding speed Fs is 0, and the feeding of the filler wire 1b is stopped. ing.

  At time t2, when the welding wire 1a comes into contact with the base metal 2 by the slow-down feeding described above, the welding current Iww is energized as shown in FIG. 10C, and the current as shown in FIG. The energization determination signal Cd becomes High level. In response to this, as shown in FIG. 4D, the welding wire feeding speed Ws is accelerated to a predetermined steady feeding speed, and the welding torch WT starts moving along the welding line. In the subsequent period, the period from time t2 to t3 is a short circuit period, the period from time t3 to t4 is an arc period, the period from time t4 to t5 is a short circuit period, and the period after time t5 is an arc period. That is, it is a case where two short circuits occur at the start of welding.

  During the short-circuit period from time t2 to t3, as shown in FIG. 5B, the welding voltage Vww is a short-circuit voltage value of approximately 0 V, and as shown in FIG. 5C, the welding current Iww is greater than during the arc period. Becomes a short-circuit current value of a large current value. As shown in FIG. 5G, the arc discrimination signal Ad remains at the low level.

  At time t3, a consumable electrode arc 3a is generated, and during the arc period from time t3 to t4, the welding voltage Vww has an arc voltage value of several tens of volts as shown in FIG. As shown, the welding current Iww is a smaller arc current value than during the short circuit period. As shown in FIG. 5G, the arc discrimination signal Ad is at a high level.

  At time t4, a short circuit occurs again. During the short circuit period from time t4 to t5, the welding voltage Vww becomes a short circuit voltage value of approximately 0 V as shown in FIG. The welding current Iww is a short-circuit current value having a larger current value than during the arc period. As shown in FIG. 5G, the arc discrimination signal Ad is at a low level.

  At time t5, the consumable electrode arc 3a occurs again, and after time t5, the arc period is reached. During this arc period, the welding voltage Vww has an arc voltage value of several tens of volts as shown in FIG. 5B, and the welding current Iww is smaller than that during the short circuit period as shown in FIG. The arc current value of the value. As shown in FIG. 5G, the arc discrimination signal Ad is at a high level.

  The correlation discriminating circuit SD in FIG. 1 performs integration (any one of the above-described processes 1) to 3) for calculating the heat input correlation value from time t2 when the current conduction discrimination signal Cd changes to the high level. Start. However, the integration is stopped during the short-circuit period from time t2 to t3 and the short-circuit period from time t4 to t5, and the integration is continued during the arc period from time t3 to t4 and the arc period after time t5. As a result, when the heat input correlation value reaches a predetermined reference value at time t6, the correlation determination signal Sd changes to a high level as shown in FIG. In response to this, as shown in FIG. 5E, the filler wire feeding speed Fs becomes a predetermined steady feeding speed, and feeding of the filler wire 1b is started. Therefore, the period from time t1 to t6 becomes a transition period at the start of welding. The period after time t6 is a steady period. The steady feeding speed of the filler wire 1b is set to about 20 to 40% of the steady feeding speed of the welding wire 1a.

  At the start of welding, the heat input to the base metal is mainly performed during the arc period and little during the short circuit period. For this reason, as in the prior art, when the feeding of the filler wire is started assuming that the weld pool has grown to an appropriate size at the time when the predetermined period has elapsed since the welding current started to flow, during the predetermined period When a short circuit occurs, the amount of heat input to the base material is insufficient, and the filler wire starts to be fed before the size of the molten pool grows to an appropriate size. As a result, the filler wire cannot be transferred to a stable molten state, and the welding quality at the start of welding has deteriorated. On the other hand, in the present embodiment, it is determined that the weld pool has grown to an appropriate size when the correlation value of heat input to the base material from the start of welding current application reaches a predetermined reference value. Then start feeding filler wire. As the heat input correlation value, 1) a time integral value during the arc generation period, 2) an integral value of the welding current during the arc generation period, or 3) a multiplication value of the welding current and the welding voltage during the arc generation period. It is an integral value. Thereby, even if a short circuit occurs during the transition period at the start of welding, the start of feeding the filler wire is always the time when the amount of heat input to the base material reaches the reference value. For this reason, feeding of the filler wire is started when the molten pool has grown to an appropriate size, and the filler wire is in a stable molten state.

  According to the first embodiment described above, when welding is started, feeding of the welding wire is started. When the welding wire comes into contact with the base material, the welding current is energized. When the heat input correlation value to the material reaches a predetermined reference value, feeding of the filler wire is started. As a result, in this embodiment, even if a short circuit occurs between the welding wire and the base metal during the transition period at the start of welding, the heat input to the base metal reaches the reference value, and the molten pool has an appropriate size. Since the feeding of the filler wire is started at the time of growth, the filler wire can be shifted to a stable molten state, and the welding quality at the welding start portion can be kept good.

DESCRIPTION OF SYMBOLS 1a Welding wire 1b Filler wire 2 Base material 2a Molten pool 3a Consumable electrode arc 4a Feeding tip 4b Feeding tip 5a Welding wire feeding roll 5b Filler wire feeding roll AD Arc discrimination circuit Ad Arc discrimination signal CD Current conduction discrimination circuit Cd Current conduction determination signal Fc Filler wire feed control signal FM Filler wire feed motor Fs Filler wire feed speed ID Welding current detection circuit Id Welding current detection signal Iww Welding current On Start signal PS Welding power supply RC Robot controller SD Correlation Discrimination circuit Sd Correlation discrimination signal VD Welding voltage detection circuit Vd Welding voltage detection signal Vww Welding voltage Wc Welding wire feed control signal WM Welding wire feed motor Ws Welding wire feed speed WT Welding torch

Claims (4)

In the welding start method of two-wire welding, in which an arc is generated between the welding wire and the base material and the filler wire is fed in contact with the latter half of the molten pool formed by the arc,
When welding is started, feeding of the welding wire is started, and when the welding wire comes into contact with the base material, a welding current is energized, and the heat input correlation to the base material from the start of energization of the welding current Start feeding the filler wire when the value reaches a predetermined reference value,
A welding start method of two-wire welding characterized by the above. The heat input correlation value is a time integral value of the arc generation period.
The welding start method for two-wire welding according to claim 1. The heat input correlation value is an integral value of the welding current during the arc generation period.
The welding start method for two-wire welding according to claim 1. The heat input correlation value is an integral value of a multiplication value of the welding current and the welding voltage during the arc generation period.
The welding start method for two-wire welding according to claim 1.

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