JP2009106984A - Welding starting method for two wire welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding starting method for two wire welding which can smoothly start two wire welding, and further, can prevent the generation of a welding defect at the starting edge of a weld bead. <P>SOLUTION: Disclosed is a welding starting method for two wire welding where, while generating an arc 2 from a wire WA, it progressed to a welding direction, and further, a filler wire WB is fed from the rear part in the welding direction. The method includes: a step where the filler wire WB is made to approach a welding base material P while being where detection voltage Vt is applied to a space between the filler wire WB and the welding base material P; a step where the approach of the filler wire WB is stopped after the energization of the filler wire WB and the welding base material P; a step where ignition to the arc 2 and the progression of the wire WA and the filler wire WB to the welding direction are started; and a step where the filler wire B is started to be fed toward the welding base material P. By this constitution, the breakage of the filler wire WB and a welding defect at the starting edge of a weld bead Wp can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a welding start method for two-wire welding using a consumable electrode wire and a filler wire.

  Two-wire welding using a consumable electrode wire and a filler wire is known as a welding method suitable for improving the welding speed and improving the appearance of the weld bead (for example, Patent Document 1). FIG. 3 shows an example of conventional two-wire welding. For the two-wire welding shown in the figure, a welding torch including contact tips 91A and 91B is used. The wire WA is supplied through the contact chip 91A. Further, the filler wire WB is supplied to the wire WA from the rear in the welding direction through the contact tip 91B.

  The contact tip 91A is connected to a welding power source (not shown). This welding power source applies a voltage between the contact tip 91A and the welding base material P. As a result, an arc 92 from the wire WA toward the welding base material P is generated. The wire WA is fed from a supply device (not shown) at a speed corresponding to the strength of the arc 92. On the other hand, the filler wire WB is fed by a feeding device (not shown) toward the molten pool Mp generated by the arc 92. Filler wire WB is melted by the heat of molten pool Mp. As a result, the melted wire WA, filler wire WB, and weld base material P are solidified in an alloy state, whereby a weld bead Wp is formed. Such 2-wire welding can prevent the weld bead Wp from becoming extremely thin even if the welding speed is relatively high. Moreover, the external appearance of the weld bead Wp can be made favorable by feeding the filler wire WB without generating an arc.

  However, when starting the two-wire welding, it is necessary to start the welding smoothly so that the starting end of the weld bead Wp does not become a welding defect such as thinning. In particular, it is important to start feeding the filler wire WB accurately to the molten pool Mp that has started to be formed by the ignition of the arc 92. If the feed start timing of the filler wire WB is too early, the filler wire WB collides with the weld base material P on which the molten pool Mp is not formed. This may cause buckling or breakage of the filler wire WB. On the other hand, if the feed start timing of the filler wire WB is too late, there will be a place where the filler wire WB is not supplied despite the formation of the molten pool Mp. The weld bead Wp formed at this location will be extremely thin and cause cracking.

JP 2006-175458 A

  The present invention has been conceived under the circumstances described above, and it is possible to start 2-wire welding smoothly and to prevent a welding defect from occurring at the start end of the weld bead. It is an object of the present invention to provide a welding start method for welding.

  The welding start method of the two-wire welding provided by the present invention advances in the welding direction while generating an arc from the consumable electrode wire by applying a voltage between the consumable electrode wire and the welding object. A welding start method of two-wire welding in which a filler wire is supplied to a consumable electrode wire from behind in the welding direction, and the filler wire is welded in a state where a voltage is applied between the filler wire and a welding object. A step of approaching the object, a step of stopping the approach of the filler wire after the filler wire and the welding object are energized, an arc firing from the consumable electrode wire, the consumable electrode wire, and Starting the progress of the filler wire in the welding direction and feeding the filler wire toward the object to be welded; It is characterized by having the steps of starting, the.

  According to such a configuration, when the filler wire is positioned immediately above the molten pool formed on the welding object by the arc, feeding of the filler wire can be surely started. Therefore, the filler wire buckling and breakage that may occur because the filler wire feed start timing is too early, and the extreme thinning of the weld bead start end due to the filler wire feed start timing being too late. Can be prevented.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

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

  FIG. 1 shows a welding system used in a welding start method for two-wire welding according to the present invention. The welding system A of this embodiment includes a welding torch B, wire feeding devices WFA, WFB, a welding power source PS, and a detection power source PT. The welding system A performs two-wire welding using a wire WA as a consumable electrode wire and a filler wire WB.

  The welding torch B is, for example, a substantially cylindrical nozzle, and is generally attached to a robot (not shown). The welding torch B has contact tips 1A and 1B. The contact chip 1A has a through-hole through which the wire WA can be inserted, and is electrically connected to the wire WA. Contact chip 1B has a through-hole through which filler wire WB can be inserted, and is electrically connected to filler wire WB. In the two-wire welding using the welding torch B, the welding torch B is moved in the welding direction by the robot with the wire WA positioned forward in the welding direction and the filler wire WB positioned rearward in the welding direction.

  The wire feeding devices WFA and WFB are for feeding the wires WA and WB, respectively, and have a drive source such as a motor (not shown). The wire feeders WFA and WFB feed the wire WA and the filler wire WB at a feeding speed that meets the welding conditions in accordance with commands from the welding power source PS and the detection power source PT.

  The welding power source PS is a power source for generating an arc in the wire WA, and includes an output control circuit INV, a welding voltage setting circuit VS, a welding current setting circuit IS, and a feeding speed setting circuit WSA. The output control circuit INV is electrically connected to the contact tip 1A and the welding base material P, and applies a welding voltage Vw between them. When the arc 2 is generated with the welding voltage Vw applied, a welding current Iw flows. A welding voltage setting signal Vs is sent from the welding voltage setting circuit VS to the output control circuit INV. The feeding speed setting circuit WSA is a circuit that sends a feeding speed setting signal Wsa to the wire feeding device WFA.

  The power source PT for detection is a power source for detecting that the filler wire WB has contacted the welding base material P, and includes an output control circuit INVT, a detector ST, and a feed speed setting circuit WSB. The output control circuit INVT is electrically connected to the contact tip 1B and the welding base material P, and applies the detection voltage Vt between them. When the filler wire WB and the welding base material P come into contact with the detection voltage Vt being applied, a detection current It flows. The detector ST is a device that detects that the detection current It flows. When detecting that the detection current It has flowed, the detector ST sends a detection signal St to the welding power source PS. The feeding speed setting circuit WSB is a circuit that sends a feeding speed setting signal Wsb to the wire feeding device WFB.

  Next, an example of a welding start method of two-wire welding using the welding system A will be described below with reference to FIG.

  First, at time t0, a detection voltage Vt is applied between the filler wire WB and the welding base material P. Next, at time t1, feeding of the filler wire WB is started by the wire feeding device WFB as shown in FIG. The feeding speed Fwb at this time is set to a speed slower than that during steady welding.

  Next, when the filler wire WB comes into contact with the welding base material at time t2, as shown in (G2), the detection current It flows and the detection voltage Vt decreases to the short circuit voltage. The detector ST detects that the detection current It has flowed. The wire feeding device WFB stops feeding the filler wire WB by the feeding speed setting signal Wsb from the feeding speed setting circuit WSB. As a result, the filler wire WB is kept in contact with the welding base material P.

  Further, the detection signal St from the detector ST is sent to the output control circuit INV of the welding power source PS. The output control circuit INV stops applying the detection voltage Vt at time t3 after a preset time has elapsed, and applies the welding voltage Vw between the wire WA and the welding base material P. At the same time, the feeding of the wire WA is started as shown in FIG. The feeding speed Fwa at this time is set to a speed slower than that during steady welding.

  When the wire WA approaches the welding base material P, the arc 2 is ignited and the welding current Iw begins to flow at time t4 as shown in FIG. The weld pool Mp starts to be formed in the weld base material P by the arc 2. Further, when the welding current Iw starts to flow, the welding torch B starts to move with respect to the welding base material P at the welding speed F, and the feeding speed Fwa of the wire WA is increased to the speed during steady welding.

  At time t4, the filler wire WB has not yet reached the molten pool Mp. Since the distance between the wire WA and the filler wire WB and the welding speed F are known, the time required from the time t4 until the filler wire WB reaches the molten pool Mp can be calculated. That is, at time t5 when the calculated time has elapsed from time t4, filler wire WB reaches molten pool Mp as shown in FIG. At this timing, the feeding of the wire WB is started again. At this time, for example, the feeding speed Fwb is gradually increased from 0 to the speed during steady welding. By passing through the above welding start method, as shown to the same figure (G6), the transition to the steady state of 2 wire welding is completed, and the weld bead Wp is formed continuously.

  Next, the effect | action of the welding start method of 2 wire welding which concerns on this invention is demonstrated.

  According to the present embodiment, when the filler wire WB is positioned immediately above the molten pool Mp (time t5), the feeding of the filler wire WB can be reliably started. Since the filler wire WB is in contact with the welding base material P from time t3 to time t5, when the feeding of the filler wire WB is started, the filler wire WB is immediately supplied to the molten pool Mp. Therefore, buckling and breakage of the filler wire WB that may occur because the feed start timing of the filler wire WB is too early, or extreme thinning of the weld bead Wp start end due to the feed start timing of the filler wire WB being too late. Can be prevented.

  When two-wire welding is performed on a plurality of locations, the start and end of welding are repeated. It is difficult to control how much the filler wire WB protrudes from the contact tip 1B at the end of welding. For this reason, when the next welding starts, the protruding length of the filler wire WB from the contact tip 1B varies. According to the welding start method of this embodiment, even if the protrusion length of the filler wire WB varies, the feeding of the filler wire WB to the molten pool Mp can be accurately started.

  The welding start method for two-wire welding according to the present invention is not limited to the above-described embodiment. The specific configuration of the welding start method for two-wire welding according to the present invention can be changed in various ways.

It is a system schematic diagram showing an example of a welding system used for a welding start method of 2 wire welding concerning the present invention. It is a timing chart which shows an example of the welding start method of 2 wire welding concerning the present invention. It is principal part sectional drawing which shows an example of the conventional 2 wire welding.

Explanation of symbols

A Welding system B Welding torch F Welding speed Fwa, Fwb Feeding speed INV Output control circuit INVT Output control circuit IS Welding current setting circuit Is Welding current setting signal It Detection current Iw Welding current Mp Weld pool P Weld base material )
PS welding power supply PT detection power supply ST detector detection signal VS welding voltage setting circuit Vs welding voltage setting signal Vt detection voltage Vw welding voltage WA (consumable electrode) wire WB filler wire WFA, WFB wire feeding device Wp welding bead WSA, WSB Feeding speed setting circuit Wsa, Wsb Feeding speed setting signal 1A, 1B Contact tip 2 Arc

Claims (1)

While advancing in the welding direction while generating an arc from the consumable electrode wire by applying a voltage between the consumable electrode wire and the welding object,
A welding start method of two-wire welding for supplying a filler wire from the rear in the welding direction to the consumable electrode wire,
In a state where a voltage is applied between the filler wire and the welding object, the step of approaching the filler wire toward the welding object;
After the filler wire and the welding object are energized, stopping the approach of the filler wire;
Starting the arc firing from the consumable electrode wire and proceeding in the welding direction of the consumable electrode wire and the filler wire;
Starting feeding the filler wire toward the welding object;
The welding start method of two-wire welding characterized by having.

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