JP2010207882A5 - - Google Patents

Description

Arc termination control method for two-electrode arc welding

  The present invention forms a good weld bead in two-electrode arc welding where a consumable electrode and a non-consumable electrode arc are generated using a welding torch having a consumable electrode and a non-consumable electrode disposed within a shield gas nozzle. The present invention relates to an arc termination control method for two-electrode arc welding.

  Two-electrode arc welding that simultaneously generates a consumable electrode arc while feeding a wire as a consumable electrode, and generates a non-consumable electrode arc surrounding the consumable electrode arc using a plasma gas such as Ar, for example. It has been proposed (see, for example, Patent Document 1). This technique of supplying heat to the weld base and supplying molten wire from both consumable and non-consumable electrode arcs is suitable for high efficiency welding where welding is performed at a relatively fast welding speed.

  However, in high-efficiency welding, the faster the welding speed, the more difficult it is to end the welding process appropriately. Inadequate termination will result in defects at the end of the weld bead. Such defects cause a decrease in weld strength. For example, if the molten pool generated during welding solidifies in a concave shape due to the dynamic pressure of the non-consumable electrode arc, it becomes a defect.

  For the welding method using only the consumable electrode arc, several termination processes have been proposed (see, for example, Patent Documents 2 and 3). However, these termination processes are not considered at all when a non-consumable electrode arc is used. For this reason, just applying these to two-electrode arc welding is not sufficient to eliminate the above-mentioned problems.

JP 63-168283 A JP 59-7480 A Japanese Patent Laid-Open No. 9-192832

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide a two-electrode arc welding end control method capable of forming a good weld bead.

  The arc termination control method of two-electrode arc welding provided by the present invention uses a welding torch having a consumable electrode and a non-consumable electrode disposed in a shield gas nozzle for discharging a shield gas, and uses a consumable electrode arc and a non-consumable electrode arc. An arc termination control method of two-electrode arc welding for welding by generating a consumable electrode arc, after a steady welding process in which the welding torch is moved in the welding forward direction while generating a consumable electrode arc and a non-consumable electrode arc The consumable electrode feeding speed for feeding the consumable electrode is set to be smaller than the size in the steady welding process, and the consumable electrode feeding and the consumable electrode arc are stopped. And performing a second welding end process.

  In a preferred embodiment of the present invention, in the first welding end process, the consumable electrode arc voltage for generating the consumable electrode arc is set smaller than the magnitude in the steady welding process.

  In a preferred embodiment of the present invention, in the first welding end process, the non-consumable electrode arc current for generating the non-consumable electrode arc is made smaller than the magnitude in the steady welding process.

  In a preferred embodiment of the present invention, in the second welding end process, the non-consumable electrode arc current for generating the non-consumable electrode arc is smaller than the magnitude in the steady welding process.

  In a preferred embodiment of the present invention, in the second welding end process, the non-consumable electrode arc current for generating the non-consumable electrode arc is larger than the magnitude in the first welding end process. .

  In a preferred embodiment of the present invention, after the consumable electrode arc is stopped, a third welding end process for moving the consumable electrode in a direction opposite to the feeding direction of the consumable electrode in the steady welding process is performed. Do.

  In the arc termination control method for two-electrode arc welding according to the present invention, a molten wire that is a consumable electrode is supplied to the portion that was a molten pool at the end of the steady welding process by the first welding termination process. Thereby, it can prevent that a molten pool solidifies with the concave shape. Further, during this time, since the molten wire is melted by the consumable electrode arc and the non-consumable electrode arc, it is difficult for spatter to occur. Therefore, it is possible to form a weld bead having a good shape while preventing spatter from adhering to the tip of the welding torch and the non-consumable electrode, and the welding strength can be increased.

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

It is a system configuration figure showing an example of a welding device used for an arc end control method of two-electrode arc welding concerning the present invention. It is a timing chart which shows an example of the arc end control method of 2 electrode arc welding concerning the present invention. It is a timing chart which shows the other example of the arc completion | finish control method of the two-electrode arc welding which concerns on this invention.

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

  FIG. 1 shows an example of a welding apparatus used in an arc termination control method for two-electrode arc welding according to the present invention. The welding apparatus A of this embodiment includes a welding torch B, a GMA welding power source (consumable electrode arc welding power source) PSM, and a plasma arc welding power source (non-consumable electrode arc welding power source) PSP. The welding torch B has a structure in which a plasma nozzle 3, a plasma electrode (non-consumable electrode) 2, and a contact tip 1 are arranged on a concentric axis in a shield gas nozzle 4. From the gap between the shield gas nozzle 4 and the plasma nozzle 3, for example, a shield gas Gs such as Ar is supplied. A plasma gas Gp such as Ar is supplied between the plasma nozzle 3 and the plasma electrode 2. A center gas Gc such as Ar is supplied between the plasma electrode 2 and the contact chip 1.

  A wire W as a consumable electrode is fed from a through hole provided in the contact chip 1. The contact chip 1 is electrically connected to the wire W. The wire W is fed by a feed roller 5 using the motor M as a drive source. The plasma electrode 2 is made of, for example, Cu or a Cu alloy, and is indirectly water-cooled by cooling water passing through a path outside the figure. The plasma nozzle 3 is made of, for example, Cu or a Cu alloy, and is directly water-cooled by forming a channel through which cooling water passes. The welding torch B is normally moved with respect to the welding base material P while being held by a robot (not shown).

The GMA welding power source PSM is a power source for flowing a GMA welding current Iwm by applying a GMA welding voltage Vwm between the wire W and the welding base material P via the contact tip 1. A voltage setting signal Vr is sent from the voltage setting circuit VR to the GMA welding power source PSM. Since the GMA welding power source PSM is a power source having a constant voltage characteristic, the GMA welding voltage Vwm is controlled to the value of the voltage setting signal Vr. Further, a welding start signal St is sent from the welding start circuit ST, and a welding end signal Cr is sent from the welding end circuit CR to the GMA welding power source PSM. A feed control signal Fc is sent to the motor M from the GMA welding power source PSM. When GMA welding voltage Vwm is applied from GMA welding power source PSM, the wire W is a plus side.

The plasma arc welding power source PSP is a power source for flowing a plasma arc welding current Iwp by applying a plasma arc welding voltage Vwp between the plasma electrode 2 and the welding base material P. A current setting signal Ir is sent from the current setting circuit IR to the plasma arc welding power source PSP. Since the plasma arc welding power source PSP is a power source having a constant current characteristic, the plasma arc welding power source PSP is controlled to the value of the current setting signal Ir. A welding start signal St is sent from the welding start circuit ST and a welding end signal Cr is sent from the welding end circuit CR to the plasma arc welding power source PSP. When the plasma arc welding voltage Vwp is applied from the plasma arc welding power source PSP, the plasma electrode 2 is set to the + side.

  Next, an example of the arc termination control method of the two-electrode arc welding according to the present invention will be described below with reference to FIG. The two-electrode arc welding of this embodiment is classified into high-efficiency welding in which the feeding speed of the wire W in the steady welding process is, for example, about 12.5 to 15 m / min.

When the welding start signal St is in the high state, the steady welding is generally performed after a transitional welding start process. In the steady welding process, the wire feed speed Fw is set to the steady wire feed speed Fwn, the GMA welding voltage Vwm is set to the steady GMA welding voltage Vwmn, and the plasma arc welding current Iwp is set to the steady plasma arc welding current Iwpn. . Further, the center gas Gc, the plasma gas Gp, and the shield gas Gs are each supplied at a constant flow rate. The welding torch B is moved by, for example, a robot (not shown). While the steady welding process is performed, the GMA welding current Iwm flows at the magnitude of the steady GMA welding current Iwmn determined by the steady wire feed speed Fwm. Further, the plasma arc welding voltage Vwp is the steady plasma arc welding voltage Vwpn necessary for flowing the steady plasma arc welding current Iwpn. Thus, the consumable electrode arc 6a and the plasma arc 6b are generated with the set strength.

  In the steady welding process, the welding target portion of the welding base material P is melted by the heat supplied from the consumable electrode arc 6a and the plasma arc 6b. The melted wire W is supplied to the melted portion. Thereby, what is called a molten pool is formed. Due to the dynamic pressure of the plasma arc 6b and the gas pressure of the shield gas Gs, the molten pool has a partially recessed shape. Due to the movement of the welding torch B, the molten pool moves to a region where the dynamic pressure of the plasma arc 6b and the gas pressure of the shield gas Gs do not reach. Then, when the surface tension of the molten pool acts, the concave shape of the molten pool is eliminated. As a result, the weld bead formed by solidifying the molten pool generally has a convex shape. Thereby, a weld bead is formed in the path along which the welding torch B has moved.

  When the regular welding is finished, the welding start signal St is in a low state at time t1, and the welding end signal Cr is in a high state. And between time t1 and time t5, welding torch B stops and the 1st-3rd welding end processing is performed.

  First, a first welding end process is performed between time t1 and time t2. In the first welding end process, the wire feed speed Fw is set to the end wire feed speed Fwe, the GMA welding voltage Vwm is set to the end GMA welding voltage Vwme, and the GMA welding current Iwm is determined by the end wire feed speed Fwe. The end GMA welding current Iwme is obtained. Further, the plasma arc welding current Iwp is set to the end plasma arc welding current Iwpe, and the plasma arc welding voltage Vwp becomes the end plasma arc welding voltage Vwpe.

  End wire feed speed Fwe and end GMA welding voltage Vwme are both smaller values than steady wire feed speed Fwn and steady GMA welding voltage Vwmn. Thereby, the end GMA welding current Iwme has a value smaller than the steady GMA welding current Iwmn. The size of the consumable electrode arc 6a generated at this time is smaller than the size of the consumable electrode arc 6a in the steady welding process.

  The magnitude of the end plasma arc welding current Iwpe is set smaller than the magnitude of the steady plasma arc welding current Iwpn. The plasma arc 6b generated at this time is weaker than the plasma arc 6b in the steady welding process.

At time t2, which is the end of the first welding end process, the wire feed speed Fw and the GMA welding voltage Vwm are set to 0, and the GMA welding current Iwm becomes 0. In this case, the consumable electrode arc 6a is extinguished.

  In the first welding end process, the melted wire W is supplied at the end wire supply speed Fwe to the place where the welding torch B was present at the time t1 in the welding base material P. This portion is a portion that is a recessed molten pool at the final point of the steady welding process. This portion is a portion that is not completely subjected to the steady welding process, and may solidify in a concave shape. In the welding end process, an appropriate amount of wire W is supplied to this portion.

  A third welding end process is performed between time t2 and time t3. In the third welding end process, the wire W is rewound. Between time t2 and time t3, the wire supply speed Fw is set to a negative value, and the wire W advances in the direction opposite to the feeding direction. At time t3, the tip of the wire W is located between the tip of the contact tip 1 and the tip of the plasma electrode 2. In addition, between time t2 and time t3, plasma arc welding current Iwp remains set to end plasma arc welding current Iwpe.

A second welding end process is performed between time t3 and time t4. In the second welding end process, the wire feed speed Fw, the GMA welding voltage Vwm , and the GMA welding current Iwm are all zero. On the other hand, plasma arc welding current Iwp remains set to end plasma arc welding current Iwpe.

At time t4, which is the end of the second welding end process, the plasma arc welding current Iwp is also set to 0, and the plasma arc welding voltage Vmp is also set to 0. At this time, the plasma arc 6b also extinguished.

  In the second welding end process, since the wire feed speed Fw is 0, the wire W is not newly supplied to the molten pool. In the second welding end process, the plasma arc 6b is used to smooth the portion where the molten pool has been formed.

  Further, between time t4 and time t5, the wire W is moved in the feeding direction with the wire supply speed Fw set to a positive value. At time t5, the tip of the wire W is positioned between the welding torch B and the welding base material P. At this time t5, the welding end signal Cr is in a low state, and welding by the welding apparatus A is completely completed.

  Next, the operation of the arc termination control method for two-electrode arc welding according to the present invention will be described.

  According to the present embodiment, the wire W is supplied from the time t1 to the time t2 to the portion that was a depressed molten pool at the end of the steady welding, and the dent is eliminated. Further, during the period from time t3 to time t4, the portion that was the molten pool is smoothed using the plasma arc 6b. For this reason, there is no possibility that not only a weld bead portion formed by steady welding but also an inappropriately recessed portion is formed until reaching the end of the weld bead. Therefore, a good weld bead can be formed over the entire region, and the welding strength can be improved.

  Further, according to the present embodiment, since both the consumable electrode arc 6a and the plasma arc 6b are generated in the first welding end process, it is possible to quickly melt a necessary amount of the wire W. . For this reason, it is possible to suppress the amount of generated spatter. Therefore, it is difficult for spatter to adhere to the inside of the welding torch B. Furthermore, since sputtering hardly adheres to the plasma electrode 2, it is possible to maintain good ignition performance of the plasma arc 6 b at the start of the arc, and a uniform arc distribution can be obtained.

  Furthermore, according to the present embodiment, since the second welding end process is performed after the wire W is stored in the welding torch B, the wire W is heated inappropriately during the second welding end process. It is possible to prevent this. For this reason, the sharp shape is maintained without melting the tip of the wire W during the second welding end process. Further, at time t5, the tip of the wire W is returned between the welding torch B and the welding base material P. Therefore, according to the arc end control method of the above two-electrode arc welding, it is easy to start the next arc.

  FIG. 3 shows another embodiment of the present invention. In these drawings, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment.

  FIG. 3 shows a second embodiment of the arc termination control method for two-electrode arc welding according to the present invention. In FIG. 3, the same or similar elements as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment. In the present embodiment, the value of the plasma arc welding current Iwp in the second welding end process is set to be smaller than the steady plasma arc welding current Iwpn and larger than the end plasma arc welding current Iwpe. For this reason, the value of the plasma arc welding voltage Vwp in the second welding termination process is smaller than the steady plasma arc welding voltage Vwpn and larger than the termination plasma arc welding voltage Vwpe.

  According to this embodiment, it is possible to reduce the time required for the second welding end process.

  The arc termination control method for two-electrode arc welding according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the arc termination control method for two-electrode arc welding according to the present invention can be varied in design in various ways.

A Welding device B Welding torch CR Welding end circuit Cr Welding end signal Fc Feeding control signal Fw Feeding speed Iwm GMA welding current (consumable electrode arc welding current)
Iwp Plasma arc welding current (non-consumable electrode arc welding current)
P Welding base material PSM GMA welding power source (consumable electrode arc welding power source)
PSP plasma arc welding power source (non-consumable electrode arc welding power source)
ST Welding start circuit St Welding start signal Vwm GMA welding voltage (consumable electrode arc welding voltage)
Vwp Plasma arc welding voltage (non-consumable electrode arc welding voltage)
W wire (consumable electrode)
1 Contact chip 2 Plasma electrode (non-consumable electrode)
3 plasma nozzle 4 shield gas nozzle 5 feed rollers 6a consumable electrode arc 6b plasma arc (non-consumable electrode arc)

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