Non-consumable electrode arc welding method

Abstract

To achieve high deposition of a filler wire in a non-consumable electrode arc welding method with use of the filler wire.SOLUTION: In a non-consumable electrode arc welding method that generates arc 3 between a non-consumable electrode 1 and a base material 2 to form a molten pool 2, and feeds a filler wire 6 to the molten pool 2 and welds the same, the filler wire 6 is reversely fed to form droplets by the arc 3, and is fed forward to short-circuit transfer the droplets to the molten pool 2. When the filler wire 6 and the molten pool 2 are not short-circuited, switching to forward feeding is started, and when both are short-circuited, switching to reverse feeding is started.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a non-consumable electrode arc welding method in which an arc is generated between a non-consumable electrode and a base metal to form a molten pool, and a filler wire is fed into the molten pool for welding. [Background technology]

[0002] 2. Description of the Related Art A commonly used arc welding method involves generating an arc between an electrode and a base metal to form a molten pool, and feeding a filler wire into the molten pool to perform welding.

[0003] In the invention of Patent Document 1, in a consumable electrode arc welding method in which an arc is generated between a consumable electrode and a base metal to form a molten pool and a filler wire is fed into the molten pool for welding, the insertion position of the filler wire into the molten pool is weaved in the forward and backward directions of the welding direction, and the feed speed of the filler wire is changed in synchronization with the weaving. This makes it possible to stabilize the molten state even if the filler wire feed speed is increased, thereby achieving high welding quality. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5785812 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional arc welding method using a filler wire, the insertion position of the filler wire is weaved in the forward and backward directions of the welding direction in order to increase the adhesion of the filler wire, which requires a weaving mechanism in the filler wire feeder, resulting in a problem of a complex structure and high cost.

[0006] Therefore, an object of the present invention is to achieve high deposition of filler wire in a non-consumable electrode arc welding method using a filler wire by using a general filler wire feeder without adding any special mechanism. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the invention of claim 1 comprises: A non-consumable electrode arc welding method in which an arc is generated between a non-consumable electrode and a base metal to form a molten pool, and a filler wire is fed into the molten pool to weld, The filler wire is fed in a reverse direction to form a molten droplet by the arc, and then fed in a forward direction to short-circuit the molten droplet and transfer it to the molten pool. The present invention relates to a non-consumable electrode arc welding method.

[0008] The invention of claim 2 is as follows: When a non-short circuit is formed between the filler wire and the molten pool, the feed is switched to the forward feed, and when a short circuit is formed between the filler wire and the molten pool, the feed is switched to the reverse feed. 2. The non-consumable electrode arc welding method according to claim 1,

[0009] The invention of claim 3 is as follows: a short-circuit discrimination voltage is applied between the filler wire and the molten pool to discriminate between the non-short-circuit state and the short-circuit state; 3. The non-consumable electrode arc welding method according to claim 2, wherein

[0010] The invention of claim 4 is as follows: When a predetermined backward transport period has elapsed, switching to the forward transport is started, and when a predetermined forward transport period has elapsed, switching to the backward transport is started. 2. The non-consumable electrode arc welding method according to claim 1, Effect of the Invention

[0011] According to the non-consumable electrode arc welding method using a filler wire according to the present invention, high deposition rate of the filler wire can be achieved using a general filler wire feeder without adding any special mechanism. [Brief description of the drawings]

[0012] [Figure 1] 1 is a block diagram of a welding apparatus for carrying out a non-consumable electrode arc welding method according to an embodiment of the present invention. [Diagram 2] 2 is a timing chart of each signal in the welding device of FIG. 1 illustrating a non-consumable electrode arc welding method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0014] Fig. 1 is a block diagram of a welding device for carrying out a non-consumable electrode arc welding method according to an embodiment of the present invention. In this figure, an arc 3 between a non-consumable electrode 1 and a base material 2 is a TIG arc. The arc 3 may be a plasma arc. Each block will be described below with reference to the figure.

[0015] The power supply main circuit PM receives an input of a commercial power supply (not shown) such as three-phase 200V, performs output control by inverter control in accordance with a drive signal Dv described below, and outputs a welding voltage Vw and welding current Iw for generating an arc 3. Although not shown, this power supply main circuit PM includes a primary rectifier circuit that rectifies the commercial power supply, a capacitor that smoothes the rectified DC, an inverter circuit that converts the smoothed DC into high-frequency AC in accordance with the drive signal Dv, a high-frequency transformer that steps down the high-frequency AC to an appropriate voltage value for generating the arc 3, a secondary rectifier circuit that rectifies the stepped-down high-frequency AC, and a reactor that smoothes the rectified DC.

[0016] The short-circuit discrimination voltage application circuit VS is configured with a constant voltage source (not shown) and a resistor (not shown) connected in series, and is connected between the filler wire 6 and the base material 2. The value of this constant voltage source is the short-circuit discrimination voltage Vs. This short-circuit discrimination voltage Vs is set to a value at which no arc occurs even if the filler wire 6 is in a non-short-circuited state, and is set to about 1 to 8 V. For example, the short-circuit discrimination voltage Vs is set to 5 V and the resistor is set to 50 Ω. If the voltage between the filler wire 6 and the base material 2 is represented as the filler wire voltage Vf, when the filler wire 6 and the base material 2 are in a non-short-circuited state, the filler wire voltage Vf is 5 V, and when they are in a short-circuited state, Vf is 0 V. When they are in a short-circuited state, a current of 0.1 A flows through the filler wire 6.

[0017] An arc 3 is generated between a non-consumable electrode 1 attached to a welding torch 4 and a base metal 2, a welding voltage Vw is applied, and a welding current Iw flows. A tungsten electrode is used for the non-consumable electrode 1. The non-consumable electrode 1 becomes the negative electrode and the base metal 2 becomes the negative electrode polarity.

[0018] The filler wire 6 is fed through the liner 7 by the rotation of the feed roll 5 coupled to the feeder FM. A short-circuit discrimination voltage Vs is supplied to the filler wire 6 from the short-circuit discrimination voltage application circuit VS via a power feed tip (not shown). The filler wire 6 is melted by heat from the arc 3. In the figure, the filler wire 6 is fed to the arc 3 from the front in the welding direction. The filler wire 6 may also be fed to the arc 3 from the rear in the welding direction.

[0019] The current detection circuit ID detects the welding current Iw and outputs a current detection signal Id. The current setting circuit IR outputs a predetermined current setting signal Ir. The current error amplifier circuit EI receives the current setting signal Ir and the current detection signal Id, amplifies the error between the two signals, and outputs a current error amplification signal Ei.

[0020] The drive circuit DV receives the current error amplified signal Ei as an input, performs PWM modulation control based on the current error amplified signal Ei, and outputs a drive signal Dv for driving the inverter circuit in the main power supply circuit PM based on the result of the control.

[0021] The filler wire voltage detection circuit VFD detects the filler wire voltage Vf and outputs a filler wire voltage detection signal Vfd. The short circuit determination circuit SD receives the filler wire voltage detection signal Vfd and outputs a short circuit determination signal Sd that goes to low level when the filler wire voltage detection signal Vfd is less than a predetermined short circuit determination value (approximately 3 V) and determines that a short circuit exists, and goes to high level when the filler wire voltage detection signal Vfd is greater than or equal to a predetermined short circuit determination value and determines that a non-short circuit exists.

[0022] The forward transmission peak value setting circuit FSR outputs a predetermined forward transmission peak value setting signal Fsr, and the reverse transmission peak value setting circuit FRR outputs a predetermined reverse transmission peak value setting signal Frr.

[0023] The feed speed setting circuit FR receives the forward feed peak value setting signal Fsr, the reverse feed peak value setting signal Frr, and the short circuit determination signal Sd as inputs, selects either the forward / reverse feed control method 1) or 2) below, processes the method, and outputs the feed speed setting signal Fr. 1) First forward and reverse feeding control method When the short circuit determination signal Sd changes to a high level (non-short circuit state), the value of the forward feed peak value setting signal Fsr is output as the feed speed setting signal Fr, and when the short circuit determination signal Sd changes to a low level (short circuit state), the value of the reverse feed peak value setting signal Frr is output as the feed speed setting signal Fr. 2) Second forward and reverse feeding control method When a predetermined reverse feed period has elapsed, the value of the forward feed peak value setting signal Fsr is output as the feed speed setting signal Fr, and when another predetermined forward feed period has elapsed, the value of the reverse feed peak value setting signal Frr is output as the feed speed setting signal Fr.

[0024] The feed control circuit FC receives the feed speed setting signal Fr as an input and outputs a feed control signal Fc to the feeder FM for feeding the filler wire 6 at a feed speed Fw corresponding to the value of the feed speed setting signal Fr.

[0025] Fig. 2 is a timing chart of each signal in Fig. 1 showing the non-consumable electrode arc welding method according to an embodiment of the present invention. Fig. 2(A) shows the change over time of the welding current Iw passing through the arc, Fig. 2(B) shows the change over time of the filler wire feed speed Fw, and Fig. 2(C) shows the change over time of the short circuit detection signal Sd between the filler wire and the base metal. The operation of each signal will be explained below with reference to the figure.

[0026] As shown in Fig. 1(A), the welding current Iw is controlled to be a constant current based on the value of the current setting signal Ir in Fig. 1. In the figure, the welding current Iw is a constant value, but it may also be a pulse waveform.

[0027] Forward feed means that the filler wire is fed forward in the direction approaching the base material, and reverse feed means that the filler wire is fed backward in the direction away from the base material. When the feed speed Fw is in the forward feed state, it is displayed as a positive value, and when it is in the reverse feed state, it is displayed as a negative value.

[0028] (1) In the case of the first forward / reverse feed control method When the filler wire is fed backward at time t1 to create a non-short circuit between the filler wire and the base metal, the short circuit determination signal Sd changes to a high level (non-short circuit state) as shown in FIG. 1C. In response to this, the filler wire feed speed Fw starts to switch to a positive forward peak value as shown in FIG. 1B. As a result, the feed speed Fw switches to the forward peak value with a slope. The forward peak value is set by the forward peak value setting signal Fsr in FIG. 1 and is, for example, 20 m / min. During this period, the filler wire is melted by the heat from the arc and a molten droplet is formed at the tip.

[0029] When the filler wire and the base metal are short-circuited at time t2 due to the forward feed of the filler wire, the short-circuit detection signal Sd changes to low level (short-circuit state) as shown in FIG. 1C. In response to this, the filler wire feed speed Fw starts to switch to the reverse feed peak value as shown in FIG. 1B. As a result, the feed speed Fw switches to a negative reverse feed peak value with a slope. The reverse feed peak value is set by the reverse feed peak value setting signal Frr in FIG. 1, and is, for example, -15 m / min. During this period, the tip of the filler wire is short-circuited with the molten pool, and the molten pool transfers to the molten pool.

[0030] When the filler wire is returned to a non-shorted state by the reverse feeding of the filler wire, the operation returns to the operation at time t1. Therefore, forward feeding and reverse feeding are periodically repeated in synchronization with the non-shorted state and the shorted state.

[0031] (2) In the case of the second forward / reverse feed control method At time t1, when a predetermined reverse feed period has elapsed, the filler wire feed speed Fw starts to switch to a positive forward feed peak value, as shown in FIG. 1B. As a result, the feed speed Fw switches to a forward feed peak value with a slope. When the filler wire and the base metal are not short-circuited due to the reverse feed of the filler wire near time t1, the short circuit determination signal Sd changes to a high level (non-short circuit state), as shown in FIG. 1C. In the second forward / reverse feed control method, the timing at which the switch to forward feed starts and the timing at which the filler wire and the base metal are not short-circuited are not synchronized. During this period, the filler wire is melted by the heat from the arc, and a molten droplet is formed at the tip.

[0032] At time t2, when the time elapsed from time t1 reaches a predetermined forward feed period, the filler wire feed speed Fw starts to switch to a negative reverse feed peak value, as shown in FIG. 1B. As a result, the feed speed Fw switches to a reverse feed peak value with a slope. When a short circuit occurs between the filler wire and the base metal due to the forward feed of the filler wire near time t2, the short circuit determination signal Sd changes to a low level (short circuit state), as shown in FIG. 1C. In the second forward / reverse feed control method, the timing at which the switch to reverse feed starts and the timing at which the short circuit occurs between the filler wire and the base metal are not synchronized. During this period, the tip of the filler wire is in a short circuit state with the molten pool, and the droplets are transferred to the molten pool.

[0033] When the time elapsed from time t2 reaches the reverse feed period, the operation returns to that at time t1. Therefore, by periodically switching between the reverse feed period and the forward feed period, the non-shorted state and the shorted state are switched.

[0034] The operation and effects of this embodiment will be described below. According to this embodiment, in a non-consumable electrode arc welding method in which an arc is generated between a non-consumable electrode and a base metal to form a molten pool and a filler wire is fed into the molten pool to perform welding, the filler wire is fed in the reverse direction to form droplets by the arc, and the filler wire is fed in the forward direction to short-circuit the droplets to the molten pool. The filler wire is fed in the reverse direction to create a non-short circuit between the filler wire and the molten pool, and the tip of the filler wire is melted by the arc to form droplets. Thereafter, the filler wire is fed in the forward direction to create a short circuit with the molten pool, and the formed droplets are short-circuited. In this embodiment, the formation of droplets and the transfer of the droplets to the molten pool are periodically repeated, thereby stabilizing the molten state of the filler wire and achieving high welding. As a result, in this embodiment, in a non-consumable electrode arc welding method using a filler wire, a general filler wire feeder can be used to achieve high welding of the filler wire without adding any special mechanism.

[0035] More preferably, according to this embodiment, when a non-short circuit state occurs between the filler wire and the molten pool, the feed is switched to the forward feed, and when a short circuit occurs, the feed is switched to the reverse feed. In this way, the formation of droplets in the non-short circuit state and the transfer of the droplets to the molten pool in the short circuit state can be performed periodically, so that the molten state of the filler wire can be stabilized and high welding quality can be achieved.

[0036] More preferably, according to this embodiment, the non-short circuit state and the short circuit state are discriminated by applying a short circuit discrimination voltage between the filler wire and the molten pool. In this way, the non-short circuit state and the short circuit state can be discriminated accurately, and therefore the formation of droplets in the non-short circuit state and the transfer of the droplets to the molten pool in the short circuit state can be made more periodically, so that the molten state of the filler wire can be further stabilized to achieve high welding quality.

[0037] More preferably, according to this embodiment, the wire starts to be switched to the forward feed when a predetermined reverse feed period has elapsed, and starts to be switched to the reverse feed when a predetermined forward feed period has elapsed. In this way, by setting the cycle between the reverse feed period and the forward feed period, the cycle between the formation of droplets in a non-short circuit state and the transfer of the droplets to the molten pool in a short circuit state can be set, so that the molten state of the filler wire can be stabilized to achieve high welding quality. [Explanation of symbols]

[0038] 1 non-consumable electrode 2 Base material (molten pool) 3. Arc 4. Welding torch 5 Feeding roll 6 Filler Wire 7. Liner DV driver circuit Dv drive signal EI Current Error Amplifier Circuit Ei Current error amplification signal FC feed control circuit Fc feed control signal FM feeder FR feed speed setting circuit Fr feed speed setting signal FRR Reverse transmission peak value setting circuit Frr Reverse peak value setting signal FSR forward peak value setting circuit Fsr Positive transmission peak value setting signal Fw Feed speed ID Current Detection Circuit Id Current detection signal IR current setting circuit Ir Current setting signal Iw Welding current PM power supply main circuit SD Short circuit detection circuit Sd Short circuit detection signal Vf Filler wire voltage VFD Filler Wire Voltage Detection Circuit Vfd Filler wire voltage detection signal VS short circuit detection voltage application circuit Vs Short circuit discrimination voltage Vw welding voltage

Claims

1. A non-consumable electrode arc welding method in which an arc is generated between a non-consumable electrode and a base metal to form a molten pool, and a filler wire is fed into the molten pool to weld, The filler wire is fed in a reverse direction to form a molten droplet by the arc, and then fed in a forward direction to short-circuit the molten droplet and transfer it to the molten pool.

4. A non-consumable electrode arc welding method comprising the steps of:

2. When a non-short circuit is formed between the filler wire and the molten pool, the feed is switched to the forward feed, and when a short circuit is formed between the filler wire and the molten pool, the feed is switched to the reverse feed.

2. The non-consumable electrode arc welding method according to claim 1.

3. a short-circuit discrimination voltage is applied between the filler wire and the molten pool to discriminate between the non-short-circuit state and the short-circuit state; 3. The non-consumable electrode arc welding method according to claim 2.

4. When a predetermined backward transport period has elapsed, switching to the forward transport is started, and when a predetermined forward transport period has elapsed, switching to the backward transport is started.

2. The non-consumable electrode arc welding method according to claim 1.

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