KR20120089933A - Non-electrode wire supply method for tandem electro gas arc welding and tandem electro gas arc welding device - Google Patents

Abstract

PURPOSE: A non-electrode wire supply method for tandem electro gas arc welding and a tandem electro gas arc welding device are provided to minimize heat input in tandem electro gas arc welding by supplying a non-electrode wire after arc generated by an electrode wire is stabilized. CONSTITUTION: A non-electrode wire supply method for tandem electro gas arc welding comprises the steps of: measuring current flowing in root and pass electrodes, determining whether to feed non-electrode wires, and feeding a specified amount of root and pass non-electrode wires(W2,W4) according to the measured current value.

Description

Non-Electrode Wire Supply Method for Tandem Electro Gas Arc Welding and Tandem Electro Gas Arc Welding Device}

The present invention relates to a non-electrode wire supply method in a tandem electro gas arc welding device and a welding method in which a non-electrode wire is melted in the arc heat generated by the electrode wire, and specifically, whether a non-electrode wire is supplied by measuring a current value. It is related with the tandem electro gas arc welding apparatus which judges and supplies a non electrode wire, and the non electrode wire supply control method of tandem electro gas arc welding.

The tandem electro gas arc welding method is a welding method that has been developed and applied to increase welding productivity of ultra thick steel having a plate thickness of 50 mm or more, which is required in shipbuilding. In particular, when welding 80mm thick steel by the usual welding method, 80-90 passes of multi-layer welding should be performed for flux cored arc welding, and 2 passes should be welded even for single electro gas arc welding. In shipyards requiring welding productivity, it is preferable to apply tandem electrogas arc welding capable of welding ultra-thick steel in one pass.

However, in order to weld the ultra-thick material of about 80mm in one pass, the high heat input welding of 500kJ / cm or more should be performed. If the heat input of the welding increases, a coarse structure is obtained at the welding part, which inevitably causes the impact toughness to decrease. . Therefore, in order to secure the impact toughness of the welding portion in such high heat input welding, steel for high heat input or high heat input welding material therefor has been developed and applied.

Thus, in order to lower the heat input in tandem electro gas arc welding, a tandem electro gas arc welding apparatus for supplying the non-electrode wires W2 and W4 together to the arcs of the electrode wires W1 and W3 has been proposed.

1 shows such a tandem electro gas arc welding device. Tandem electro gas arc welding mainly uses carbon dioxide (60) as a protective gas, a water-cooled copper alloy 40 is provided on the front surface of the welded material 30, and a fixed backing material 50 is provided on the back, and a wire feeder is provided. An arc is generated between the two electrode wires W1 and W3 and the weld target material 30 supplied by the electrode, and the non-electrode wires W2 and W4 are melted together by the arc heat to melt the molten metal 32. When the molten metal is formed and a predetermined amount is formed, it is a welding method that automatically runs through a traveling device (not shown) equipped with the torch 10, 15, 20, 25 for wire.

However, unlike the electrode wires W1 and W3, since the non-electrode wires W2 and W4 do not directly generate arcs, they are generated by the electrode wires W1 and W3 under the influence of oscillation, slag, and the like of the electrodes. When the arc is unstable, the non-electrode wires W2 and W4 are not melted, and when the non-melt non-electrode wires W2 and W4 are continuously supplied, it leads to the stopping of the welding operation and the failure of the welding apparatus, and eventually, Welding work will be delayed.

The present invention is to solve the above problems, and the supply control method and the tandem electro gas arc welding device of the non-electrode wire supplying the non-electrode wire when the arc generated by the electrode wire is stable to supply the non-electrode wire It aims to provide.

In addition, an object of the present invention is to provide a method for determining that the arc of the electrode wire is stabilized, thereby enabling non-electrode wire feeding control.

In addition, when the arc generated by the electrode wire is stabilized, the non-electrode wire is supplied to increase the amount of metal melting and to increase the welding speed, thereby minimizing the amount of heat input by tandem electrogas arc welding. Moreover, it aims at making fracture toughness and impact toughness of a welded weldment improve.

The present invention provides a non-electrode wire feeding method of the tandem electro gas arc welding and tandem electro gas arc welding apparatus in order to achieve the above object.

The present invention provides a supply control method of a non-electrode wire of a tandem electro gas arc welding apparatus for supplying and welding a non-electrode wire to an arc formed by an electrode wire, the method comprising: measuring a current flowing through a root electrode and a face electrode; It provides a supply control method for the non-electrode wire of the tandem electro gas arc welding apparatus comprising a; supplying step of setting and feeding the supply amount of the root and face non-electrode wire according to the current value obtained in the measuring step.

In addition, the supply control method of the non-electrode wire includes a first determination step of determining whether the non-electrode wire is supplied before the supplying step, and when the supply is determined in the first determination step, the supplying step is a route and The face non-electrode wire can be fed.

At this time, the first determination step, it is preferable to determine whether or not the supply of the current value obtained in the measuring step lasts for 1 to 10 seconds in the 80 to 120% range of the preset current value.

In addition, the supply control method of the non-electrode wire of the tandem electro gas arc welding apparatus of the present invention may further comprise a second determination step of determining whether the supply continues after the supply step.

Here, the second determination step may be to determine whether the current value is less than 20% or more than 180% of the preset current value.

Alternatively, the second determination step may be to determine whether there is a difference between the supply amount set value and the actual supply amount.

The present invention provides a torch for root and face electrode wire for supplying electrode wire; A torch for the root and face non-electrode wires for supplying the non-electrode wires to the arc generated by the electrode wires; An electrode wire and a non-electrode wire feeding device for supplying an electrode wire and a non-electrode wire to the torch for the root and the face electrode wire and the torch for the root and the face non-electrode wire, respectively; A power supply unit supplying power to the root and face electrode wires and including a current sensor measuring a current according to the supplied power; And a control unit connected to the sensor and the wire feeding device, wherein the control unit provides a tandem electro gas arc welding device for controlling the non-electrode wire feeding device according to a current value obtained by the sensor.

In the tandem electro-gas arc welding apparatus of the present invention, a sensor for measuring the actual feeding amount may be mounted in the non-electrode wire feeding device inside the torch for the non-electrode wire.

In addition, the feed amount measuring sensor for measuring the actual supply amount is connected to the control unit, the control unit, if there is a difference between the pre-controlled non-electrode wire supply amount and the actual supply amount measured by the feed amount measurement sensor, Supply of the non-electrode wire can be stopped.

The controller may stop the supply of the non-electrode wire supply apparatus when the current value obtained by the current sensor is less than 20% or more than 180% of a preset current value.

The present invention can provide a supply control method and a tandem electro gas arc welding apparatus for a non-electrode wire for supplying a non-electrode wire only when the arc by the electrode wire is stabilized through the above configuration.

In addition, the present invention provides a method for determining that the arc is stable, thereby enabling non-electrode wire feeding control.

In addition, the present invention supplies the non-electrode wire when the arc is stabilized, thereby minimizing the amount of heat input by tandem electro gas arc welding, thereby improving the fracture toughness and impact toughness of the welded weld.

In particular, when welding the ultra-thick steel materials required in the shipbuilding industry, by providing high-speed low heat welding, not only can the productivity of the shipbuilding industry be improved, but also the welding part performance is increased, thereby enhancing the competitiveness of the shipbuilding industry.

1 is a schematic diagram of a conventional tandem electrogas arc welding apparatus.
2 is a schematic diagram of a tandem electrogas arc welding apparatus of the present invention.
3A is a schematic cross-sectional view of a torch for non-electrode wire of the tandem electro gas arc welding apparatus of the present invention.
3B is a schematic cross-sectional view of a non-electrode wire feeding device of the tandem electro gas arc welding device of the present invention.
FIG. 4A is a graph of voltage and current with time at the beginning of arc formation, and FIG. 4B is a graph showing variation of current with respect to voltage at the beginning of arc formation.
5A is a graph of voltage and current with time during arc stabilization, and FIG. 5B is a graph showing variation of current with respect to voltage during arc stabilization.
6A is a graph of voltage and current with time during arc instability, and FIG. 6B is a graph showing variation of current with respect to voltage during arc instability.
7 is a flowchart of a supply control method of a non-electrode wire of tandem electro gas arc welding according to the present invention.
8 is a partial cross-sectional view of a welded portion welded according to a conventional tandem electro gas arc welding method, and a right side view shows a welded portion welded according to a feeding control method of a non-electrode wire of tandem electro gas arc welding according to the present invention. It is a partial cross section.
9 is a welded metal organization chart welded according to the conventional tandem electro gas arc welding method, and the right side is a welded metal organization welded according to the feeding control method of the non-electrode wire of tandem electro gas arc welding according to the present invention. to be.
10 is a sectional view of the welded portion near the fusion line welded according to the conventional tandem electro gas arc welding method, and the right side is a fusion welded according to the feeding control method for the non-electrode wire of the tandem electro gas arc welding according to the present invention. Weld structure diagram near the line.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the present invention, the root electrode and the root non-electrode mean the electrode and the non-electrode of the backing material 50 side of the electrode and the non-electrode, respectively, and mean the electrode and the non-electrode between the narrow ends of the welded portion of the ultra-thick plate. , The face electrode and the face non-electrode mean an electrode and a non-electrode disposed on the side where the copper filler 40 is installed, respectively, and mean a wide side between the extreme plates of both ends of the welded portion of the ultra thick plate (see FIG. 2).

2 shows a schematic diagram of a tandem electrogas arc welding apparatus of the present invention. The electrode wires W1 and W3 supplied from the torch 10 for the root electrode wire and the torch 20 for the face electrode wire are melted by arc heat and supplied from the torch 15 and 25 for the root and face non-electrode wire. The non-electrode wires W2 and W4 are also melted by the arc generated in the root and face electrode wires W1 and W3.

A water-cooled copper filler metal 40 is provided on the front surface of the to-be-welded material 30, and a fixed backing material 150 is provided on the back surface, and carbon dioxide 60 is supplied to the welding part side as a protective gas.

The torch for the root electrode wire and the torch for the root non-electrode wire (10, 15) and the torch for the face electrode wire and the torch for the face non-electrode wire (20, 25) are integrally oscillated in the weld, and the electrode wires (W1, W3) And the extreme thick plates on both sides with the melt of the non-electrode wires W2 and W4.

The root electrode side is composed of a torch 10 for root electrode wire for supplying the electrode wire W1 and a root electrode contact tip 12 for guiding the root electrode wire to the welded material, and the root non-electrode 115 is a non-electrode. A torch 15 for a root non-electrode wire for supplying the wire W2 and a root electrode contact tip 17 for guiding the root non-electrode wire to a welded material are formed.

The torches 10 and 20 for the root and face electrode wires and the torches 15 and 25 for the root and face non-electrode wires are connected to the welding carriage body 100.

The welding carriage main body 100 is an electrode and a non-electrode wire feeding device for feeding the electrode and the non-electrode wires W1, W2, W3, and W4 to the torch 10, 15, 20, 25 for each electrode and the non-electrode wire ( It is connected to the power supply units 101 and 102 for supplying power to the 120, 121, 122, 123 and the electrode wire (W1, W3).

The electrode wires W1 and W3 are supplied to the torch 10 and 20 for electrode wires through the welding carriage main body 100, and the non-electrode wires W2 and W4 are supplied to the torch 15 and 25 for the non-electrode wires. The power supply is supplied to the electrode wires W1 and W3.

In addition, the power output terminal of the power supply (101, 102) is equipped with a current sensor (111, 112) for checking the current, the electrode and non-electrode wire supply device (120 ~ 143), power supply (101, 102) and current sensor 111 and 112 are connected to the controller 150. A detailed control method of the controller 150 will be described later.

FIG. 3A shows a cross sectional view of the torch 15 and 25 for root and face non-electrode wires, and FIG. 3B shows a cross sectional view of the root and face non-electrode wire feeding devices 121 and 123.

In the present invention, the torches 15 and 25 for the root and face non-electrode wires are rotated together with the non-electrode wires W2 and W4, and encoders 16 and 26 are disposed to measure the amount of rotation thereof. The encoders 16 and 26 are connected to the control unit 150, and the control unit 150 of the non-electrode wires W2 and W4 supplied to the welding unit through the torch 15 and 25 for the root and face non-electrode wires. The payload can be calculated.

In addition, as shown in Figure 3b, the non-electrode wire feeding device 121 is accommodated in the non-electrode wire winding portion 121a, the case 121b, on which the non-electrode wire W2 is wound, and is driven by a driving means (not shown). It is composed of a feeding means 121c rotated to supply the non-electrode wire W2 from the winding part 121a to the discharge part 121d. The driving means is connected to the controller 150, the rotational speed is determined according to the signal of the controller 150.

The tandon electro-gas arc welding device 1 includes a control unit 150 and a sensing unit connected to the control unit 150, a current sensor 111 and 112 and a non-electrode wire that measure currents of the power sources 101 and 102. It includes encoders 16 and 26 for measuring the supply amount, supply means 121c controlled by the controller 150, and power sources 101 and 102, and according to the measured values from the sensing means, the non-electrode The supply and supply amount of the wire (W2, W4) is adjusted, and accordingly the welding heat input can be controlled.

To this end, it is necessary to determine the conditions under which the non-electrode wires W2 and W4 can be supplied and the conditions under which the non-electrode wires W2 and W4 can be supplied, which will be described in detail with reference to FIGS. 4 to 6.

The present invention is a tandem electro gas arc welding apparatus 1 for supplying non-electrode wires W2 and W4 to an arc generated by electrode wires W1 and W3, wherein the non-electrode wires W2 and W4 generate an arc. It is not melted by the arc generated in the electrode wires W1 and W3. Therefore, it is necessary to determine whether the arc formed by the electrode wires W1 and W3 can melt the non-electrode wires W2 and W4.

In this regard, as shown in the graph of the voltage and current with respect to the time of the initial arc formation of FIG. 4A and the graph showing the variation of the current with respect to the voltage of the initial arc formation, as shown in FIG. High current flows through the wires W1 and W3, the wires are heated by Joule heating, and thus the wires are not able to withstand the power supply, so that the arc start fails continuously, and the fluctuation of the voltage and current waveforms is severe. It can be seen that. In addition, as the arc stabilizes, it can be seen that the fluctuation range decreases.

Created by electrode wires W1 and W3, as shown in FIG. 5A, which is a graph of voltage and current over time when the arc is stabilized, and FIG. 5B, which is a graph illustrating the variation of current against voltage when the arc is stabilized. When the arc becomes stable, the current change over time and the voltage change over time are small, and as shown in the graph of the current with respect to voltage, the current value for the voltage converges to one point. That is, it can be confirmed that there is no change in current or voltage when the arc is stable.

FIG. 6A shows a graph of voltage and current over time during arc instability, and FIG. 6B shows a graph showing variation of current with respect to voltage during arc instability. As can be seen in FIGS. 6A and 6B, when the arc is unstable by oscillation and slag of the electrode, that is, when the arc is shaken or the arc is formed small, the fluctuation range is smaller than the initial arc formation. It can be seen that the voltage fluctuates severely.

In particular, the fluctuation range of the wave is larger than the voltage at the current, and therefore, it can be seen that the arc becomes unstable when the measured current value falls below a predetermined current value after the arc is formed.

As can be seen above, depending on the arc initial generation, arc stabilization and arc instability, the graphs of current and voltage over time are each characterized, in particular, arcs which are generated unstable and difficult to melt non-electrode wires. During initial generation and arc instability, it can be seen that the fluctuations of the current and voltage, especially the current, are large. This means that it is possible to determine whether or not the non-electrode wire is supplied by determining whether the arc is stable through the current value.

Such a non-electrode wire feeding control method of the present invention considering the relationship between arc formation and current is summarized in FIG. 7.

Control is started (S100), the current is measured through the current sensor (111, 112) disposed at the power output terminals of the power source (101, 102) (S110), the measurement of this current is continuously performed.

If the current value measured through the current sensors 111 and 112 is greater than or equal to a predetermined value (for example, 100A) (S120), and exceeds a predetermined value (for example, 3 seconds or more) (S130), Since it is possible to determine that the arc is stably generated, the controller 150 supplies the arc electrode non-electrode wires W2 and W4 formed by the electrode wires W1 and W3. The driving means of the supply means 121c can be driven (S140).

In this case, the criterion for stably generating the arc may be determined based on whether the measured current value is maintained for 1 to 10 seconds within the range of 80% to 120% of the set current value. That is, when the set current value is 400A, it may be determined whether the measured current value is maintained for 1 to 10 seconds within the range of 320 to 480 A. If less than 80% or more than 120% of the set current value can be determined that the arc is formed unstable. In addition, if the duration is set to a time shorter than 1 second, there is a risk of arc instability or malfunction of supplying the non-electrode wire before generation. If the duration criterion is set to 10 seconds or more, the non-electrode wire is supplied. Judgment may be delayed and the heat input may increase overall.

If the current value is less than the predetermined value or the predetermined value is not maintained for a predetermined time, since the arc is unstable or the initial state of arc formation, the measurement and determination of the current value is repeated without supplying the non-electrode wires W2 and W4. do.

At this time, the supply amount of the non-electrode wires (W2, W4) can be determined by the current value of the current sensor (111, 112) and the voltage value at the power source (101, 102), and the current value and voltage value When the amount of generated heat is large, more non-electrode wires W2 and W4 may be fed to increase the welding speed to reduce the heat input of the welded portion.

That is, the electric heat energy H (J / cm) generated by arc during welding bead unit length during arc welding follows the following equation, so that the voltage value (V) at the power supply and the current value from the current sensors 111 and 112 When (I) is obtained, the non-electrode wires W2 and W4 can be supplied to increase the overall welding speed v, thereby reducing the amount of heat input.

H (J / cm) = (60 × V × I) / v (where V: voltage, I: current, v: welding speed)

Therefore, the controller 150 may calculate the non-electrode wire feeding amount based on the measured value.

On the other hand, even when the arcs generated on the electrode wires W1 and W3 are unstable, when the non-electrode wires W2 and W4 are supplied, the non-electrode wires W2 and W4 are not melted by the arc and the non-electrode wires ( W2 and W4 collide with the to-be-welded material 30, and the feeding of the non-electrode wires W2 and W4 does not generate | occur | produce despite the drive of the supply apparatus 121c.

This causes a failure of the non-electrode wire feeding apparatuses 121 and 123, resulting in a decrease in the overall welding speed, resulting in an increase in the total heat input. Therefore, it is necessary to stop the supply of the non-electrode wires W2 and W4 in a state in which the non-electrode wires W2 and W4 cannot be melted, that is, in an unstable arc state.

In the unstable state of the arc, the current and voltage waveforms are varied as shown in FIGS. 6A and 6B. Therefore, since the arc is unstable when the fluctuation range of the current value measured by the current sensors 111 and 112 becomes large, it is necessary to stop the supply of the non-electrode wires W2 and W4.

Increasing the fluctuation range of the current value measured by the current sensors 111 and 112 can be determined simply by determining the case where the current value obtained by the current sensors 111 and 112 falls below a certain value, for example, 50 A or less. . Because, when the arc is unstable, the waveform of the current fluctuates up and down around the value of the current when it is stable, so it can be seen that the waveform of the current is fluctuating even if only the current value falls below a certain value (S150). At this time, the supply of the non-electrode wires W2 and W4 can be stopped (S160).

When the current value falls below 20% of the set current value or when the current value exceeds 180% of the set current value, it is preferable to stop the feeding of the non-electrode wires W2 and W4. If it is out of this range, even if the non-electrode wires W2 and W4 are supplied in accordance with the current value, they are not melted in the arc, so it is preferable to stop the supply of the non-electrode wires W2 and W4.

Alternatively, the controller 150 transmits the target amount of the non-electrode wires W2 and W4 calculated by the current value and the voltage value and the sequential sending based on the encoders 16 and 26 of the torch 15 and 25 for the non-electrode wire. In the case where the actual feeding amount based on the encoders 16 and 26 of the non-electrode wire torch 15 and 25 is smaller than the feeding target amount (the preset feeding amount), that is, the feeding means 121c is driven. Even though the front ends of the non-electrode wires W2 and W4 touch the material to be welded 30 and cannot be supplied, the supply of the non-electrode wires W2 and W4 may be stopped (S160).

On the other hand, when the arc is formed stably, it is determined whether the power of the device is turned off (S170), and when the device power is terminated, welding is terminated (S180). If the power is not turned off, it is again determined whether the supply of the non-electrode wires W2 and W4 is stopped (S150), and these two steps (S150 and S170) are repeated.

Example

According to the non-electrode wire feeding control method in the tandem electrogas arc welding apparatus 1 which concerns on this invention, the Example which welded one layer of the ultra-thick steel of 50 mm or more of plate | board thickness is demonstrated. The conventional method is one-layer welding of an ultra thick steel having a plate thickness of 50 mm or more in a conventional tandem electrogas arc welding apparatus without supply control of non-electrode wires.

Table 1 below shows the welding conditions in which one-layer welding of ultra-thick steel with a plate thickness of 60 to 85 mm was performed.

As shown in Table 1, the welding current and voltage applied for the one-layer welding were applied as 400A-44V for the face side and 360A-44V for the root side, as in the conventional welding method.

Accordingly, in the conventional welding method, the welding speed for the one-layer welding is 4.1 cm / min for 60 mm thickness, 3.6 cm / min for 70 mm, 3.2 cm / min for 85 mm, and the welding heat input is 520, respectively. , 587, 654 kJ / cm were applied.

However, in the present invention, the welding speed is 5.7 cm / min for 60 mm thickness, 5.2 cm / min for 70 mm, 4.7 cm / min for 85 mm, and the welding heat input is 370, 406, 450 kJ / cm, respectively. Single layer welding was possible. Therefore, through the control method according to the present invention, high-speed low heat input welding is possible for the same plate thickness as compared with the conventional welding method. That is, when feeding of the non-electrode wires W2 and W4 is possible, by inputting an appropriate amount of the non-electrode wires W2 and W4, the overall welding speed was increased to achieve low heat input of the weld.

8 is a partial cross-sectional view of a welded portion welded according to a conventional tandem electro gas arc welding method, and a right side view shows a welded portion welded according to a feeding control method of a non-electrode wire of tandem electro gas arc welding according to the present invention. It is a partial cross section.

As shown in FIG. 8, in the case of a welded part by a conventional welding method, austenite grains grow in a vicinity of a fusion line heated to a high temperature directly below the melting point, and thus grain structure ferrite grows coarsely from the grain boundary. On the other hand, in the welded tissue welded according to the present invention, austenite grain growth can hardly be observed, and thus coarse grain boundary ferrite growth is not observed, and thus very fine tissue distribution is exhibited.

9 is a welded metal organization chart welded according to the conventional tandem electro gas arc welding method, and the right side is a welded metal organization welded according to the feeding control method of the non-electrode wire of tandem electro gas arc welding according to the present invention. to be.

The weld metal welded according to the conventional method is composed of partially grown grain boundary ferrite and fine intragranular ferrite, but the weld metal welded according to the present invention exhibits little or no traces of grain boundary ferrite and shows the organizational characteristics of the fine grained ferrite. It is showing.

10 is an enlarged view of the welded structure near the fusion line welded according to the conventional tandem electro gas arc welding method, and the right side is according to the feeding control method of the non-electrode wire of tandem electro gas arc welding according to the present invention. An enlarged view of welded tissue near the welded fusion line.

The welded portion welded according to the conventional method is about 150-200 µm in size of austenite grains, grain boundary ferrite grows coarse at grain boundaries, and bainite is mixed locally with ferrite in the mouth.

On the other hand, in the case of welded welds according to the present invention, not only the growth of austenite is not obvious, but the size of the austenite grain is only about 50 μm, indicating that the growth is insignificant. The growth of grain boundary ferrite is not observed and consists mainly of fine polygonal ferrite and pearlite.

The high heat input welding part has a welded portion having a hardness distribution in which the hardness is high in the weld part close to the weld metal, and the hardness decreases closer to the base metal. The area where tissue changes or mechanical properties change due to the heat of welding is called the welding heat affected zone. In the welding zone, a region where the strength of the base material is lost by the heat of the weld is formed at the end of the weld heat affected zone, and this area is called a softened zone. In actual high heat input weld tension test, weld strength below the strength required by the standard is generated.

The weld softening degree is expressed by the above-described weld heat affected zone width and the minimum hardness in the softening region. Table 2 below shows the weld softening degree and the joint tensile strength of the weld welded according to the present invention by comparing the weld softening degree and the joint tensile strength of the weld welded according to the conventional method.

According to the conventional method, the welded portion welded according to the conventional method increases the heat input applied to the plate, and accordingly, the width of the heat affected zone increases to 15, 20, and 23 mm, and the minimum hardness in the softening region is 134, 131, and 128 Hv. Decreases. In the case of welding according to the present invention, the heat input applied increases as the plate thickness increases, but the welding can be performed in one layer with relatively low heat input as compared with the conventional method.

In addition, when welded according to the present invention, the width of the heat affected zone according to the plate thickness is 11, 14, and 16mm, and the minimum hardness is 146, 142, 139 Hv. It can be seen that the minimum hardness indicates a high hardness value.

The characteristics of such a weld can be understood more clearly also in the weld tensile strength. The welding part according to the conventional method has a strength of 510 MPa or less except for the case of 60 mm, while the present invention can secure a high strength of about 520 MPa even at 85 mm.

Table 3 below summarizes the results of measuring the size of the grain near the fusion line where grain growth occurs most significantly in the welded part using an image analyzer. In the conventional welding method, the size of the austenite grains grows as the heat input increases as the thickness increases to 150, 160, and 243 μm. On the other hand, in the case of the welding method of the present invention, it grows with heat input depending on the thickness, but shows a relatively small growth degree of 65, 76, 96 µm in size.

As described above, the miniaturization of the austenite grains enables the miniaturization of the welded structure as described above, and consequently, the low temperature impact toughness of the high heat input welded portion can be improved.

Table 4 below shows the weld low temperature (-20?) Toughness according to the present invention and the conventional method.

In the conventional welding method, the thicker the thickness, the greater the heat input, and the impact toughness of the weld is significantly reduced. In particular, the toughness decreases to 50 J or less in the welding metal and the fusion line, and to 100 J or less in the FL (fusion line) +1 mm. Deterioration is observed.

On the other hand, in the case of the present invention, even the thickest 85mm shows good impact toughness of 50J or more in the weld metal and 100J or more in the weld heat affected zone.

As described above, the control method and the welding apparatus according to the present invention are capable of high-speed welding, as compared to the conventional control method and welding apparatus, not only reduce the amount of heat input, but also increase the impact toughness and tensile strength of the weld heat affected zone. Do.

10, 20: torch for electrode wire 15, 25: torch for non-electrode wire
16, 26: encoder 100: welding carriage body
101, 102: power supply 111, 112: current sensor
120-123: wire supply apparatus 121c: supply means
150:

Claims (10)

In the feeding control method of the non-electrode wire of the tandem electro gas arc welding device,
Measuring a current flowing through the root electrode and the face electrode;
And a supply step of setting and supplying a supply amount of the root and face non-electrode wires according to the current value obtained in the measuring step; supply control method for a non-electrode wire of a tandem electro gas arc welding apparatus comprising a. The method of claim 1,
A first determination step of determining whether the non-electrode wire is supplied,
The supply control method of the non-electrode wire of a tandem electro gas arc welding apparatus characterized by the said supply stage supplying a root and a face non-electrode wire, when supply is determined in the said 1st determination step. The method of claim 2,
The first determination step is to determine to supply the non-electrode wire when the current value obtained in the measuring step is in the range of 80 to 120% of the predetermined current value for 1 to 10 seconds of the tandem electro gas arc welding apparatus, characterized in that Supply control method of non-electrode wire. The method of claim 3, wherein
And a second determining step of determining whether to continue the feeding after the feeding step. The method of claim 4, wherein
The second determination step is to supply the non-electrode wire of the tandem electro gas arc welding apparatus, characterized in that the supply is stopped if the current value measured in the measuring step is less than 20% or more than 180% of the preset current value. Control method. The method of claim 4, wherein
The second determination step, the supply control method of the non-electrode wire of the tandem electro gas arc welding apparatus, characterized in that the supply is stopped to determine if there is a difference between the feed amount set value and the actual feed amount. A torch for root and face electrode wires for supplying electrode wires;
A torch for the root and face non-electrode wires for supplying the non-electrode wires to the arc generated by the electrode wires;
An electrode wire and a non-electrode wire feeding device for supplying an electrode wire and a non-electrode wire to the torch for the root and the face electrode wire and the torch for the root and the face non-electrode wire, respectively;
A power supply unit supplying power to the root and face electrode wires and including a sensor measuring a current according to the supplied power; And
A control unit connected to the sensor and the wire feeding device,
And the control unit controls the non-electrode wire feeding device in accordance with the current value obtained by the sensor. The method of claim 7, wherein
And a non-electrode wire feeding device is equipped with a sensor for measuring the actual feeding amount. The method of claim 8,
The sensor for measuring the actual dispatch amount is connected to the control unit,
The control unit stops the supply of the non-electrode wire when there is a difference between the pre-controlled non-electrode wire feeding amount and the actual feeding amount measured by the sensor for measuring the feeding amount, tandem electro gas arc welding apparatus . The method of claim 8,
And the control unit stops the supply of the non-electrode wire supply device when the current value obtained by the sensor is less than 20% or more than 180% of the preset current value.

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