KR20160134550A - Electroslag welding method and electroslag welding apparatus - Google Patents

Abstract

The present invention relate to an electroslag welding using a slide type backing plate capable of performing welding while maintaining a predetermined depth of a slag bath, and preventing mechanical features of welding metal by obtaining sound weld penetration. An electroslag welding device (100) comprises: a welding torch (4) having a contact tip (5) applying a current to a welding wire (6); a slide type copper backing plate (2); a driving carriage (16) including the welding torch (4) and the slide type copper backing plate (2); a molten slag bath detector (13); a flux supply device (14); a flux supply control device (15); and a driving carriage control device (17). The flux supply control device (15) controls a supply of flux in order for a length (Ld) of the welding wire (6) from a front end of the contact tip (5) to the molten slab bath (7) to be a predetermined length. The driving carriage control device (17) controls a driving speed of the driving carriage (16) such that a predetermined relation between a reference current value and a welding current (8) is satisfied. The welding is performed while a length (Ls) of the slag bath is maintained at a predetermined depth.

Description

ELECTROSLAG WELDING METHOD AND ELECTROSLAG WELDING APPARATUS FIELD OF THE INVENTION [0001]

One aspect of the present invention relates to an electroslag welding method and an electroslag welding apparatus.

In recent years, in the shipbuilding and industrial machinery fields, the plate thickness tends to increase as the size of each structure increases. Vertical welding of these structures has been performed by high efficiency electrogas arc welding. However, the welding worker has a problem in work environment such as arc radiant heat, fume (Hume) and sputter. Further, shielding performance deteriorates as the plate thickness increases, and other problems such as degradation of the mechanical performance of the welded portion are revealed.

As a solution to these problems, there is an electroslag welding using Joule heat of molten slag as a heat source. In electroslag welding, the exposed arc is not used to melt the wire and the base metal, and heat is generated in the molten slag to melt the wire and the base metal. Therefore, arc radiant heat is not generated, and generation of fumes or spatter is also small. As a result, the working environment is improved. Further, the molten slag shields the weld metal from the atmosphere. Therefore, no shield gas is required. The shielding effect does not deteriorate even when the plate thickness is increased. It is possible to effectively prevent nitrogen or the like existing in the atmosphere from entering the molten metal irrespective of the plate thickness. Therefore, no mechanical deterioration of the weld metal occurs.

On the other hand, in the electrogas arc welding, the molten pool and the penetration state of the base material can be monitored. In the case of the electroslag welding, the melted portion of the molten pool and the molten portion of the base material is covered with molten slag, so that the penetration state of the base material can not be confirmed. It is impossible to confirm whether or not a healthy penetration is obtained unless the bead is observed after the solidified slag covering the bead is destroyed by a hammer or the like.

In addition, sound penetration is important because not only is penetration failure occurring, but also the mechanical properties of the weld metal depend on the degree of penetration. That is, the chemical composition of the weld metal is determined by the chemical composition of the welding wire, the chemical composition of the base metal, and the penetration rate. Since the chemical composition of the welding wire differs from the chemical composition of the base metal, the chemical composition of the weld metal changes when the penetration rate is changed. This affects the mechanical properties of the weld metal. Therefore, it is important to carry out welding while keeping the penetration rate as constant as possible.

Examples of factors that may influence the penetration include a welding current, a welding voltage, and a wire projection length. In addition, an example of a factor is the depth of the slag bath in the case of electroslag welding. Welding current, welding voltage, wire protrusion length, etc. are parameters that can be easily managed. However, it is difficult to measure the slag bath depth, and it is difficult to control the slag bath depth accordingly.

Here, for example, Patent Document 1 discloses a conventional electrogas arc welding apparatus. The oriented electrogas welding apparatus performs upward welding while supplying a flux inlet wire to an improvement (opening) extending in a vertical direction (z) of a substantially vertically erected steel plate. The preferred electrogas welding apparatus includes a balancing and vibrating means. The bogie includes a first electrode, a second electrode, and a driving motor. The tip of the first electrode enters the improvement. The second electrode enters the improvement at a position closer to the opening side of the improvement in the plate thickness direction (x) of the steel plate than the front end of the first electrode. Banks can rise along with improvements. The vibrating means is supported on the carriage. The vibrating means rocks the first and second electrodes in the plate thickness direction (x).

Further, Patent Document 1 discloses the following contents. That is, the molten metal is formed in the improvement as the welding proceeds. Further, molten slag accumulates on the molten metal. The surface of the molten slag rises to reduce the projecting length of the wire projecting from the welding torch. When the current value between the power supply circuit and the vertical plate rises above a predetermined value, a rising instruction is issued to the vehicle. Furthermore, a sliding-type copper backing plate covering the opening of the improvement rises as the welding proceeds. Accordingly, the molten slag in the molten pool is sequentially introduced between the sliding type copper backing plate and the weld bead, and solidified on the weld bead. In this way, molten slag is consumed.

For example, Patent Document 2 discloses a non-consumable nozzle type two-electrode electroslag welding method as a conventional electroslag welding. In the non-consumable nozzle type two-electrode electro-slag welding method, in the improvement formed by being surrounded by the backing plate and the base material, welding is simultaneously performed by the two electrodes. The non-consumable nozzle type two-electrode electrosurgical welding method includes the steps of simultaneously oscillating two-electrode electric power feeding nozzles in the same direction as the arrangement direction of the two electrodes, and stopping the feed nozzles Wc <Wh between the current energy Wm at the time of swinging the feed nozzle, the current energy Wh at the stop at the improvement end, and the current energy Wc at the time of stop at the vicinity of the improvement center portion And driving the feed nozzle by driving it so as to maintain the projecting length of the welding wire sufficiently to set the welding current to the target current value.

Further, Patent Document 2 discloses the following contents. That is, the welding is carried out for the improvement in which the backing plate and the base material are surrounded by the four sides. The flux containing manganese dioxide is introduced at the start of welding so that the slag bath depth during welding is 15 mm.

Japanese Laid-Open Patent Publication No. 1998-118771 Japanese Patent Laid-Open No. 1993-42377

Electro-slag welding has characteristics such that arc radiant heat is not generated and generation of fume and spatter is less than that of electro-arc arc welding. However, in the conventional electroslag welding, the electrode is suspended from the upper side to improve the surroundings surrounded by the steel plate, and the welding is performed. Therefore, since the slag is not consumed, proper slag bath depth can be maintained. However, as the size of each base material increases, workability is deteriorated, and the size of the base material that can be welded is limited depending on the size of each nozzle. Therefore, electroslag welding is generally applied to welding of building steels having a length of several meters, for example. On the other hand, when the backing plate is slid using a bogie, such as an electrogas arc welding, welding can be performed on a larger base metal. In such a case, the welding is not carried out for the improvement in which the steel sheet is surrounded by the four sides. As a result, the slag can flow between the sliding backing plate and the weld bead, and can be consumed.

Therefore, when the slide type backing plate is used for electroslag welding, a flux for supplementing the consumption of slag must be injected from above to keep the slag bath depth as constant as possible in order to ensure sound penetration. Basically, the slag bath can be made constant by applying a considerable amount of flux to the consumed amount. However, if the improvement range is widened, the bead width is widened and the consumption of slag is increased. Further, when the flow of the slag is changed due to the temperature of the backing plate, the consumption amount of the slag also changes. Furthermore, even when the gap between the backing plate and the base material is changed or the welding speed is changed, the consumption amount is changed.

In this way, in the electroslag welding using the slide type backing plate, the consumption amount of the slag is changed due to various factors, and therefore, it is necessary to change the input amount of the flux. However, it is difficult to measure the slag bath depth. Therefore, the welder has no choice but to change the input amount by observation and estimation. Therefore, it depends on skill and insight of the welding worker, and it is extremely difficult to keep the slag bath depth at a predetermined depth to sound the penetration. In addition, changes in penetration not only cause welding defects, but also adversely affect the mechanical properties of the weld metal.

According to the above-described methods disclosed in Patent Document 1 and Patent Document 2, when the electroslag welding using the sliding backing plate is performed, the depth of the slag bath changes and affects the penetration and the mechanical properties of the weld metal. Therefore, although the electroslag welding is excellent in welding workability, it is unfortunately not applicable to welding of a structure having a long weld line.

It is an object of one aspect of the present invention to provide a method of welding a slag backing plate by performing a welding while maintaining a slag bath depth at a predetermined depth in electroslag welding using a slide type backing plate to secure a good penetration and prevent degradation of mechanical properties of the weld metal .

Under such circumstances, one aspect of the present invention is to provide a method of electroslag welding, which is a method of electroslag welding, in which the flux is introduced into the slag bath so that the length of the welding wire from the tip of the contact tip to the slag bath becomes a predetermined length, Adjusting a traveling speed of a traveling vehicle equipped with a welding torch and a sliding type backing plate so that a predetermined relationship between a welding current and a reference current value is satisfied; And performing the welding while performing the welding.

According to another aspect of the present invention, there is provided an electroslag welding apparatus comprising: a welding torch having a contact tip for supplying a welding wire; a sliding type backing plate; a traveling carriage having a welding torch and a slide type backing plate; , A running track control device, a slag bath detector, a flux supply device, and a flux supply control device,

The slag bath detector is configured to detect the slag bath when the slag bath rises from a tip end of the contact tip to a predetermined length position and the flux supply control device detects the length of the welding wire from the tip of the contact tip to the slag bath The supply of the flux is stopped when the slag bath detector detects the slag bath, and when the slag bath detector is not detecting the slag bath, the supply of the flux is performed so as to perform the supply of the flux And the traveling bogie control device is configured to control the traveling speed of the traveling bogie so that a predetermined relationship between the reference current value determined in accordance with the wire feeding speed and the welding current is satisfied and the electroslag welding device is configured to control the traveling speed of the traveling bogie, Welding can be performed while maintaining the depth at a predetermined depth. , It provides the electro slag welding device.

Further, when the welding current becomes larger than the reference current value as a predetermined relation, the traveling car control device increases the traveling speed of the traveling car and decreases the traveling speed of the traveling car when the welding current becomes smaller than the reference current value as a predetermined relationship Or the like.

The slag bath detector may be configured to detect the welding voltage and detect the slag bath when the detecting terminal of the slag bath detector contacts the slag bath.

Further, the slag bath detector may be configured to process the detected welding voltage with a filter having a time constant of 1/2 to 2 times the weaving period to determine whether or not the slag bath is detected .

Further, the detection terminal may be connected to the welding torch.

Further, the slag bath detector may be configured to detect a slag bath based on a decrease in the voltage of the detection terminal when a detection terminal is brought into contact with the slag bath by applying a voltage from a DC power source to a detection terminal of the slag bath detector Lt; / RTI &gt;

Further, the slag bath detector may have a photosensor, and may be configured to detect light from the slag bath and detect the slag bath.

The flux supply device may also be configured to supply flux by a valve driven by a solenoid.

In addition, the flux supply device can be configured to supply flux by a screw driven by a motor.

In addition, the reference current value can be automatically changed based on a predetermined function indicating the relationship between the wire feeding speed and the reference current value when the wire feeding speed is changed.

In addition, the reference current value can be determined depending on the type of the welding wire based on a predetermined function according to the type of the welding wire.

In one aspect of the present invention, in electroslag welding using a sliding backing plate, welding is carried out while maintaining the depth of the slag bath at a predetermined depth, and sound penetration is ensured to prevent deterioration of the mechanical properties of the weld metal have.

1 is a view showing an example of a schematic configuration of an electroslag welding apparatus according to an embodiment of the present invention,
Fig. 2 is a view of the electroslag welding apparatus shown in Fig. 1 viewed from the direction of arrow T,
3A is a diagram showing the correlation between the depth of the molten slag bath, the length of the welding wire, the welding current and the penetration width,
3B is a view showing a correlation between the depth of the molten slag bath, the length of the welding wire, the welding current and the penetration width,
3C is a view showing the relationship between the depth of the molten slag bath, the length of the welding wire, the welding current and the penetration width,
4 is a view showing a structural example of a molten slag bath detector,
5 is a view showing an example of a welding voltage distribution on the surface of a molten slag bath,
6A is a view showing an example of a welding voltage distribution on the surface of a molten slag bath when the welding torch is rocked in the plate thickness direction,
6B is a view showing an example of the welding voltage distribution on the surface of the molten slag bath when the welding torch is oscillated in the plate thickness direction,
6C is a view showing an example of a welding voltage distribution on the surface of the molten slag bath when the welding torch is oscillated in the plate thickness direction,
Fig. 7 is a view showing a configuration example in which a filter circuit is provided in the molten slag bath detecting apparatus shown in Fig. 4,
8 is a view showing an example of a welding voltage waveform when there is no filter circuit,
9 is a diagram showing an example of a welding voltage waveform when a filter circuit is used,
10 is a view for explaining an example of a configuration in which a detection terminal is connected to a welding torch,
11 is a view showing another configuration example of the molten slag bath detector,
12 is a view showing another configuration example of the molten slag bath detector,
13A is a diagram showing a configuration example of a flux supply device,
13B is a diagram showing a configuration example of the flux supply device,
14 is a view showing another configuration example of the flux supply device,
15 is a view showing a comparison result between the case where the slag bath is not controlled and the case where the slag bath is controlled in the present embodiment,
16 is a table for explaining the effect of slag bath depth on welding.

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

<Configuration of welding apparatus>

First, the electroslag welding apparatus 100 according to the present embodiment will be described. Fig. 1 shows an example of a schematic configuration of an electroslag welding apparatus 100 according to the present embodiment. 1, the direction indicated by the arrow Z is referred to as the upward direction in the vertical direction (vertical direction), the direction indicated by the arrow X is referred to as the rightward direction in the plate thickness direction (lateral direction) The direction from the back surface to the front surface is referred to as the forward direction of the horizontal transverse direction Y. [ 2 is a view of the electroslag welding apparatus 100 shown in Fig. 1 viewed from the arrow T. Fig. 2 is a view of the electroslag welding apparatus 100 viewed from above. 2, the welding torch 4, the flux supply device 14, the flux supply control device 15, the traveling carriage 16, and the traveling carriage control device 17, which will be described later, are omitted.

1, the electroslag welding apparatus 100 according to the present embodiment includes a fixed copper backing plate 1, a sliding type copper backing plate 2, a welding torch 4, a molten slag A bath detector 13, a flux supply device 14, a flux supply control device 15, a traveling carriage 16, and a traveling carriage control device 17.

In the electroslag welding apparatus 100, a fixed copper backing plate 1 is disposed on the back side of the improvement, and a sliding type copper backing plate 2 is disposed on the surface side of the improvement. Here, instead of the back side copper backing plate 1, a backing material composed of heat resistant ceramics may be used. The sliding-type copper backing plate 2 on the front side is a copper backing plate sliding in the vertical direction. The slide-type copper backing plate 2 is water-cooled. As the sliding type copper backing plate 2, any substitute of copper may be used.

The welding torch 4 feeds the welding wire 6 by welding current 8 supplied from a welding power source (not shown) to weld the welding base material 3. The welding torch 4 also has a contact tip 5. The contact tip 5 guides the welding wire 6 and supplies a welding current 8 to the welding wire 6.

The molten slag bath detector 13 detects the position of the molten slag bath 7.

The flux supply device 14 injects the flux 12 into the molten slag bath 7. The flux 12 is melted to become molten slag. Therefore, when the flux 12 is introduced, the amount of the molten slag bath 7 is increased.

The flux supply control device 15 controls the operation of the flux supply device 14 to adjust the amount of the flux 12 that is input to the molten slag bath 7.

The traveling cart 16 is provided with a slide type copper backing plate 2, a welding torch 4, a molten slag bath detector 13, a flux supply device 14, a flux supply control device 15, 17), and moves upward (in the direction indicated by the arrow Z). That is, the traveling truck 16 includes a slide type copper backing plate 2, a welding torch 4, a molten slag bath detector 13, a flux supply device 14, a flux supply control device 15, And moves integrally with the device 17. Therefore, their relative positional relationship does not change. Since the traveling carriage 16 ascends, welding can be performed in the upward direction.

The running vehicle control device 17 controls the operation of the traveling carriage 16 by increasing or decreasing the traveling speed of the traveling carriage 16.

The welding wire 6 is fed from the contact tip 5 of the welding torch 4 in an improvement surrounded by the welding base material 3, the copper backing plate 1 and the sliding copper backing plate 2, And then transferred into the molten slag bath 7 formed in the improvement. The welding current 8 flows from the welding wire 6 through the molten slag bath 7 into the molten metal 9. At this time, due to the welding current 8 flowing into the molten slag bath 7 and the resistance of the molten slag bath 7, strip heat is generated and the welding wire 6 and the welding base material 3 are welded Can proceed.

As the welding proceeds, the molten metal 9 is cooled to become the weld metal 10. A portion of the molten slag bath 7 comprises a molten slag layer formed between the copper backing plate 1 and the weld metal 10 and a molten slag layer formed between the slidable copper backing plate 2 and the weld metal 10 do. This molten slag layer is cooled to become a solidified slag 11. In this way, a portion of the molten slag bath 7 becomes a solidified slag 11 covering the bead surface. Therefore, the molten slag bath 7 is consumed as the welding proceeds. Therefore, the depth Ls of the molten slag bath 7 decreases. In order to compensate for the decrease in the molten slag bath 7, the flux 12 which is melted and becomes the molten slag bath 7 needs to be added further.

The amount of the solidified slag 11 covering the bead surface varies in accordance with the width of each bead and the width of improvement in welding. The amount of the solidified slag 11 also varies depending on the degree of adhesion between the copper backing plate 1 and the sliding back plate 2 and the cooling state. Therefore, the amount of the solidified slag 11 is not constant. In order to keep the depth Ls of the molten slag bath 7 constant, it is necessary to change the amount of the flux 12 to be supplied. However, since the depth Ls of the molten slag bath 7 is not known, the depth Ls of the molten slag bath 7 fluctuates when the amount of the flux 12 is not appropriate.

Therefore, in the present embodiment, control is performed to make the depth Ls of the molten slag bath 7 constant. Here, the term "constant" is not limited to the case where the depth Ls of the molten slag bath 7 always becomes one value, and the depth Ls of the molten slag bath 7 is constant But may also include a value within the range. That is, the depth Ls of the molten slag bath 7 is controlled to be maintained at a predetermined depth.

The first requirement for keeping the depth Ls of the molten slag bath 7 constant is as follows. That is, the welding wire length Ld between the tip of the contact tip 5 and the upper surface of the molten slag bath 7 (hereinafter referred to as a dry extension Ld) is controlled to be a predetermined length will be. The second requirement for keeping the depth Ls of the molten slag bath 7 constant is as follows. That is, the traveling bogie control device 17 is controlled so that the predetermined relationship between the predetermined reference current value and the welding current 8 is satisfied, that is, the reference current value and the welding current 8 are equal to each other, And controls the traveling speed of the traveling cart 16.

&Lt; Requirements to keep the depth of the molten slag bath constant >

First, the first requirement for making the depth Ls of the molten slag bath 7 constant will be described.

When the molten slag bath detector 13 is not detecting the molten slag bath 7, that is, when the molten slag bath detector 13 disposed on / on the top of the slide type copper backing plate 2 is in the molten slag bath 7, the flux supply control device 15 controls the flux supply device 14 so as to feed the flux 12. [ On the other hand, when the molten slag bath detector 13 is detecting the molten slag bath 7, that is, when the molten slag bath detector 13 disposed on / on the upper side of the sliding type copper backing plate 2, The flux supply control device 15 controls the flux supply device 14 so as to stop the input of the flux 12. In this case, In this way, the flux supply device 14 adjusts the depth Ls of the molten slag bath 7 by injecting the flux 12 so that the molten slag bath detector 13 detects the molten slag bath 7 .

Here, the welding torch 4, the sliding type copper backing plate 2 and the molten slag bath detector 13 are both mounted on the traveling carriage 16. Even when the traveling carriage 16 moves, their relative positional relationship does not change. Therefore, the distance between the tip of the contact tip 5 and the molten slag bath detector 13 does not change either. When the molten slag bath 7 rises from a tip end of the contact tip 5 to a position of a predetermined length (i.e., the position of the molten slag bath detector 13), the molten slag bath detector 13 detects the molten slag bath 7, (7). The flux supply control device 15 controls the amount of the flux 12 to be supplied so that the molten slag bath 7 is detected by the molten slag bath detector 13. Therefore, the distance between the tip of the contact tip 5 and the upper surface of the molten slag bath 7, i.e., the dry extension Ld, can be controlled to be a predetermined length.

Next, the second requirement for making the depth Ls of the molten slag bath 7 constant will be described.

Figs. 3A to 3C show the correlation between the depth of the molten slag bath 7, the length of the welding wire 6, the welding current 8 and the penetration width, respectively. 3A to 3C, when the depth Ls of the molten slag bath 7 is controlled so as to satisfy the relationship of Ls1 > Ls2 > Ls3 in a state in which the dry extension Ld is controlled to have a predetermined length, The length of the welding wire 6 immersed in the molten slag bath 7 (hereinafter referred to as a wet extension Lw) has a relationship of Lw1> Lw2> Lw3 And the penetration width Lm is changed so as to maintain the relationship of Lm1 < Lm2 < Lm3. On the other hand, letting the value of the welding current 8 be Iw, the relationship between the welding current Iw and the wire feeding speed Vw is expressed by the following equation (1).

[Equation 1]

In Equation (1), K1 to K4 are integers determined based on the diameter, structure and material of the welding wire 6. [

Next, in a state where the welding is performed with the wire feeding speed Vw constant, the flux supply control device 15 sets the length of the dry extension Ld to a predetermined length as shown in the first requirement described above Under the controlled condition, Equation (1) is expressed as Equation (2) below.

&Quot; (2) &quot;

That is, based on Equation (2), the welding current Iw is changed in inverse proportion to the wet extension Lw. When the wet extension Lw becomes large, the welding current Iw becomes small. Further, as described above, since the depth Ls of the molten slag bath 7 is proportional to the wet extension Lw, the welding current Iw when the molten slag bath 7 has the appropriate depth Ls2 is represented by Is set as the reference current value Iw2 in advance. When the welding current Iw is larger than the reference current value Iw2 as the welding progresses, the depth Ls of the molten slag bath 7 becomes smaller than Ls2 and the penetration width Lm becomes larger than Lm2 It is judged to be bigger. Therefore, the traveling lane control device 17 increases the traveling speed of the traveling lane 16. When the traveling speed of the traveling carriage 16 is increased, the wire protruding length Ld + Lw is controlled to be larger, and the welding current Iw is reduced to become the reference current value Iw2. On the other hand, when the welding current Iw is smaller than the reference current value Iw2, it is determined that the depth Ls of the molten slag bath 7 is larger than Ls2 and the penetration width Lm is smaller than Lm2. Therefore, the traveling lane control device 17 reduces the running speed of the traveling lane 16.

Incidentally, at first, the depth Ls of the molten slag bath 7 is adjusted to be Ls2 as a predetermined depth, and then the welding is started. The traveling speed of the traveling cart 16 is determined according to the value of the welding current Iw. As the welding progresses, a part of the molten slag bath 7 becomes solidified slag 11 and is consumed. Therefore, the depth Ls of the molten slag bath 7 decreases. When the molten slag bath detector 13 disposed on / on the top of the slide-type copper backing plate 2 is reduced to such an extent that it does not contact the upper surface of the molten slag bath 7, the flux supply control device 15 controls the flux And controls the flux supply device 14 so as to inject the fluid 12. The flux 14 is injected for a while. Thereafter, the flux supply control device 15 controls the supply of the molten slag bath 7 to the molten slag bath 13 when the molten slag bath detector 13 detects the molten slag bath 7, that is, The flux supply device 14 is controlled so as to stop the input of the flux 12 when the bath detector 13 contacts the upper surface of the molten slag bath 7. Thus, the distance between the tip of the contact tip 5 and the upper surface of the molten slag bath 7, i.e., the dry extension Ld, is controlled to be a predetermined length. On the other hand, the welding current Iw when the molten slag bath depth is appropriate is set as the reference current value Iw2. Therefore, when the dry extension Ld is constantly controlled by the above control, the wet extension Lw can be made constant, and the slag bath depth can also be constant.

In this way, the traveling car control apparatus 17 controls the running speed of the traveling car 16 so that the welding current Iw becomes equal to the reference current value Iw2. Thereby, the control is performed such that the depth Ls of the molten slag bath 7 becomes constant at an appropriate depth Ls2. Therefore, an appropriate penetration width Lm2 can be obtained. In addition, a weld metal having stable mechanical properties can be obtained.

In addition, the reference current value Iw2 is determined as follows. First, in the electroslag welding apparatus 100, when welding is performed with a certain wire feeding speed Vw being constant by using a certain welding wire 6, the dry extension Ld is controlled to have a predetermined length. When the welding is carried out using some kind of welding current Iw, welding is carried out with different wet extensions Lw and different penetration widths Lm. The welding current Iw at which the optimum welding width Lm2 is obtained is determined as the reference current value Iw2 of the wire feeding speed Vw.

Next, the wire feed speed Vw is changed and an optimum reference current value Iw2 is similarly obtained. By repeating this, the reference current value Iw2 can be obtained as a function of the wire feeding speed Vw. This function (a function representing the relationship between the reference current value Iw2 and the wire feeding speed Vw) is stored in advance in the traveling balancing control device 17. [ The reference current value Iw2 can be set in accordance with the wire feeding speed Vw by controlling the reference current value Iw2 to be set using the output of the wire feeding speed setter or the detected value of the wire feeding speed . When the wire feeding speed Vw is changed, the reference current value Iw2 is automatically changed according to the wire feeding speed Vw after the change. Welding can be carried out with the wet extension Lw (or the depth Ls of the molten slag bath 7) which can automatically obtain the optimal penetration.

Further, the welding wire 6 is changed, and the procedure is executed. In this manner, the reference current value Iw2 corresponding to the wire feeding speed Vw can be obtained also for the various welding wires 6. [ Here, the reference current value Iw2 is obtained based on the function of the wire feeding speed Vw, for example, according to the type of the welding wire 6 such as the diameter, structure and material of the welding wire 6 . In other words, the function of the wire feeding speed Vw can be determined according to the type of the welding wire 6, and the reference current value Iw2 can be obtained based on the function of each welding wire 6 type.

<Configuration of Molten Slag Bath Detector>

Next, the construction of the molten slag bath detector 13 will be described in detail. Fig. 4 shows an example of the construction of the molten slag bath detector 13. Fig.

4, the molten slag bath detector 13 in the present embodiment includes a detection terminal 18, a differential amplifier 19, a contact determination reference signal setter 20, and a comparator 21 . The detecting terminal 18 is made of copper, which is a conductive metal. The detection terminal 18 is generally water-cooled. The detecting terminal 18 detects a voltage of a part of the welding voltage when it contacts the molten slag bath 7.

The differential amplifier 19 outputs the difference between both voltages when receiving the voltage of the detecting terminal 18 and the voltage of the sliding type copper backing plate 2 as an input. Since the sliding type copper backing plate 2 is in contact with the welding base material 3, the voltage of the sliding type copper backing plate 2 is the voltage of the base material 3.

The contact determination reference signal setter 20 outputs a voltage as a reference signal. This voltage is substantially half of the voltage detected when the detecting terminal 18 contacts the molten slag bath 7. For example, FIG. 5 shows an example of the welding voltage distribution on the surface of the molten slag bath 7. The detection terminal 18 normally detects a welding voltage of about 6 volts (unit of voltage: V). Therefore, the voltage output as the reference signal is set to about 3V which is half of the detected welding voltage. When the detecting terminal 18 is not in contact with the molten slag bath 7, the welding voltage is not applied to the detecting terminal 18. [ Therefore, the voltage of the detection terminal 18 is 0V.

The comparator 21 receives as input the output signal of the differential amplifier 19 and the reference signal of the contact determination reference signal setter 20. [ When the output signal of the differential amplifier 19 becomes larger than the reference signal of the contact determination reference signal setter 20, the comparator 21 generates a signal that the detection terminal 18 and the molten slag bath 7 have contacted . The generated signal is sent to the flux supply control device 15 so that the flux 12 is supplied and stopped by the flux supply device 14 and the upper surface of the molten slag bath 7 flows from the tip of the contact tip 5 Control is performed so as to be located at a predetermined length. Thereby, the dry extension Ld is maintained at a predetermined length.

6A to 6C show an example of the welding voltage distribution on the surface of the molten slag bath 7 when the welding torch 4 is oscillated in the plate thickness direction. First, the welding voltage distribution shown in Fig. 6B is obtained when the welding wire 6 is at the center of the plate thickness. The welding voltage detected by the detecting terminal 18 is about 6V. At this time, the welding torch 4 is rocked to equalize the penetration in the plate thickness direction. When the welding torch 4 is in the vicinity of the copper backing plate 1, the voltage detected by the detecting terminal 18 disposed in the vicinity of the sliding-type copper backing plate 2 is, as shown in Fig. 6A , Which is about half of 6V. Conversely, when the welding torch 4 reaches the vicinity of the slide-type copper backing plate 2 as shown in Fig. 6C, the welding voltage detected by the detecting terminal 18 becomes as high as about 12V.

Here, when the voltage of the reference signal of the contact determination reference signal setter 20 is set to about 1.5 V, the comparator 21 can correctly determine that the molten slag bath 7 and the detection terminal 18 are in contact with each other have. However, since the value of the reference signal is small, there is a possibility that it may become a hindrance to the correct judgment due to the welding state or external noise.

To prevent such erroneous detection, the molten slag bath detector 13 may include a filter circuit 22 disposed behind the differential amplifier 19, so that the molten slag bath detector 13 is connected to the filter circuit It is possible to judge whether or not the molten slag bath 7 has been detected based on the welding voltage processed by the welding voltage control unit 22. Fig. 7 shows a configuration example in which the filter circuit 22 is provided in the molten slag bath detector 13 shown in Fig. It is preferable that the filter circuit 22 is set as the filter circuit 22 having the time constant about the oscillation cycle of the welding torch 4, that is, about 1/2 to 2 times the cycle.

Fig. 8 shows an example of the welding voltage waveform obtained when the filter circuit 22 is not provided. Fig. 9 shows an example of the welding voltage waveform obtained when the filter circuit 22 is used. Specifically, the waveform shown in Fig. 8 is a detected welding voltage waveform when there is no filter having a sampling period of 250 ms. In addition, the waveform shown in Fig. 9 is a moving average of 27 data, that is, a moving average of the welding voltage waveform of 6.75 seconds (6750 ms). Here, one scale of the vertical axis represents 3.000 V, and one scale of the horizontal axis represents one second (sec). 8 and 9, the oscillation cycle of the welding torch 4 is 8 seconds. Therefore, the welding voltage waveform is equivalent to the oscillation period of the welding torch 4.

When the welding torch 4 is in the vicinity of the copper backing plate 1, the voltage detected by the detecting terminal 18 drops to about 3 V , And when the welding torch 4 is in the vicinity of the slide-type copper backing plate 2, the detected voltage becomes about 12V. Also, the detected welding voltage has a large variation. On the other hand, the welding voltage waveform obtained through the filter is averaged in the range of 9V to 12V. Therefore, when the filter circuit 22 is used, the reference signal of the contact determination can be set to 3V to 6V, whereby the false definition risk can be greatly reduced. Here, an example using a time constant substantially equivalent to the oscillation period is shown, but the effect is also confirmed with a filter having a time constant of about 1/2 to 2 times the oscillation period.

Further, the detection terminal 18 may be connected to the welding torch 4. Fig. 10 is a view for explaining an example of a configuration in which the detection terminal 18 is connected to the welding torch 4. Fig. 10, the configurations of the differential amplifier 19, the contact determination reference signal setter 20, the comparator 21, and the filter circuit 22 are the same as those shown in Fig. 7, 18 are connected to the welding torch 4. When the welding torch 4 is oscillated, the detecting terminal 18 also oscillates together with the welding torch 4. Therefore, the detection terminal 18 is always positioned in the vicinity of the welding wire 6. [ Therefore, referring to the welding voltage distributions shown in Figs. 6A to 6C, when the detecting terminal 18 is in contact with the molten slag bath 7, a welding voltage of about 24 V can be detected. Further, a substantially constant voltage can be detected regardless of the fluctuation of the welding torch 4. Therefore, the risk of being affected by noise or the like is reduced.

&Lt; Other Configuration Example of Melted Slag Bath Detector >

Next, another configuration example of the molten slag bath detector 13 will be described. Fig. 11 and Fig. 12 show other structural examples of the molten slag bath detector 13, respectively.

11, the molten slag bath detector 13 includes a detection terminal 18, a DC power supply 23, a resistor 24, a differential amplifier 19, a filter circuit 22, (20) and a comparator (21). For example, the direct current power source 23 is a power source of about 100 V to 200 V. The output of the DC power supply 23 is connected to the detection terminal 18 through a resistor 24. Here, the value of the resistor 24 is, for example, 20 k? To 500 k ?.

When the detection terminal 18 is not in contact with the molten slag bath 7, no current flows. Therefore, the voltage of the direct-current power supply 23 is substantially applied to the detection terminal 18. [ On the other hand, when the detecting terminal 18 comes into contact with the molten slag bath 7, a current flows from the detecting terminal 18 to the sliding type copper backing plate 2 through the molten slag bath 7. Therefore, the voltage of the direct current power supply 23 is lowered by the resistor 24. The voltage of the detecting terminal 18 drops to a part of the welding voltage, that is, about 3 V to 12 V. These changes are judged by the differential amplifier 19, the filter circuit 22, the contact determination reference signal setter 20 and the comparator 21, and thereafter the molten slag bath 7 is detected. These operations are the same as those in the above-described method, and the description thereof will be omitted.

According to this method, the voltage of the detection terminal 18 when the detection terminal 18 and the molten slag bath 7 are not in contact is 100 V to 200 V. On the other hand, the voltage of the detection terminal 18 when the detection terminal 18 and the molten slag bath 7 are in contact is 3 V to 12 V. Since the difference between both voltages is large, a reliable operation can be expected.

In the example shown in Fig. 12, the molten slag bath detector 13 includes a photoreceptor 25 and a photoreceptor 26 as a photosensor. The light receiver 25 receives light emitted from the surface of the molten slag bath 7. The light receiving device 26 determines when the light amount of the light receiver 25 reaches a certain level. It is possible to adjust the angle of the light receiver 25 and the like so that the dry extension Ld becomes a target predetermined length, on the assumption that the judgment level of the light amount can be predetermined. The determination result is sent to the flux supply control device 15, and the flux 12 is supplied so that the dry extension Ld is kept constant.

In other words, when the light receiving plate 26 determines that the light amount of the light receiver 25 reaches a certain level, the molten slag bath 7 rises from the tip of the contact tip 5 to a position of a predetermined length do. In this case, the dry extension Ld is less than or equal to the predetermined length. Therefore, the flux supply control device 15 controls to stop the input of the flux 12. On the other hand, when the light receiving plate 26 determines that the light amount of the light receiver 25 does not reach a certain level, the molten slag bath 7 rises from the tip of the contact tip 5 to a position of a predetermined length I do not. In this case, the dry extension Ld is larger than the predetermined length. Therefore, the flux supply control device 15 controls the flux 12 to be charged.

<Configuration of flux supply device>

Next, the configuration of the flux supply device 14 will be described in detail. 13A and 13B show examples of the configuration of the flux supply device 14, respectively.

13A, when the solenoid 27 in the flux supply device 14 according to the present embodiment reciprocates as indicated by the arrow 28, the valve 30 Is rotated as indicated by the arrow 31. Thus, the flux supply nozzle 32 is opened and closed. By this operation, the flux 12 of the flux hopper 33 is supplied to the molten slag bath 7.

Here, Fig. 13A shows a state in which the flux supply nozzle 32 is closed. On the other hand, Fig. 13B shows a state in which the flux supply nozzle 32 is open. When the flux supply nozzle 32 is opened, the flux 12 of the flux hopper 33 is supplied to the molten slag bath 7 via the flux supply nozzle 32.

&Lt; Other Configuration Example of Flux Supply Apparatus >

Next, another configuration example of the flux supply device 14 will be described. Fig. 14 shows another configuration example of the flux supply device 14. Fig.

The flux 12 is extruded from the flux hopper 33 by the rotation of the screw 35 driven by the motor 34 in the flux supply device 14 in the example shown in Fig. And is supplied to the molten slag bath 7 via an unused path.

<Examples>

Next, experimental results are shown and an embodiment of the present embodiment will be described. The present embodiment is not limited to these embodiments.

A welding wire 6 having a diameter of 1.6 mm is used in the electroslag welding apparatus 100 shown in Fig. 1 and under the conditions of a wire feed rate of 15.4 m / min, a welding voltage of 42 V and a reference current value of 380 A, Welding was performed at a 20 ° V-improvement of 60 mm plate thickness. Further, the distance between the tip and the base material was set to 45 mm. Further, welding was started at a slag bath depth of 25 mm. Fig. 15 shows a comparison result in the case where the slag bath is not controlled (conventional method) after the electro-slag welding is stabilized and the comparison result in the case where the slag bath is controlled in the present embodiment. Here, the results in this embodiment are shown as examples and the results in the conventional method are shown as comparative examples.

Fig. 15 shows a distance after the electro-slag welding is stabilized and shows the distance at which the traveling carriage 16 has risen, and shows evaluation results of "arc generation", "surface bead width" and "penetration" in each distance. In the "arc generation ", it is referred to as" B " In the case of "penetration", it is referred to as "B" in the case of poor penetration and "A" in the case of no penetration failure. According to the results shown in Fig. 15, it can be seen that, in the case of controlling the molten slag bath 7, the penetration depth is substantially constant, and the surface bead width is not largely changed.

Welding is performed at the wire feeding speed using the electroslag welding apparatus 100 according to the present embodiment, and the results of welding when the slag bath depth is changed will be described. 16 is a table for explaining the influence of the slag bath depth on the welding. Fig. 16 shows evaluation results of "arc generation", "surface bead width", "penetration" and "toughness" in the respective slag bath depths. In the case of "toughness", it is referred to as "A" when the temperature is -20 ° C. and the "toughness" is 39 Joules or more and "B" when the toughness is less than 39J. According to the results shown in Fig. 16, it can be seen that the appropriate slag bath depth in this case is 20 mm to 60 mm. Only one example is shown here. However, the workability changes depending on the type of flux, the type of wire and the welding voltage actually used in welding, and the proper slag bath depth also changes.

In the present embodiment, the electroslag welding apparatus 100 performs welding using one electrode. However, the electroslag welding apparatus 100 is not limited to such a configuration, It can also be executed.

Although the embodiments of the present invention have been described above with reference to the embodiments, the technical scope of the present invention is not limited to the above embodiments. It will be apparent to those skilled in the art that various modifications and alternatives to the present invention may be made without departing from the spirit and scope of the invention.

3: welding substrate, 4: welding torch, 5: contact tip, 6: welding wire, 7: molten slag bath, 8: welding current, 9: molten metal, 1: copper backing plate, 2: slide type copper backing plate, 15: Flux supply control device, 16: Driving bogie, 17: Driving bogie control device, 18: Detection terminal, 10: Welding metal, 11: Solidified slag, 12: Flux, 13: Melting slag bath detector A differential amplifier is provided with a differential amplifier and a contact determination reference signal setting device is provided with a comparator having a filter circuit connected to a DC power source. 32: flux supply nozzle, 33: flux hopper, 34: motor, 35: screw, 100: electroslag welding apparatus

Claims (12)

In an electroslag welding method,
Supplying the flux to the slag bath so that the length of the welding wire from the tip of the contact tip to the slag bath is a predetermined length in the electroslag welding,
Adjusting the traveling speed of the traveling vehicle equipped with the welding torch and the sliding backing plate so that a predetermined relationship between the reference current value and the welding current is satisfied,
And performing the welding while maintaining the slag bath depth at a predetermined depth
Electroslag welding method. In an electroslag welding apparatus,
A welding torch having a contact tip for feeding the welding wire,
A slide type backing plate,
A traveling truck having the welding torch and the sliding backing plate,
A traveling car control device,
A slag bath detector,
A flux supply device,
A flux supply control device,
Wherein the slag bath detector is configured to detect a slag bath when the slag bath rises from a tip end of the contact tip to a predetermined length position,
The flux supply control device stops supply of the flux when the slag bath detector detects the slag bath so that the length of the welding wire from the tip of the contact tip to the slag bath becomes the predetermined length, And to control the flux supply device to execute the supply of flux when the slag bath detector is not detecting the slag bath,
The traveling bogie control device is configured to control the traveling speed of the traveling bogie so that a predetermined relationship between the reference current value determined according to the wire feeding speed and the welding current is satisfied,
The electroslag welding apparatus is capable of performing welding while maintaining the slag bath depth at a predetermined depth
Electro slag welding equipment. 3. The method of claim 2,
Wherein the traveling bogie control device increases the traveling speed of the traveling bogie when the welding current becomes larger than the reference current value as the predetermined relationship and when the welding current becomes smaller than the reference current value as the predetermined relationship, So as to control the traveling speed of the bogie
Electro slag welding equipment. 3. The method of claim 2,
The slag bath detector detects the welding voltage when the detection terminal of the slag bath detector contacts the slag bath and detects the slag bath
Electro slag welding equipment. 5. The method of claim 4,
The slag bath detector is configured to process the detected welding voltage by a filter having a time constant of 1/2 to 2 times the weaving cycle to determine whether or not the slag bath is detected
Electro slag welding equipment. 5. The method of claim 4,
And the detection terminal is connected to the welding torch
Electro slag welding equipment. 3. The method of claim 2,
Wherein the slag bath detector is configured to apply a slag bath to the detection terminal of the slag bath detector by applying a voltage from a DC power source through a resistor so that when the detection terminal contacts the slag bath, configured to detect
Electro slag welding equipment. 3. The method of claim 2,
The slag bath detector has a photosensor, and is configured to detect the slag bath by detecting light from the slag bath
Electro slag welding equipment. 3. The method of claim 2,
The flux supply device is configured to supply flux by means of a valve driven by a solenoid
Electro slag welding equipment. 3. The method of claim 2,
The flux supply device is configured to supply flux by a screw driven by a motor
Electro slag welding equipment. 3. The method of claim 2,
The reference current value is automatically changed based on a predetermined function indicating a relationship between the wire feeding speed and the reference current value when the wire feeding speed is changed
Electro slag welding equipment. 12. The method of claim 11,
The reference current value is determined depending on the type of the welding wire based on the function determined in advance according to the type of the welding wire
Electro slag welding equipment.

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