Welding sliding copper contact piece and welding method

Abstract

To provide a slidable copper backing metal for welding and a welding method in which an arc does not occur even when a welding speed is increased and stable welding can be performed.SOLUTION: A slidable copper backing metal for welding 30 includes: a backing metal body part 40; and a detection terminal 18 of a molten slag bath detector 13 provided in an upper end of the backing metal body part 40 so as to be in an electrically non-contact state with the backing metal body part 40 and capable of detecting a welding voltage of the molten slag bath 7. On a surface of the backing metal body part 40 in an opening tip part side, a pocket part 45 is formed below the detection terminal 18. The pocket part 45 is concaved in an opposite side to the opening tip part 2 with respect to the surface with which a solidified slag 11 contacts, for storing molten slag of the molten slag bath 7.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a sliding copper backing for welding and a welding method.

Background Art

[0002] In the electroslag welding method, the joule heat of the molten slag existing between the wire and the base material is used as a heat source, and welding is performed while melting the base material and the wire. As a high-efficiency construction method for vertical joints, it is widely adopted for welding large structures such as shipbuilding and oil tanks.

[0003] In the electroslag welding method, it is known to use a small water-cooled sliding copper backing having a length sufficient to cover the molten slag bath. Thereby, as welding progresses, the welding torch and the carriage are raised by a rail, a chain, or the like, and the water-cooled sliding copper backing is moved along the weld line together with the torch or the carriage, enabling welding of a long weld of several tens of meters.

[0004] Also, in the electroslag welding method, although the molten slag shields the weld metal from the atmosphere, the molten slag is discharged as solidified slag from the gap between the water-cooled sliding copper backing and the weld bead as welding progresses. Therefore, during welding, flux is supplied in a timely manner to compensate for the discharged solidified slag, and the amount of the molten slag is kept substantially constant by melting it with joule heat.

[0005] Patent Document 1 describes a flux automatic addition method for non-consumable nozzle type electroslag welding, which is characterized by automatically supplying an appropriate amount of flux to the surface of the molten slag bath. In the electroslag welding with upward progression using a non-consumable nozzle, it is disclosed that the addition of flux during welding is automated to keep the depth of the molten slag bath within an appropriate range, and a stable product without welding defects such as poor penetration of the base material and slag entrapment is produced.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, since the amount of molten slag discharged per unit time is approximately proportional to the groove width and the welding speed, when the welding speed increases, the amount of flux to be supplied per unit time also increases, and the amount of molten slag in the welded part fluctuates violently. Under the condition of a constant wire feeding amount, the welding speed is inversely proportional to the groove cross-sectional area. Therefore, the smaller the groove cross-sectional area, the higher the welding speed. Due to such characteristics, in electro-slag welding, when the welding speed is increased to a certain value or more, the amount of molten slag discharged increases, and when the amount of molten slag becomes extremely small, an arc is generated, etc., and the welding tends to become unstable.

[0008] Even if the flux supply amount is automated by the flux automatic addition method as in Patent Document 1, even if the reduced amount is added, when the welding speed increases, a state where the amount of molten slag decreases occurs, and it is difficult to properly maintain the amount of molten slag, and the welding becomes unstable.

[0009] The present invention has been made in view of the above-described problems, and an object thereof is to provide a sliding copper backing for welding and a welding method capable of stably welding without generating an arc even when the welding speed is increased.

Means for Solving the Problems

[0010] The above object of the present invention is achieved by the following configuration. [1] A sliding copper backing for welding that is disposed opposite to the groove portion between a pair of base materials so as to form a molten slag bath and slides along the groove portion, a backing body portion, a detection terminal of a molten slag bath detector provided at the upper end portion of the backing body portion so as to be electrically non-contact with the backing body portion and capable of detecting the welding voltage of the molten slag bath, comprising On the surface of the tip side of the pad body portion, below the detection terminal, there is a recess on the side opposite to the tip portion from the surface where the solidified slag contacts, and a pocket portion for storing the molten slag of the molten slag bath is formed. A sliding copper pad for welding.

[0011] [2] Place the sliding copper pad for welding according to [1] toward the tip portion between a pair of base materials. While introducing flux into the tip portion, supply a welding wire from the tip of the contact chip. Move the contact chip along the tip portion and slide the sliding copper pad for welding along the tip portion to perform welding. Welding method.

Advantages of the Invention

[0012] According to the sliding copper pad for welding and the welding method of the present invention, since a pocket portion for storing the molten slag of the molten slag bath is formed in the pad body portion, even if the welding speed is increased, no arc is generated and stable welding can be performed.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a sliding copper backing for welding and a welding method using the sliding copper backing for welding according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0015] <Configuration of Welding Apparatus> First, an electro-slag welding apparatus using a sliding copper backing for welding according to an embodiment of the present invention will be described. FIG. 1 is a diagram showing a schematic configuration of an electro-slag welding apparatus according to an embodiment of the present invention. In FIG. 1, the arrow Z indicates the vertical direction along the weld line of the base material, the arrow X indicates the thickness direction of the base material, and the arrow Y indicates the direction in which a pair of base materials are arranged, that is, the direction along the surface of the base material. Therefore, the upper side means the upper side with respect to the paper surface of FIG. 1, the lower side means the lower side with respect to the paper surface of FIG. 1, the front means the left side with respect to the paper surface of FIG. 1, and the rear means the right side with respect to the paper surface of FIG. 1. Also, in FIGS. 3 to 7, assuming a state where the sliding copper backing for welding is disposed on the surface of the base material, the arrow Z indicates the longitudinal direction of the sliding copper backing for welding, the arrow X indicates the thickness direction of the sliding copper backing for welding, and the arrow Y indicates the width direction of the sliding copper backing for welding. Therefore, in the sliding copper backing for welding, the groove side is the front, and the side opposite to the groove side is the rear.

[0016] As shown in FIG. 1, the electro-slag welding apparatus 100 according to the present embodiment includes a fixed back-up member 1 and a sliding copper backing 30 for welding, a welding torch 4, a molten slag 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.

[0017] In the electro-slag welding apparatus 100, a fixed backing material 1 is disposed on the back side of the groove portion 2 of a pair of base materials 3 which are steel plates, and a sliding copper backing block 30 for welding is disposed on the front side of the groove portion 2. For the backing material 1, heat-resistant ceramics, a water-cooled copper backing block, or the like is used. Further, the sliding copper backing block 30 for welding on the front side is a copper backing block that slides in the vertical direction and is water-cooled as will be described later. However, the material of the sliding copper backing block 30 for welding may be substituted with a material other than copper.

[0018] The welding torch 4 supplies electric power to the welding wire 6 with a welding current 8 supplied from a welding power source (not shown) to weld the base material 3. Further, the welding torch 4 has a contact tip 5, and the contact tip 5 guides the welding wire 6 and supplies the welding current 8 to the welding wire 6.

[0019] The molten slag bath detector 13 detects the position of the molten slag bath 7. The flux supply device 14 inputs a flux 12 into the molten slag bath 7. Since the flux 12 melts to become molten slag, the amount of the molten slag bath 7 increases by inputting the flux 12.

[0020] The flux supply control device 15 controls the operation of the flux supply device 14 and adjusts the amount of the flux 12 input into the molten slag bath 7.

[0021] The traveling carriage 16 mounts the sliding copper backing block 30 for welding, the welding torch 4, the molten slag bath detector 13, the flux supply device 14, the flux supply control device 15, and the traveling carriage control device 17, and moves upward. That is, since the traveling carriage 16 moves integrally with the sliding copper backing block 30 for welding, the welding torch 4, the molten slag bath detector 13, the flux supply device 14, the flux supply control device 15, and the traveling carriage control device 17, their relative positional relationships do not change. When the traveling carriage 16 ascends, the contact tip 5 moves along the groove portion 2 and the sliding copper backing block 30 for welding slides along the groove portion 2, and welding is performed along the upward direction.

[0022] The traveling bogie control device 17 controls the operation of the traveling bogie 16 by increasing or decreasing the traveling speed of the traveling bogie 16.

[0023] Then, the welding wire 6 is fed from the tip of the contact tip 5 of the welding torch 4 into the groove 2 surrounded by the base material 3, the backing material 1, and the sliding copper backing 30 for welding, and is fed into the molten slag bath 7 formed in the groove 2. The welding current 8 flows from the welding wire 6 through the molten slag bath 7 to the molten metal 9. At this time, Joule heat is generated due to the welding current 8 flowing through the molten slag bath 7 and the resistance of the molten slag bath 7, and welding proceeds while melting the welding wire 6 and the base material 3.

[0024] As welding progresses, the molten metal 9 is cooled to become the weld metal 10, and a part of the molten slag bath 7 becomes a molten slag layer formed between the backing material 1 and the weld metal 10 and between the sliding copper backing 30 for welding and the weld metal 10, and this molten slag layer is cooled to become the solidified slag 11. In this way, since a part of the molten slag bath 7 becomes the solidified slag 11 covering the bead surface, it is consumed as welding progresses, and the depth Ls of the molten slag bath 7 decreases. In order to compensate for this decrease in the molten slag bath 7, it is necessary to additionally input the flux 12 that melts to become the molten slag bath 7.

[0025] The amount of the solidified slag 11 covering the bead surface varies depending on the bead width and the width of the welding groove. Also, the amount of the solidified slag 11 varies depending on the degree of adhesion and the cooling state of the backing material 1 and the sliding copper backing 30 for welding. Therefore, the amount of the solidified slag 11 is not constant, and 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 input. However, since the depth Ls of the molten slag bath 7 is unknown, if the input amount of the flux 12 is not appropriate, the depth Ls of the molten slag bath 7 will vary.

[0026] Therefore, in this embodiment, control is performed to keep the depth Ls of the molten slag bath 7 constant. Here, "constant" does not only refer to the case where the depth Ls of the molten slag bath 7 always has a single value, but also includes the case where the depth Ls of the molten slag bath 7 shows a value within a certain range considering errors. That is, the depth Ls of the molten slag bath 7 is controlled to be maintained at a predetermined depth.

[0027] And the first requirement for keeping the depth Ls of the molten slag bath 7 constant is to control the welding wire length Ld (hereinafter referred to as the dry extension Ld) from the tip of the contact chip 5 to the upper surface of the molten slag bath 7 to be a predetermined length. Also, the second requirement for keeping the depth Ls of the molten slag bath 7 constant is that the traveling carriage control device 17 controls the traveling speed of the traveling carriage 16 so that the welding current 8 has a predetermined relationship with the reference current value determined according to the wire feeding speed, that is, the reference current value and the welding current 8 are equal. At the same wire feeding speed, there is a correlation between (Ld + Ls) and the welding current 8, and by controlling the traveling speed of the traveling carriage 16 so that the reference current value and the welding current 8 are equal, (Ld + Ls) is kept constant. Note that the control of the welding wire length Ld can be achieved by detecting the molten slag bath 7 with the molten slag bath detector 13, which will be described in detail below.

[0028] <Configuration of the molten slag bath detector> Next, the configuration of the molten slag bath detector 13 will be described in detail. FIG. 2 is a diagram showing a configuration example of the molten slag bath detector 13.

[0029] As shown in FIG. 2, the molten slag bath detector 13 includes a detection terminal 18, a differential amplifier 19, a contact determination reference signal setter 20, and a comparator 21. The detection terminal 18 is made of a copper alloy, which is a conductive metal, and is provided at the upper end of the sliding copper tip 30 for welding via an insulating member 48 as will be described later. The detection terminal 18 detects a part of the welding voltage when it comes into contact with the molten slag bath 7.

[0030] Incidentally, the differential amplifier 19 of the molten slag bath detector 13 may receive the voltage at the detection terminal 18 and the voltage of the sliding copper contact 30 for welding, which is the base metal voltage. However, since the sliding copper contact 30 for welding is in contact with the molten slag bath 7 and may have a ground potential, it is preferable to ground it as shown in FIG. 2 rather than inputting the voltage of the sliding copper contact 30 for welding.

[0031] The differential amplifier 19 takes the voltage at the detection terminal 18 and the ground voltage as inputs and outputs the difference between the two voltages. The contact determination reference signal setter 20 outputs, as a reference signal, a voltage that is not misdetected by noise, for example, about half of the voltage detected when the detection terminal 18 comes into contact with the molten slag bath 7.

[0032] The comparator 21 takes the output signal of the differential amplifier 19 and the reference signal of the contact determination reference signal setter 20 as inputs, and creates a signal that determines that the detection terminal 18 and the molten slag bath 7 are in contact when the output signal of the differential amplifier 19 becomes greater than the reference signal of the contact determination reference signal setter 20. The created signal is sent to the flux supply control device 15, and the supply and stop of the flux 12 are performed from the flux supply device 14. Then, it is controlled so that the upper surface of the molten slag bath 7 is positioned at a predetermined length from the tip of the contact chip 5, and the dry extension Ld is maintained at a predetermined length. When the detection terminal 18 is not in contact with the molten slag bath 7, the welding voltage is not applied to the detection terminal 18, so the voltage of the detection terminal 18 is 0V.

[0033] Also, in the molten slag bath detector 13, if the value of the reference signal of the contact determination reference signal setter 20 is small, there is a possibility that a correct determination cannot be made due to the welding state or external noise, etc. For this reason, when oscillating the welding torch 4, in order to prevent false detection, the molten slag bath detector 13 may be provided with a low-pass filter between the differential amplifier 19 and the comparator 21.

[0034] <Sliding copper contact for welding> As described above, the sliding copper backing plate 30 for welding is disposed opposite to the groove portion 2 between the pair of base materials 3 so as to form the molten slag bath 7, and slides along the groove portion 2 as the traveling carriage 16 moves.

[0035] As shown in FIGS. 3 to 7, the sliding copper backing plate 30 for welding includes a backing plate main body portion 40 formed in a substantially rectangular plate shape, and a detection terminal 18 of the above-described molten slag bath detector 13 that can detect the welding voltage of the molten slag bath 7, which is provided in a concave groove 47 provided at the upper end portion of the backing plate main body portion 40 via an insulating member 48 so as to be electrically non-contact with the backing plate main body portion 40.

[0036] On the groove portion side 2 of the backing plate main body portion 40, a pair of contact surfaces 41 that can contact the base material 3 are formed over the entire longitudinal direction of the backing plate main body portion 40 on the surfaces on both sides in the width direction. The width of the contact surface 41 may be 7 mm or less, and preferably 5 mm or less.

[0037] Also, on the groove portion 2 side of the backing plate main body portion 40, recessed portions 43 that are slightly recessed with respect to the pair of contact surfaces 41, which are surfaces where solidified slag contacts, are formed downward on the surface at the center portion in the width direction. Further, below the detection terminal 18 and above the recessed portion 43, a pocket portion 45 that is recessed rearward from the recessed portion 43 and stores the molten slag of the molten slag bath 7 is formed.

[0038] The recessed portion 43 has a uniform cross-sectional shape in the Z direction, and is formed in a concave curved surface shape so that the bead formed in the groove portion 2 between the pair of base materials 3 and the solidified slag covering the bead surface can enter.

[0039] Also, the pocket portion 45 has a flat surface that inclines rearward as it goes upward from the upper end edge of the recessed portion 43, curves upward, and then stands up in the Z direction to the lower end surface of the concave groove 47 into which the detection terminal 18 and the insulating member 48 are fitted. The pocket portion 45 has a length in the Z direction corresponding to the depth Ls of the molten slag bath 7.

[0040] Therefore, in the present embodiment, the molten slag bath 7 is formed in a space surrounded by the surface of the groove of the pair of base materials 3, the backing material 1, and the welding sliding copper backing 30. By providing the pocket portion 45, a certain amount of molten slag in the molten slag bath 7 can be ensured. For this reason, even when the groove cross-sectional area is small and the welding speed is high, the amount of molten slag can be appropriately maintained, and welding can be stabilized without the occurrence of an arc.

[0041] Note that the pocket portion 45 may be composed of an inclined surface or a tapered inclined surface, or may be a depression, or may have an L-shape, a curved L-shape, or a spherical shape when the backing body portion 40 is viewed from the side. That is, the pocket portion 45 only needs to have a space / depression for storing the molten slag bath 7, and may only have a cylindrical hole. Also, the width of the pocket portion 45 may be substantially equal to the width of the detection terminal 18, or may be wider than the width of the detection terminal, and is determined in consideration of ease of processing and ease of detection. Specifically, in the present embodiment, the width of the pocket portion 45 is formed wider than the width of the detection terminal 18.

[0042] Also, in the present embodiment, the side surface 45a of the pocket portion 45 is a flat surface standing along the Z direction, but may be an inclined surface that widens outward in the width direction upward. Thereby, the visibility from above of the molten slag bath 7 and the like can be enhanced.

[0043] The volume of the pocket portion 45, that is, as shown in FIG. 5, the volume of the region (the shaded portion in FIG. 5) defined by the horizontal plane H1 at the lower end edge of the pocket portion 45, the horizontal plane H2 at the upper end edge, and the vertical plane V1 connecting both end edges in the width direction is preferably 2500 mm 3 or more.

[0044] The reason for setting the volume of the pocket portion 45 to 2500 mm 3 or more is that the general groove cross-sectional area to which electro-slag welding is applied is 200 - 1500 mm 2 and since the depth of the molten slag bath is 25 mm, the amount of molten slag during welding is approximately 5000 mm 3-37500 mm 3 Therefore, 2500 mm 3 is because it can compensate for approximately 50% of the amount of molten slag at the minimum groove cross-sectional area. By compensating for approximately 50% or more of the amount of molten slag at the minimum groove cross-sectional area, the molten slag bath 7 can be stably maintained, and welding can be made more stable. As a result, the welding workability is excellent, a good bead appearance can be obtained, and the occurrence of the splashing phenomenon is also minimized. For this reason, the volume of the pocket portion 45 is 2500 mm 3 or more, which is preferable.

[0045] There is no particular need to set an upper limit for the volume of the pocket portion 45, but in reality, it is preferably 12000 mm 3 or less in order to avoid an unnecessary increase in the consumption of the flux and to consider the size limitation of the copper plate.

[0046] Furthermore, a stepped surface 46 is formed between the contact surface 41 and the widthwise opening edge of the pocket portion 45. The contact surface 41 and the stepped surface 46 are provided over the surface where the solidified slag 11 contacts, that is, from the side of the recess 43 to the side of the pocket portion 45.

[0047] The stepped surface 46 makes it difficult for the viscous molten slag to enter the gap between the stepped surface 46 and the surface of the base material 3. Also, since the surface pressure is high on the contact surface 41, the slag that enters the gap between the stepped surface 46 and the surface of the base material 3 is likely to crack, and by maintaining the adhesion between the contact surface 41 and the surface of the base material 3, it is difficult to leak from the contact surface 41 side.

[0048] In the present embodiment, the stepped surface 46 has a first stepped surface 46a formed with a uniform width over the entire longitudinal direction of the patch body portion 40 adjacent to the contact surface 41, and a second stepped surface 46b formed from the widthwise opening edge of the recess 43 and the widthwise open edge of the pocket portion 45 to the first stepped surface 46a. Therefore, in the present embodiment, the stepped surface 46 is composed of two steps, the first stepped surface 46a and the second stepped surface 46b, but it may be one step or three or more steps.

[0049] Further, although the stepped surface 46 is a flat surface standing upright in the Z direction, it may be an inclined surface, a curved surface, or a concave surface. In reality, it is preferably a flat surface or a curved surface for ease of processing.

[0050] Also, the detection terminal 18 of the molten slag bath detector 13 is provided at the upper end of the pad body portion 40 and is fitted into a concave groove 47 having a U-shaped cross section that penetrates in the thickness direction via an insulating member 48.

[0051] On the side opposite to the tip portion 2 of the detection terminal 18, that is, on the rear surface of the pad body portion 40, a support plate 49 is bolt-fixed so as to close the concave groove 47, and the support plate 49 is in contact with the pad body portion 40. On the other hand, the detection terminal 18 is screwed and fixed by a screw member 60 in a form insulated from the support plate 49.

[0052] An insulating member 48 is provided over the lower surface and the side surfaces of the concave groove 47 between the detection terminal 18 and the pad body portion 40. Also, an insulating thin plate 48a of the insulating member 48 is interposed between the detection terminal 18 and the support plate 49.

[0053] Note that the insulating member 48 is preferably made of a material having thermal conductivity in order to cool the detection terminal 18. For example, ceramics are used. The insulating member 48 is preferably made of heat-resistant ceramics and may have a thickness of 0.5 to 5 mm.

[0054] The thickness of the detection terminal 18 is preferably equal to or less than the thickness of the pad body portion 40. Thereby, good maintainability can be ensured, and interference with the oscillating welding torch 4, interference with the base material 3, etc. can be suppressed.

[0055] Also, the front surface of the detection terminal 18 is preferably located at the same level as or behind the upper edge of the pocket portion 45 in the X direction. Thereby, since the pocket portion 45 is open not only on the tip portion 2 side but also upward, the detection terminal 18 can enhance the visibility from above of the molten slag bath 7 etc. in the pocket portion 45.

[0056] Note that the lower limit of the thickness of the detection terminal 18 is not particularly limited, but is preferably 4 mm or more, more preferably 5 mm or more.

[0057] Furthermore, the detection terminal 18 has an inclined surface 18a that slopes backward as it goes upward on the front surface. This also enables improving the visibility from above, such as of the molten slag bath 7.

[0058] Furthermore, as shown in FIG. 7, inside the filler metal main body portion 40, a pair of pocket holes 51 are formed in parallel to each other in the Z direction on both sides in the width direction, starting from the lower end portion. The open end of the pocket hole 51 is sealed by a stopper (not shown).

[0059] The lower parts of the respective pocket holes 51 communicate with each other through communication holes 52 extending in the width direction, and the open end of this is also sealed by a stopper (not shown). Also, at the upper parts of the respective pocket holes 51, a pair of through holes 53 communicating with the pocket holes 51 are formed from the rear surface of the filler metal main body portion 40, and a water-cooling pipe 70 (see FIG. 3) is connected to the pair of through holes 53. As a result, inside the filler metal main body portion 40, a U-shaped water-cooling path 54 is provided, with both ends positioned on the side in the width direction of the detection terminal 18.

[0060] Therefore, the detection terminal 18 is indirectly cooled by the water-cooled filler metal main body portion 40 via a heat-conductive insulating member 48, improving the heat dissipation of the detection terminal 18, preventing the temperature rise of the detection terminal 18, and suppressing the influence of the heat received from the molten slag bath 7. Also, by water-cooling the lower part of the filler metal main body portion 40 with the water-cooling path 54, slag is formed earlier, the bead shape becomes better, and the effect of preventing slag sticking can be enhanced.

[0061] On the rear surface of the filler metal main body portion 40, as shown in FIGS. 5 and 7, a mounting groove 55 for mounting a joint 80 extending from the traveling carriage 16 side is formed. As a result, the welding sliding copper filler metal 30 moves together with the traveling carriage 16 via the joint 80.

[0062] Note that the present invention is not limited to the above-described embodiments, and can be appropriately modified, improved, etc.

Example

[0063] Here, using the sliding copper backing for welding of the above-described embodiment and a copper backing without a pocket portion for the sliding copper backing for welding of this embodiment, electro-slag welding was performed on three base materials of different sizes. Table 1 shows the test conditions and the evaluation after welding.

[0064]

Table 1

[0065] Specifically, in Example 1 and Comparative Example 2, for a pair of base materials set with a plate thickness of 16 mm, a gap of 7 mm, and a groove angle of 45°, a sliding copper backing for welding without a pocket portion and a sliding copper backing for welding with a pocket volume of 1500 mm 3 were used for welding.

[0066] In Comparative Example 1 and Examples 2 to 4, for a pair of base materials set with a plate thickness of 16 mm, a gap of 6 mm, and a groove angle of 45°, a sliding copper backing for welding without a pocket portion and a sliding copper backing for welding with a pocket volume of 3000 mm 3 , 5200 mm 3 , 6300 mm 3 were used for welding.

[0067] In Example 5, for a pair of base materials set with a plate thickness of 25 mm, a gap of 6 mm, and a groove angle of 35°, a sliding copper backing for welding with a pocket volume of 3000 mm 3 was used for welding.

[0068] Also, Table 1 shows the welding speed, current, and voltage in the electro-slag welding of Examples 1 to 5 and Comparative Examples 1 to 2.

[0069] In this example, Examples 1 to 5 and Comparative Examples 1 to 2 were evaluated using three factors: weldability, bead appearance, and slag bath stability. For weldability, if the arc could not be restarted after generation and welding was impossible, it was marked as ×; if the arc was generated more than once per 600 mm of welding length and occurred frequently, it was marked as △; if no arc was generated and stable welding was performed, it was marked as 〇.

[0070] For bead appearance, if the bead was unstable and welding was impossible, it was marked as ×; if the variation in bead width was 2 mm or more at a welding length of 600 mm and the bead width was non-uniform but could withstand practical use, it was marked as 〇; if the variation in bead width was less than 2 mm at a welding length of 600 mm and the bead width was uniform, it was marked as ◎.

[0071] For slag bath stability, if the slag splashed and the slopping phenomenon continued, making welding impossible, it was marked as ×; if the slopping phenomenon occurred frequently more than 5 times at a welding length of 600 mm but welding was still possible, it was marked as 〇; if the occurrence of the slopping phenomenon was minor, less than 5 times at a welding length of 600 mm, it was marked as ◎. Note that all three evaluations were performed excluding the welding start portion.

[0072] As a result, as shown in Comparative Examples 1 and 2, when using a sliding copper backing for welding without a pocket portion, the arc generation occurred frequently in both cases, and good weldability could not be obtained. On the other hand, as shown in Examples 1 to 5, by providing a pocket portion in the sliding copper backing for welding, even when the welding speed was 50 mm / min or more, no arc was generated, and it was found that good weldability could be obtained. Also, by setting the volume of the pocket portion to 2500 mm 3 or more, it was further found that the bead width became uniform, a good bead appearance was obtained, the occurrence of the slopping phenomenon was also minor, and a stable molten slag bath was obtained.

[0073] As described above, the following matters are disclosed in this specification. (1) A sliding copper backing for welding that is disposed opposite to the groove portion between a pair of base materials so as to form a molten slag bath and slides along the groove portion, a backing body portion, At the upper end of the pad body portion, a detection terminal of a molten slag bath detector is provided so as to be electrically non-contact with the pad body portion, and the welding voltage of the molten slag bath can be detected. It is provided with On the surface of the tip side of the pad body portion, below the detection terminal, a pocket portion for storing the molten slag of the molten slag bath is formed, which is recessed on the side opposite to the tip portion from the surface where the solidified slag contacts. A sliding copper pad for welding. According to this configuration, a pocket portion for storing the molten slag of the molten slag bath is formed in the pad body portion, so that even if the welding speed is increased, no arc is generated and stable welding can be performed.

[0074] (2) The volume of the pocket portion is 2500 mm 3 or more, the sliding copper pad for welding according to (1). According to this configuration, a stable molten slag bath can be obtained, a good bead appearance can be obtained, and the occurrence of the slopping phenomenon is also minimized.

[0075] (3) On the tip side of the pad body portion, on the surfaces on both sides in the width direction, a pair of contact surfaces that can contact the base material and a step surface formed between the contact surface and the width direction opening edge of the pocket portion are formed. The contact surface and the step surface are provided from the side of the surface where the solidified slag contacts to the side of the pocket portion, the sliding copper pad for welding according to (1) or (2). According to this configuration, it is possible to make it difficult for the slag to enter the gap between the step surface and the surface of the base material, and suppress the leakage of the slag from the contact surface side.

[0076] (4) A support plate that contacts the pad body portion is attached to the side opposite to the tip portion of the detection terminal. An insulating thin plate is interposed between the detection terminal and the support plate, the sliding copper pad for welding according to any one of (1) to (3). According to this configuration, the insulation between the detection terminal and the support plate can be ensured by using an insulating thin plate.

[0077] (5) An insulating member is provided between the detection terminal and the body portion of the contact pad. The sliding copper contact pad for welding according to any one of (1) to (4). According to this configuration, the insulating property between the body portion of the contact pad and the detection terminal can be ensured by using the insulating member.

[0078] (6) The thickness of the detection terminal is equal to or less than the thickness of the body portion of the contact pad. The sliding copper contact pad for welding according to any one of (1) to (5). According to this configuration, good maintainability can be ensured, and interference with an oscillating welding torch and interference with the base material can be suppressed.

[0079] (7) The pocket portion is open on the side of the tip portion and upward. In the thickness direction of the pair of base materials, the front surface of the detection terminal is the same as the upper edge portion of the pocket portion or is located on the side opposite to the tip portion. The sliding copper contact pad for welding according to (6). According to this configuration, the visibility from above, such as a molten slag bath, can be enhanced.

[0080] (8) Inside the body portion of the contact pad, there is a U-shaped water-cooling path with both ends located on the lateral sides in the width direction of the detection terminal. The sliding copper contact pad for welding according to any one of (1) to (7). According to this configuration, the body portion of the contact pad can be cooled by the water-cooling path, the influence of heat acting on the detection terminal can be suppressed, and the formation of slag can be promoted.

[0081] (9) Place the sliding copper contact pad for welding according to any one of (1) to (8) toward the tip portion between the pair of base materials. While injecting flux into the tip portion, supply a welding wire from the tip of the contact chip. Move the contact chip along the tip portion and slide the sliding copper contact pad for welding along the tip portion for welding. Welding method. According to this configuration, by using a copper welding pad in which a pocket part for storing the molten slag of the molten slag bath is formed in the pad main body part, even if the welding speed is increased, no arc is generated and stable welding can be performed.

Explanation of Signs

[0082] 2 Groove part 3 Base material 4 Welding torch 5 Contact tip 6 Welding wire 7 Molten slag bath 9 Molten metal 12 Flux 13 Molten slag bath detector 14 Flux supply device 16 Traveling carriage 18 Detection terminal 30 Sliding copper pad for welding 40 Pad main body part 41 Contact surface 43 Recess 45 Pocket part 47 Concave groove 48 Insulating member 100 Electro-slag welding device

Claims

1. A sliding copper pad for welding, which is disposed opposite to the groove portion between a pair of base materials so as to form a molten slag bath and slides along the groove portion, comprising a pad main body, a detection terminal of a molten slag bath detector provided at the upper end portion of the pad main body so as to be electrically non-contact with the pad main body and capable of detecting the welding voltage of the molten slag bath, and on the surface of the pad main body on the groove portion side, below the detection terminal, a pocket portion is formed which is recessed on the side opposite to the groove portion from the surface where the solidified slag contacts and stores the molten slag of the molten slag bath. The sliding copper pad for welding.

2. The volume of the pocket portion is 2500 mm ３ or more. The sliding copper pad for welding according to claim 1.

3. On the groove portion side of the pad main body, on the surfaces on both sides in the width direction, a pair of contact surfaces capable of contacting the base material and a step surface formed between the contact surface and the width direction opening edge of the pocket portion are formed, The contact surface and the step surface are provided from the side of the surface where the solidified slag contacts to the side of the pocket portion. The sliding copper pad for welding according to claim 1.

4. A support plate that contacts the pad main body is attached to the side of the detection terminal opposite to the groove portion, An insulating thin plate is interposed between the detection terminal and the support plate. The sliding copper pad for welding according to claim 1.

5. An insulating member is provided between the detection terminal and the pad main body. The sliding copper pad for welding according to claim 1.

6. The thickness of the detection terminal is equal to or less than the thickness of the pad main body. The sliding copper pad for welding according to claim 1.

7. The pocket portion opens to the groove portion side and upward, In the thickness direction of the pair of base materials, the front surface of the detection terminal is the same as the upper edge of the pocket portion or is located on the side opposite to the root face portion, the sliding copper backing for welding according to claim 6.

8. Inside the backing body portion, there is a U-shaped water cooling path with both ends located on the side in the width direction of the detection terminal, the sliding copper backing for welding according to claim 1.

9. Place the sliding copper backing for welding according to any one of claims 1 to 8 toward the root face portion between the pair of base materials, While injecting flux into the root face portion, supply a welding wire from the tip of the contact chip, Move the contact chip along the root face portion and slide the sliding copper backing for welding along the root face portion for welding. Welding method.

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