JP7235635B2 - Sliding copper pad for welding and welding method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a sliding copper pad for welding and a welding method.

An electroslag welding method and an electrogas welding method are known as an example of a welding method for vertical welding of base materials arranged opposite to each other. In the electroslag welding method, the base metal and the wire are melted to form a weld metal using electric resistance heating of molten slag existing between the wire and the base material as a heat source. A general electroslag welding method is called a consumable nozzle type or a non-consumable nozzle type. In the consumable nozzle type, the consumable nozzle is fixed in the groove, and the electrode wire is continuously supplied into the nozzle. . Since the consumable nozzle is melted and consumed as welding progresses, a mechanism for lifting the nozzle is not necessary, but the welding length is limited to the length of the consumable nozzle.

On the other hand, in the non-consumable nozzle type, the nozzle is controlled to rise as welding progresses, and the welding length is limited by the lifting mechanism and nozzle length. Since it is difficult to weld a long length of several tens of meters, a fixed water-cooled copper patch is used for a short portion of several meters, or four sides are surrounded by steel plates and the interior is vertically welded. It will be In addition, when long welding is performed by the above electroslag welding method, difficulties arise in fixing and restraining the water-cooled copper pad, arrangement of the consumable nozzle in the groove, lifting mechanism of the non-consumable nozzle, etc., and welding work is also impossible. become stable.

On the other hand, in the electrogas welding method, the welding torch and truck are raised using rails and chains as the welding progresses. It enables long welding of several tens of meters. In this case, the length of the copper pad is sufficient as long as it is long enough to cover the molten metal and slag, and it is not necessary to cover the entire weld line, so it has the advantage of being compact and lightweight. There is also Therefore, even in the electroslag welding method, long welding is possible by using a small water-cooled sliding copper plate while raising the welding torch and cart using a rail or chain. is not covered over the entire weld line, a new problem arises in that molten slag or molten metal flows between the water-cooled sliding copper plate and the weld bead and is consumed.

In order to solve this problem, Patent Document 1 discloses that the depth of the slag bath is detected during welding, and when the depth of the slag bath becomes shallower as the slag is consumed, flux is automatically supplied from above to compensate for this. An electroslag welding method is disclosed. In addition, in Patent Document 2, a copper block pressed by a spring is disclosed in order to be able to move vertically in order to solve the problem of slag leakage caused by the gap between the base material and the contact metal due to misalignment of the base material. are applied as parts on both sides to ensure surface contact on both sides of the base material and the weld bead to prevent slag leakage.

JP 2016-215214 A Japanese Utility Model Laid-Open No. 60-171694

However, in Patent Document 1, as the water-cooled sliding copper pad, which is almost the same as that used in the electrogas welding method is used, even if the base metal is misaligned or the base metal mounting surface is angled. In this case, the water-cooled sliding copper pad strikes the base metal obliquely, and the contact with both sides of the base metal and weld bead becomes line contact or point contact, so molten slag or molten metal easily leaks out. There was a problem of hoarding. Further, in Patent Document 2, even if the simple misalignment in which the base material mounting surfaces are parallel surfaces having a step can be dealt with, if an angle occurs between the base material mounting surfaces, the sliding copper pad of the prior art cannot be used. Similarly, line contact or point contact is formed, and molten slag or molten metal easily leaks out.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems described above, and an object of the present invention is to provide a welding slide capable of preventing molten slag or molten metal from leaking out from between a base material and a sliding copper pad. An object of the present invention is to provide a dynamic copper pad and a welding method.

Therefore, the above object of the present invention is achieved by the following configuration (1) relating to a sliding copper pad for welding.
(1) A sliding copper pad for welding that is disposed facing a groove between a pair of base metals so as to form a molten slag bath or a molten metal bath and slides along the groove,
a base body;
at least one rotating member rotatable with respect to the metal body,
The rotating member has a contact surface capable of contacting the surface of the base material,
A sliding copper pad for welding, wherein the contact surface is rotatable with respect to the pad body so as to be in surface contact with the surface of the base material.
According to this configuration, the contact metal main body portion and at least one rotating member rotatable with respect to the contact metal main body portion are provided, and the rotating member has a contact surface capable of contacting the surface of the base material. Since the contact surface is rotatable with respect to the base metal body so as to be in surface contact with the surface of the base material, slag leakage or molten metal leakage due to misalignment or angle difference of the base material can be prevented. can be prevented.

Further, preferred embodiments of the present invention relating to a sliding copper pad for welding relate to the following (2) to (6).
(2) comprising a pair of rotating members;
The pair of rotating members has a pair of contact surfaces rotatable with respect to the contact metal main body,
The sliding copper for welding according to (1), wherein the rotating member has a columnar shape with a substantially D-shaped cross section in which the longitudinal direction extends along the groove portion and a part of the outer peripheral surface forms a flat portion. the prize money.
According to this configuration, the pair of rotating members has a columnar shape with a substantially D-shaped cross section in which the longitudinal direction extends along the groove portion and a portion of the outer peripheral surface forms a flat portion, so that the flat portion is wide. The area is in surface contact with the side surface of the base material, and it is possible to prevent slag leakage or molten metal leakage due to misalignment or angle difference of the base material.

(3) The sliding copper contact for welding according to (1) or (2), wherein the contact metal main body and the rotating member each have a water cooling path.
According to this configuration, the contact metal main body and the rotating member can be effectively cooled by the cooling water supplied to the water cooling path.

(4) The rotating member is rotatably supported with respect to the contact metal main body through slide bearings that support supporting shafts provided at both ends in the longitudinal direction of the rotating member, (1) to (3). The sliding copper pad for welding according to any one of.
According to this configuration, since both ends of the rotating member are rotatably supported by the contact metal main body via the sliding bearings, the rotating member can smoothly rotate corresponding to the side surface of the base material.

(5) The welding according to any one of (1) to (4), wherein the facing surfaces of the contact metal main body that face the pair of base materials are chamfered on both edges in the width direction. Sliding copper pad for use.
According to this configuration, since both edges in the width direction of the base metal main body are chamfered, the base metal main body does not interfere with the base material even if there is a difference in angle. Surface contact with the flat portion of the rotary member is ensured.

(6) A rod-shaped tungsten electrode that can be inserted into the molten slag bath is arranged on the upper part of the base metal body,
Any one of (1) to (5), wherein the slag bath height can be detected by measuring the potential difference between the welding sliding copper pad and the tungsten electrode in the molten slag bath. The sliding copper pad for welding described in .
According to this configuration, the slag bath height can be accurately detected.

Further, the above object of the present invention is achieved by the following configuration (7) relating to the welding method.
(7) A sliding copper pad for welding according to any one of (1) to (6) is placed toward the groove between a pair of base metals, and a flux is added into the groove. is filled, a welding wire is supplied from the tip of the contact tip, the contact tip is moved along the groove, and the sliding copper pad for welding is slid along the groove to weld Welding method.
According to this configuration, a long welded portion can be welded with a small and lightweight sliding copper pad for welding.

According to the sliding copper contact for welding of the present invention, it comprises a contact metal main body and at least one rotating member rotatable with respect to the contact metal main body, the rotating member being the surface of the base material. and the contact surface is rotatable with respect to the main body of the base material so as to be in surface contact with the surface of the base material. slag leakage or molten metal leakage can be prevented.

Further, according to the welding method of the present invention, a sliding copper pad for welding is arranged toward the groove between a pair of base metals, and flux is filled in the groove, and from the tip of the contact tip Welding wire is supplied, the contact tip is moved along the groove, and the sliding copper pad for welding is slid along the groove for welding, so it is small and lightweight. Long welds can be welded with gold.

FIG. 1 is a diagram showing an example of a schematic configuration of an electroslag welding apparatus according to one embodiment of the present invention. FIG. 2 is a diagram showing a configuration example of a molten slag bath detector. FIG. 3 is a top view of the sliding copper pad for welding according to this embodiment. 4 is a cross-sectional view taken along line IV-IV of FIG. 3. FIG. FIG. 5 is a cross-sectional view showing a state in which a copper pad and a sliding copper pad for welding are arranged in the groove of the butt joint. FIG. 6 is a cross-sectional view showing a state in which a sliding copper pad for welding is arranged on the mounting surface of the base material having an angle. FIG. 7 is a diagram showing a state in which a bevel portion of a base material having a misalignment of 6 mm is welded by the sliding copper pad for welding according to the present embodiment.

An embodiment of a sliding copper pad for welding according to the present invention will now be described in detail with reference to the drawings. Although the sliding copper pad for welding according to the present invention can be applied to both electroslag welding and electrogas welding, electroslag welding will be described as an example in the following description.

<Configuration of welding equipment>
First, an electroslag welding apparatus using a sliding copper pad for welding according to an embodiment of the present invention will be described. FIG. 1 is a diagram showing an example of a schematic configuration of an electroslag welding apparatus according to one embodiment of the present invention.

As shown in FIG. 1, the direction indicated by arrow Z is the vertical direction (vertical direction), and the direction indicated by arrow X is the right direction in the plate thickness direction (lateral direction). The direction from the back surface to the front surface is defined as the front direction of the horizontal lateral direction Y.

As shown in FIG. 1, an electroslag welding apparatus 100 according to the present embodiment includes a fixed copper pad 1 and a sliding copper pad for welding 30, a welding torch 4, a molten slag bath detector 13, a flux It comprises a 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 pad 1 is arranged on the back side of the groove, and a sliding copper pad 30 for welding is arranged on the front side of the groove. Here, instead of the copper backing metal 1 on the back side, a backing material made of heat-resistant ceramics may be used. Also, the sliding copper pad for welding 30 on the front side is a copper pad that slides in the vertical direction and is water-cooled. However, as the sliding copper pad for welding 30, a substitute for copper may be used.

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

A molten slag bath detector 13 detects the position of the molten slag bath 7 . A flux feeder 14 feeds the flux 12 into the molten slag bath 7 . Since the flux 12 melts and becomes molten slag, the amount of the molten slag bath 7 is increased by adding the flux 12 .

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

The traveling carriage 16 is equipped with a sliding copper pad for welding 30, a welding torch 4, a molten slag bath detector 13, a flux supply device 14, a flux supply control device 15, and a traveling carriage control device 17. arrow Z direction). That is, the traveling carriage 16 moves integrally with the welding sliding copper pad 30, 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. Therefore, their relative positional relationship does not change. Welding is performed along the upward direction by raising the traveling carriage 16 .

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

Then, the welding wire 6 is fed from the contact tip 5 of the welding torch 4 into the groove surrounded by the base material 3, the copper pad 1 and the sliding copper pad for welding 30, and the welding wire 6 is fed into the groove. into a molten slag bath 7 formed therein. A 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 by the welding current 8 flowing through the molten slag bath 7 and the resistance of the molten slag bath 7, and the welding progresses while the welding wire 6 and the base material 3 are melted.

As the welding progresses, the molten metal 9 cools to become the weld metal 10, and a portion of the molten slag bath 7 is welded between the copper pad 1 and the weld metal 10 and the welding sliding copper pad 30. A molten slag layer is formed between the metal 10 and the molten slag layer is cooled to become a solidified slag 11 . In this manner, a part of the molten slag bath 7 becomes solidified slag 11 covering the bead surface, so 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 add flux 12 that melts to form the molten slag bath 7. FIG.

The amount of solidified slag 11 covering the bead surface varies depending on the bead width and the width of the weld groove. The amount of solidified slag 11 also varies depending on the degree of adhesion between the copper pad 1 and the sliding copper pad for welding 30 and the cooling state. 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 to be introduced. However, since the depth Ls of the molten slag bath 7 is unknown, the depth Ls of the molten slag bath 7 will fluctuate if the amount of the flux 12 input is not appropriate.

Therefore, in the present embodiment, control is performed to keep the depth Ls of the molten slag bath 7 constant. Here, constant is not limited to the case where the depth Ls of the molten slag bath 7 always has one value, but the case where the depth Ls of the molten slag bath 7 shows a value within a certain range in consideration of errors. is also included. That is, the depth Ls of the molten slag bath 7 is controlled so as to be kept at a predetermined depth.

The first requirement for making the depth Ls of the molten slag bath 7 constant is that the welding wire length Ld (hereinafter referred to as dry extension Ld) from the tip of the contact tip 5 to the upper surface of the molten slag bath 7 is , is controlled to have a predetermined length. A second requirement for making the depth Ls of the molten slag bath 7 constant is a predetermined relationship between the welding current 8 and a reference current value determined according to the wire feed speed. The traveling speed of the traveling vehicle 16 is controlled by the traveling vehicle control device 17 so that the current value and the welding current 8 become equal.

<Configuration of Molten Slag Bath Detector>
Next, the configuration of the molten slag bath detector will be described in detail. FIG. 2 is a diagram showing a configuration example of the molten slag bath detector 13. As shown in FIG.

As shown in FIG. 2 , the molten slag bath detector 13 according to this embodiment has 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 tungsten, which is a conductive metal and a refractory metal, and is generally water-cooled. Also, when the detection terminal 18 comes into contact with the molten slag bath 7, it detects a part of the welding voltage.

A differential amplifier 19 receives the voltage of the detection terminal 18 and the voltage of the sliding copper pad for welding 30 as inputs and outputs the difference between the two voltages. Since the sliding copper pad for welding 30 is in contact with the base material 3, the voltage of the sliding copper pad for welding 30 is the base metal voltage.

The contact determination reference signal setter 20 outputs a voltage approximately half the voltage detected when the detection terminal 18 contacts the molten slag bath 7 as a reference signal. For example, since the detection terminal 18 normally detects a welding voltage of 6 V or more, the reference signal is set to a voltage of about 3 V, which is half of that. When the detection terminal 18 is not in contact with the molten slag bath 7, no welding voltage is applied to the detection terminal 18, so the voltage of the detection terminal 18 is 0V.

The output signal of the differential amplifier 19 and the reference signal of the contact determination reference signal setter 20 are input to the comparator 21, and the output signal of the differential amplifier 19 becomes larger than the reference signal of the contact determination reference signal setter 20. When the detection terminal 18 and the molten slag bath 7 come into contact with each other, a signal is generated. The generated signal is sent to the flux supply control device 15, and the flux 12 is supplied and stopped by the flux supply device 14. FIG. Then, the upper surface of the molten slag bath 7 is controlled to be positioned at a predetermined length from the tip of the contact tip 5, and the dry extension Ld is maintained at the predetermined length.

<Sliding Copper Plate for Welding>
Next, the configuration of the sliding copper pad for welding will be described in detail. As shown in FIGS. 3 to 5, the sliding copper pad for welding 30 includes a pair of rotating members 31, 31 and a pad body 41 that holds the rotating member 31 rotatably.

The rotating member 31 is a substantially columnar member having a substantially D-shaped cross section, and has a flat portion (contact surface) 32 extending in the longitudinal direction by partially cutting out the outer peripheral surface thereof. The plane portion 32 is formed parallel to the axis CL of the rotating member 31 . The width of the flat portion 32 is, for example, 5 to 15 mm. Small-diameter support shaft portions 33 are formed at both ends of the rotating member 31 in the axial direction, and are rotatably fitted to sliding bearings 39 fixed to the contact metal body portion 41 . As shown in FIG. 4, the slide bearing 39 has an outer shape with a substantially D-shaped cross section, and a flat portion 39a is provided on a part of the outer diameter surface.

In addition, a blind hole 34 is formed in the axial direction inside the rotating member 31 from one end side (lower end in FIG. 4). A stop plug 36 is fixed to a female screw 35 formed at the open end of the blind hole 34 to seal the blind hole 34 . Further, the blind hole 34 is provided with a pair of upper and lower through-holes 37 extending from the opposite side of the flat portion 32 to the blind hole 34 and communicating with each other in the radial direction. The blind hole 34 and the pair of through holes 37 form part of a water cooling path 38 through which cooling water for cooling the rotating member 31 flows.

The contact metal main body 41 is a substantially rectangular plate-shaped member, and a pair of substantially D-shaped cross-sectional holes 42 having openings 42a on one side surface 41a of the contact metal main body 41 are formed at both edges in the width direction. It is formed in the longitudinal direction (vertical direction in FIG. 3). One side surface 41a is a surface facing the base material 3 when the sliding copper pad for welding 30 is placed on the base material 3, as shown in FIG.

A side surface 41 a between the pair of substantially D-shaped cross-sectional holes 42 in the contact metal main body 41 forms a slightly recessed recess 43 . Further, as shown in FIG. 2, the detection terminal 18 of the molten slag bath detector 13 is arranged opposite to the concave portion 43 . A pair of blind holes 44 from the lower end portion of the contact metal main body 41 are arranged substantially parallel to the substantially D-shaped cross-sectional holes 42 at portions near the center of each of the substantially D-shaped cross-sectional holes 42 , similar to the blind holes 34 of the rotating member 31 . formed. As with the blind hole 34, the open end of the blind hole 44 is sealed with a stop plug (not shown).

Each blind hole 44 is formed with a pair of through holes 45 that communicate with the blind holes 44 on the opposite side of the concave portion 43 and are spaced apart in the vertical direction. The blind hole 44 and the pair of through holes 45 form part of a water cooling path 38 for flowing cooling water, which will be described later. In addition, chamfers 46 are applied to both widthwise edge portions of the side surfaces 41 a of the contact metal main body portion 41 . The blind hole 34 and the pair of through-holes 37 of the rotating member 31 and the blind hole 44 and the pair of through-holes 45 of the cover body 41 are connected to one by a connecting pipe (not shown). forming

Here, as shown in FIG. 3, the length _L1 of the perpendicular line from the center O of the rotating member 31 to the plane portion 32 is equal to the center O of the substantially D-shaped hole 42 in the contact metal main body portion 41 (that is, the rotating member 31 ) is longer than the length L ₂ of the perpendicular to the opening 42a (that is, L ₁ >L ₂ ).

Therefore, the pair of rotating members 31, which are rotatably fitted in the substantially D-shaped cross-sectional holes 42 in the cover main body 41, are fitted with the slide bearings 39 at the support shafts 33 at both ends in the axial direction. The flat portion 32 is assembled so as to protrude from the opening 42a of the contact metal body portion 41 by L ₁ -L ₂ . In other words, the pair of rotating members 31 are supported by the contact metal main body 41 so that the plane portions 32 of the contact metal main body 41 protrude from the side surfaces 41a of the contact metal main body 41 toward the base material 3 by L ₁ -L ₂ .

Further, as shown in FIG. 4, the slide bearing 39 having a substantially D-shaped cross section has a perpendicular length L 3 from the center O of the rotating member 31 (which is the same as the center of the support hole of the slide bearing 39) to the plane portion _39a . is the same as the length _L2 of the perpendicular line from the center O of the substantially D-shaped hole 42 of the cover body 41 to the opening 42a. Therefore, the flat portion 39 a of the slide bearing 39 does not protrude from the side surface 41 a of the contact metal body portion 41 .

As shown in FIGS. 5 and 6, such a sliding copper pad for welding 30 is provided with a pair of rotating members 31 on the side surface (front side) 3a of the base material 3 having the copper pad 1 disposed on the back surface. It is arranged with the flat portion 32 in contact therewith. Since the pair of rotating members 31 are rotatable with respect to the contact metal main body 41, each plane portion 32 of the pair of rotating members 31 rotates following the side surface 3a of the base material 3, and as shown in FIG. Even if there is an angular difference between the side surfaces 3a of the two base materials 3, or if there is a misalignment between the side surfaces 3a of the two base materials 3, the side surfaces 3a of the base materials 3 and the plane portions 32 of the pair of rotating members 31 ensure surface contact. Furthermore, since chamfers 46 are applied to both edges in the width direction of the side surfaces 41a of the contact metal main body 41, even if there is an angle difference between the side surfaces 3a of the two base materials 3, the width of the contact metal main body 41 is Both directional edges and the side surface 3a of the base material 3 do not interfere with each other.

From the above, the copper pad 1, the groove portion 2 of the base material 3, part of the side surface 3a of the base material 3, part of the cylindrical surface of the rotating member 31, and the concave portion 43 (side surface 41a) of the pad main body 41 to form a reservoir for molten slag.

In this manner, the pair of rotating members 31 are arranged with their flat portions 32 in surface contact with the side surface 3a of the base material 3, and the cooling water is passed through the water cooling path 38 to cool the rotating members 31 and the contact metal body portion 41. is cooled from the inside, the groove portion 2 is filled with the flux 12. - 特許庁Then, the welding wire 6 is supplied from the tip of the contact tip 5, the contact tip 5 is moved along the groove portion 2, and the sliding copper pad for welding 30 is slid along the groove portion 2 for welding. do.

Since the plane portions 32 of the pair of rotating members 31 are in surface contact with the side surface 3a of the base material 3, even if there is misalignment or angle difference between the two base materials 3, the molten slag or molten metal will not displace the base material. 3 and the pair of rotating members 31 can be prevented from leaking out from between the plane portions 32 of the rotating members 31 . In addition, a long welded portion can be welded with the small and lightweight sliding copper pad for welding 30 .

FIG. 7 shows an example of butt-welding a base material 3 with a misalignment of 6.0 mm using the sliding copper pad for welding 30 of the present embodiment. As shown in FIG. 7, by using the sliding copper pad for welding 30 of the present embodiment, even the base material 3 with a large misalignment can be welded satisfactorily.

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate. For example, although welding of butt joints has been described in the above embodiment, the present invention is not limited to this, and can be similarly applied to T-shaped joints, V-shaped joints, etc., with similar effects. Further, in the above embodiment, the case of performing vertical welding by an electroslag welding device has been described, but it is also applicable to an electrogas welding device, and in that case, both vertical welding and horizontal welding are possible. becomes.

Further, in the above embodiment, the case where the sliding copper pad for welding 30 includes a pair of rotating members 31, 31 and the pad body 41 that rotatably holds the rotating member 31 has been described. Even if the sliding copper pad for welding 30 has only one rotating member 31 rotatable with respect to the pad main body 41, the side surface 3a of the base material 3 and the flat portion 32 of the rotating member 31, In addition, since the side surface 3a of the base material 3 and the contact metal main body 41 are in surface contact, the same effect as described above can be obtained. However, it is more preferable for the sliding copper pad for welding 30 to include a pair of rotating members 31, 31 because it can cope with a large angular difference and misalignment that may occur on the side surfaces 3a of both base materials 3.

1 copper pad 2 groove portion 3 base material 3a side surface 5 contact tip 6 welding wire 7 molten slag bath (molten slag)
12 flux 18 detection terminal (tungsten electrode)
30 Sliding copper pad for welding 31 Rotating member 32 Flat portion (contact surface)
33 support shaft portion 38 water cooling path 39 sliding bearing 41 contact metal main body portion 41a side surface (facing surface of contact metal main body portion)
46 Chamfer 100 Electroslag welding device Ls Depth of molten slag bath (slag bath height)

Claims (6)

A sliding copper pad for welding that is arranged opposite to a groove between a pair of base metals so as to form a molten slag bath or a molten metal bath and slides along the groove,
a base body;
a pair of rotating members rotatable with respect to the corresponding metal body,
The rotating member has a contact surface capable of contacting the surface of the base material,
The contact surface is rotatable with respect to the base metal body so as to be in surface contact with the surface of the base material,
The pair of rotating members has the contact surface rotatable with respect to the contact metal main body,
The rotating member has a columnar shape with a substantially D-shaped cross section in which the longitudinal direction extends along the groove portion and a part of the outer peripheral surface forms the contact surface,
At both edges in the width direction of the cover main body, substantially D-shaped holes in cross section are formed in which the pair of rotating members are rotatably fitted,
A sliding copper contact for welding, wherein the pair of rotating members are supported by the contact metal main body so that the contact surfaces protrude toward the base material. 2. The sliding copper contact metal for welding according to claim 1 , wherein said contact metal body and said rotating member each have a water cooling path. The welding member according to claim 1 or 2 , wherein the rotating member is rotatably supported with respect to the contact metal main body via slide bearings that support supporting shafts provided at both ends in the longitudinal direction of the rotating member. Sliding copper pad. The sliding copper contact for welding according to any one of claims 1 to 3 , wherein the facing surface of the contact metal main body facing the pair of base materials is chamfered on both widthwise edges. Money. A rod-shaped tungsten electrode that can be inserted into the molten slag bath is arranged on the upper part of the base metal body,
The slag bath height can be detected by measuring a potential difference between the sliding copper pad for welding and the tungsten electrode in the molten slag bath, according to any one of claims 1 to 4 . Sliding copper pad for welding. The sliding copper pad for welding according to any one of claims 1 to 5 is arranged toward the groove between a pair of base metals, and the groove is filled with flux, A welding method comprising supplying a welding wire from the tip of a contact tip, moving the contact tip along the groove, and sliding the sliding copper pad for welding along the groove for welding.

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