JP5033704B2 - Jig unit and circumferential welding apparatus using the same - Google Patents

Description

  The present invention mainly has a large-diameter opening formed in a sealed drum can or tank top plate suitable for storing and transporting various liquids and various powders such as petroleum products, chemicals, pharmaceuticals, foods, and paints. And a jig unit used in a circumferential welding apparatus in which a cylindrical large-diameter base forming an injection port and a cylindrical small-diameter base forming a ventilation port are joined to the small-diameter opening by circumferential welding, respectively. In particular, when an arc is welded circumferentially between a large and small opening peripheral part of a top plate and a large and small base in an atmosphere of a shielding gas such as argon gas, the intensity of the arc is increased. Protects the eyes and skin of the operator by shielding the light, and the shielding gas released from the welding torch can be used to enhance the shielding effect of the welded portion and prevent the welded portion from being oxidized. Capable of stable energy density A jig unit that absorbs excess heat from the weld and suppresses thermal distortion due to welding, and prevents bead burn-off and perforation, and circumferential welding using the jig unit. It relates to the device.

In general, sealed drums and tanks made of stainless steel plates are used to store and transport various liquids and powders such as petroleum products, chemicals, and pharmaceuticals.
Such stainless steel sealed drum cans and tanks are more expensive than iron drum cans and tanks. It is common.

Conventionally, a stainless steel sealed drum can has a lower end portion of a cylindrical body and a plate-like ground plate joined together by winding, welding, or the like, and a top plate having an upper end portion of the body and an inlet and a ventilation port, Are produced by bonding them by winding or the like.
The top plate of the drum can is provided with a cylindrical large-diameter base that forms an inlet and a cylindrical small-diameter base that forms a ventilation port. Filling, draining the contents of the drum, cleaning the drum, etc.

  The large-diameter base that forms the inlet and the small-diameter base that forms the ventilation port are generally manufactured separately from the top plate, and the top 100a is formed in the opening 100a formed in the top plate 100 as shown in FIG. The end portion of the base 101 is inserted from the front surface side of the plate 100, and the opening 100a of the top plate 100 is circumferentially welded from the back surface side of the top plate 100 to the periphery of the opening 100a of the top plate 100 and the end portion of the base 101. It is joined to the peripheral edge (see, for example, Patent Document 1).

  By the way, when joining the periphery of the opening 100a of the top plate 100 and the end of the base 101 by welding, the top plate 100 and the base 101 are temporarily fixed by an appropriate jig (not shown), and TIG welding is performed in this state. The TIG welding torch is moved along the opening 100a of the top plate 100 and the end of the base 101 while a shielding gas such as argon gas flows from the torch toward the peripheral edge of the opening 100a of the top plate 100 and the end of the base 101. The peripheral edge of the opening 100a of the top plate 100 and the end of the base 101 are circumferentially welded by an arc in an atmosphere of shielding gas while being swung.

  However, in TIG welding using a TIG welding torch, an arc is generated between the tungsten electrode rod inserted into the TIG welding torch and the welding member (top plate 100 and base 101). There is a problem that the worker may face the intense light directly and cause an obstacle to the eyes of the worker. In particular, arc light is even more problematic because it contains ultraviolet and infrared rays that are harmful to the eyes and skin in addition to intense visible light.

Further, in TIG welding using a TIG welding torch, a shielding gas is flowed from the shield nozzle provided at the tip of the TIG welding torch toward the peripheral edge of the opening 100a of the top plate 100 and the end of the base 101. Although the periphery of the opening 100a of the top plate 100 and the end of the base 101 are welded by an arc in a gas atmosphere, the shield gas is simply diffused and released from the shield nozzle. Since the periphery of the location is in an open state, it is difficult to completely block the intrusion of air into the molten pool by the shielding gas, and the shielding effect by the shielding gas is reduced.
As a result, the welded part is oxidized, and the work to remove the oxidized part is required, which increases the number of work processes and easily causes welding defects such as pinholes and blowholes. was there.

  Furthermore, in TIG welding using a TIG welding torch, only the shield gas is diffused and released from the shield nozzle, so the concentration of the shield gas around the arc generated during welding decreases, and an arc with a high energy density is generated. There was a problem that an unstable arc could not be obtained. In this case, when the peripheral portion of the opening 100a of the top plate 100 and the end portion of the base 101 are joined by welding, the members are not sufficiently melted and the surface side of the peripheral portion of the opening 100a of the top plate 100 and the base 101 are joined. There is a problem that a gap is formed between the two and a gap corrosion occurs.

In addition, the top plate 100 of the drum can must be fixed by welding a large-diameter base 101 that forms the inlet and a small-diameter base 101 that forms the ventilation port, respectively. In this case, since the large-diameter base 101 that forms the injection port and the small-diameter base 101 that forms the ventilation port are separately attached to the top plate 100 by circumferential welding using a TIG welding apparatus or the like. There is a problem that it takes time and labor to attach 101, and the workability is inferior.
JP 2002-53132 A

  The present invention has been made in view of such problems, and its purpose is to perform circumferential welding of an opening peripheral portion of a top plate such as a drum can and a base by an arc in an atmosphere of a shielding gas. , Shields the eyes and skin of the operator by shielding the intense light of the arc, and also uses the shielding gas released from the welding torch to enhance the shielding effect of the welded part and oxidize the welded part. A stable arc with a high energy density can be obtained, and the excess heat of the weld can be absorbed to suppress thermal distortion caused by welding and prevent bead burnout and perforation. It is another object of the present invention to provide a jig unit excellent in workability and a circumferential welding apparatus using the same.

  In order to achieve the above-mentioned object, the invention according to claim 1 of the present invention provides an end of an annular base that forms an inlet or a vent from the surface side of the top plate in an opening formed in the top plate of a drum can or a container. Insert the welding torch along the opening of the top plate and the end of the base while flowing the shielding gas from the welding torch from the back side of the top plate toward the opening peripheral edge of the top plate and the end of the base. A jig unit used in a circumferential welding apparatus in which the end of the base is circumferentially welded by an arc in an atmosphere of a shielding gas to the peripheral edge of the opening of the top plate while being pivoted, the jig unit comprising: A top jig facing the back and a lower jig that supports the base inserted into the opening of the top board from the lower surface side, and an opening periphery of the top board between the lower jig and the lower jig An upper jig for holding and fixing the vicinity of the part, the upper jig An annular upper clamp that comes into contact with the top surface of the top plate facing the back in a surface contact state from the upper surface side, and is disposed in the upper clamp so as to be horizontally rotatable, and the tip of the welding torch is disposed on the outer peripheral edge. It has a torch insertion hole to be inserted or a torch insertion notch, and shield gas released from the welding torch between the opening peripheral edge of the top plate and the base, and shields the periphery of the welding area between the top plate and the base It consists of a disc-shaped lid that forms a shield gas space for shielding with gas, and the lid clamps the upper clamp together with the welding torch as the welding torch rotates while shielding the arc light. It is characterized in that it is configured to rotate inside.

  According to a second aspect of the present invention, a step portion on which the outer peripheral edge portion of the lid body is supported and mounted so as to be slidably rotatable is formed on the inner circumferential surface of the upper clamp, and the torch insertion hole or torch of the lid body When the welding torch inserted in the insertion notch is turned, the lid is configured to rotate together with the welding torch in a state where the outer peripheral edge thereof is in surface contact with the stepped portion of the upper clamp. .

  The invention of claim 3 of the present invention is characterized in that a cooling water passage through which cooling water flows is formed in the upper clamp of the upper jig.

  According to a fourth aspect of the present invention, there is provided an annular lower clamp for supporting the top plate by contacting the lower jig in the surface contact state from the lower surface side in the vicinity of the opening peripheral portion of the top plate facing back, and the lower clamp. A base support for supporting the base inserted into the opening of the top plate, and a positioning collar formed on the outer peripheral surface of the end of the base by biasing the base support upward. It consists of an elastic body that presses against the opening peripheral edge of the top plate. The opening peripheral edge of the top plate is clamped and fixed by the lower clamp and the upper clamp of the upper jig, and the positioning collar of the base is fixed to the base support and elastic. It is characterized in that the body is configured to be pressed against the opening peripheral edge of the top plate.

  The invention of claim 5 of the present invention is characterized in that a cooling water passage through which cooling water flows is formed in the lower clamp of the lower jig.

  According to the sixth aspect of the present invention, the end of the large-diameter base and the ventilation port that form the inlet from the surface side of the top plate in the large-diameter opening and the small-diameter opening formed in the top plate of the drum can or the container. The end of the small-diameter base that forms the base plate is inserted, the end of the large-diameter base from the back side of the top plate to the peripheral edge of the large-diameter opening of the top plate, and the top plate from the back side of the top plate A circumferential welding apparatus in which an end of a small-diameter base is circumferentially welded by an arc in an atmosphere of shielding gas to a peripheral edge of a small-diameter opening, the circumferential welding apparatus having a work surface having a work surface And supporting the large-diameter base inserted in the large-diameter opening of the top plate while holding and fixing the vicinity of the large-diameter opening peripheral portion of the top plate placed on the work surface of the cabinet body. The jig unit according to any one of claims 1 to 5 and the work surface of the cabinet body. The jig according to any one of claims 1 to 5, wherein the vicinity of the periphery of the small-diameter opening of the top plate facing the back is clamped and supported, and the small-diameter base inserted into the small-diameter opening of the top plate is supported. A fixture unit, a jig support mechanism provided on the work surface of the cabinet body and supporting the two jig units, and a large diameter of the top plate by releasing a shield gas from the tip portion of the cabinet body. A welding device equipped with a swivelable welding torch for circumferentially welding the end of a large-diameter base by arc in a shield gas atmosphere to the peripheral edge of the opening, and is disposed in the cabinet body and shields from the tip It is composed of a welding apparatus equipped with a swivelable welding torch that discharges gas and circumferentially welds the end of the small-diameter base to the peripheral edge of the small-diameter opening of the top plate by an arc in an atmosphere of shielding gas. The feature is That.

The jig unit of the present invention can provide the following excellent effects.
(1) That is, the jig unit of the present invention has an opening of the top plate between the lower jig and the lower jig that supports the base plate inserted into the back and the opening of the top plate from the lower surface side. It is composed of an upper jig that holds the vicinity of the peripheral edge, and the upper jig can be horizontally rotated within the upper clamp, an annular upper clamp that contacts the upper peripheral edge of the top plate in a surface contact state from the upper surface side. The torch insertion hole or the torch insertion notch is inserted into the outer peripheral edge portion of the welding torch, and is released from the welding torch between the opening peripheral edge portion of the top plate and the base. And a disc-shaped lid that forms a shield gas space for shielding the periphery of the welded portion of the top plate and the base with the shield gas, and the lid is rotated with the swiveling movement of the welding torch. Upper clamp with welding torch Therefore, when the end of the base is circumferentially welded to the opening edge of the top plate, the arc light is shielded by the lid of the upper jig. It is possible to perform welding work safely without directly looking at the intense light of the eyes or being exposed to ultraviolet rays or infrared rays harmful to eyes and skin.
(2) Since the jig unit of the present invention forms a shield gas space in which the shield gas released from the welding torch is accumulated in the upper jig and the periphery of the welded portion of the top plate and the base is shielded by the shield gas. Intrusion of air into the weld pool and the weld bead portion immediately after welding can be reliably and well blocked.
As a result, if the jig unit of the present invention is used, the shielding effect of the welded part by the shielding gas will be greatly enhanced, and oxidation of the welded part can be reliably and satisfactorily prevented, and pinholes and the like can be prevented. Welding without welding defects can be performed, and the product quality can be greatly improved.
(3) In the jig knit according to the present invention, since the concentration of the shielding gas around the arc is increased by the shielding gas space formed in the upper jig, the generated arc is restricted by the thermal pinch effect by the shielding gas, and the energy density is reduced. It becomes a high and stable arc, and the penetration of the welded member becomes large and the back wave is easily generated.
As a result, when the jig knit of the present invention is used, when the opening peripheral edge of the top plate and the end of the base are circumferentially welded, the member is sufficiently melted, and the top peripheral edge surface side of the top plate A gap is not formed between the base and the base, so that the problem of gap corrosion can be solved, and the strength of the joint between the top plate and the base is greatly increased.
(4) The jig unit of the present invention has a torch insertion hole or a torch insertion notch into which the tip of the welding torch is inserted into the lid, and the tip of the welding torch inserted into the torch insertion hole Since the part faces the shield gas space, the concentration of the shield gas around the tungsten electrode rod inserted in the welding torch becomes high and the tungsten electrode rod becomes difficult to wear, extending the life of the tungsten electrode rod. I can plan.
(5) The jig unit of the present invention forms a step portion on the inner peripheral surface of the upper clamp, on which the outer peripheral edge portion of the lid body is supported and mounted so as to be slidably rotatable. When turning the welding torch inserted in the hole or notch insertion notch, the lid rotates together with the welding torch in a state where its outer peripheral edge is in surface contact with the stepped portion of the upper clamp. It becomes difficult for the shielding gas in the shielding gas space to escape to the outside, the shielding effect by the shielding gas can be further enhanced, and the structure becomes very simple.
(6) Since the jig unit of the present invention forms a cooling water passage through which cooling water flows in the upper clamp of the upper jig and the lower clamp of the lower jig, the opening peripheral edge of the top plate and the end of the base Are welded reliably and satisfactorily by the upper clamp and lower clamp, the thermal distortion of the weld is greatly suppressed, and beats are prevented from being burned out and perforated. Will be.
(7) The jig unit of the present invention includes an annular lower clamp that supports the top plate by contacting the lower jig in the surface contact state from the lower surface side in the vicinity of the opening peripheral edge of the top plate facing back, A base support that is disposed in the clamp so as to be movable up and down and supports the base inserted into the opening of the top plate, and a positioning collar formed on the outer peripheral surface of the end of the base by biasing the base support upward And an elastic body that press-contacts the opening peripheral edge of the top plate with the lower clamp and the upper clamp of the upper jig to clamp and fix the opening positioning peripheral portion of the base Since the elastic body is pressed against the opening edge of the top plate, when the circumferential edge of the opening edge of the top plate and the end of the base is circumferentially welded, the opening peripheral edge of the top plate and the base are securely connected without gaps. In addition, it is possible to perform circumferential welding without welding defects. .

The circumferential welding device of the present invention includes a cabinet main body, a large-diameter base that is disposed in the cabinet main body, clamps and fixes the vicinity of the large-diameter opening periphery of the top plate, and is inserted into the large-diameter opening of the top plate. A jig unit that supports the small-diameter base that is inserted in the small-diameter opening of the top plate, and is disposed in the cabinet main body, holds and fixes the vicinity of the small-diameter opening peripheral portion of the top plate, and A jig support mechanism that is provided in the cabinet body and supports both the jig units, and is disposed in the cabinet body. The shield gas is discharged from the front end portion and a large diameter opening peripheral portion of the top plate has a large diameter. A welding device equipped with a swivelable welding torch for circumferential welding by arc in the atmosphere of shielding gas at the end of the base, and a cabinet body, which discharges shielding gas from the tip to release the top plate Small diameter perimeter It is composed of a welding device equipped with a swivelable welding torch that welds the end of a small-diameter base to the circumference by means of an arc in an atmosphere of shielding gas. A large-diameter base that forms a hole and a small-diameter base that forms a ventilation opening in the small-diameter opening of the top plate can be fixed simultaneously by circumferential welding, which makes it easy to attach multiple bases to the top plate. It can be done in time and has excellent workability.
Furthermore, since the circumferential welding apparatus of the present invention includes a jig unit that shields arc light and enhances the shielding gas effect by the shielding gas, circumferential welding is performed on the peripheral edge of the opening of the top plate and the base. In this case, the operator's eyes and skin can be protected from intense arc light, oxidation of the weld can be prevented, and a stable arc with high energy density can be obtained. Excess heat can be absorbed to suppress thermal distortion caused by welding and to prevent the beads from being burned out or perforated.

  1 and 2 show a jig unit according to an embodiment of the present invention and a circumferential welding apparatus using the jig unit. The circumferential welding apparatus is a top plate of a stainless steel sealed drum can (or tank). The large-diameter base 51 that forms the injection port and the small-diameter base 51 that forms the ventilation port can be simultaneously fixed to the 50 large-diameter opening 50a and the small-diameter opening 50a by circumferential welding. Yes.

  That is, as shown in FIGS. 1 and 2, the circumferential welding apparatus is provided on a cabinet main body 1 having a horizontal work surface 1a on the front side, and a work surface 1a of the cabinet main body 1, and is placed on the back. The periphery of the large-diameter opening 50a of the plate 50 is clamped and fixed in the vertical direction, and the jig unit 2 for supporting the large-diameter base 51 inserted into the large-diameter opening 50a of the top plate 50, and the cabinet body 1 The periphery of the small-diameter opening 50a of the top plate 50 disposed on the work surface 1a is sandwiched and fixed from above and below, and the small-diameter base 51 inserted into the small-diameter opening 50a of the top plate 50 is supported. The jig unit 2 is provided on the work surface 1a of the cabinet main body 1 and is provided in the cabinet main body 1 for supporting the two jig units 2 and the shield gas G from the tip. Release A welding apparatus 4 having a swivelable welding torch 28 for circumferentially welding the end of a large-diameter base 51 by an arc in an atmosphere of a shielding gas G at the periphery of a large-diameter opening 50a of the top plate 50; Disposed in the main body 1, the shield gas G is discharged from the tip, and the end of the small-diameter base 51 is circumferentially welded with an arc in the atmosphere of the shield gas G to the peripheral edge of the small-diameter opening 50 a of the top plate 50. The welding apparatus 4 includes a welding torch 28 that can turn freely.

Incidentally, as shown in FIG. 7, an annular large-diameter base 51 that forms an injection port attached to the top plate 50 of the drum can and an annular small-diameter base 51 that forms a ventilation opening are both formed on the outer peripheral surface of one end. An annular positioning collar 51a that contacts the peripheral edge of the opening 50a of the plate 50 is provided, and a flange 51b that faces the top plate 50 is provided on the outer peripheral surface of the other end to form an annular positioning collar 51a. The end portions thus inserted are respectively inserted into the large-diameter opening 50a and the small-diameter opening 50a formed in the top plate 50 from the surface side of the top plate 50, and are fixed to the periphery of the opening 50a of the top plate 50 by circumferential welding.
Each of the large-diameter base 51 and the small-diameter base 51 is formed in an internal screw type base 51 in which a female screw is formed on the inner peripheral surface.

As shown in FIGS. 1 and 2, the cabinet body 1 has a plurality of casters 5 and support legs 6 on the bottom surface side, and is configured such that a substantially upper half on the front side is opened forward. A horizontal work surface 1a on which two jig units 2 and a jig support mechanism 3 for supporting them are installed is formed at the front side intermediate position in 1 and the front side in the cabinet body 1 is also formed. At the upper position, a touch panel type operation panel 7 for setting welding conditions, electrode positions and the like of the two welding apparatuses 4 is provided.
Inside the cabinet body 1, a welding power supply device 8 and its control device (not shown), a welding gas cylinder (not shown) and its accessories (not shown), and cooling water supplied to the jig unit 2 are provided. A chiller unit 9 and a fluorescent lamp 10 are stored.

  The two jig units 2 sandwich and fix the vicinity of the periphery of the large-diameter opening 50a of the top plate 50 and the vicinity of the periphery of the small-diameter opening 50a of the top plate 50 from the top and bottom, respectively. The large-diameter base 51 inserted into the large-diameter opening 50a and the small-diameter base 51 inserted into the small-diameter opening 50a of the top plate 50 are supported, respectively, on the periphery of the large-diameter opening 50a of the top plate 50. When the end of the large-diameter base 51 and the end of the small-diameter base 51 are circumferentially welded to the peripheral edge of the small-diameter opening 50a of the top plate 50 by an arc in an atmosphere of a shielding gas G such as argon gas. In addition to shielding the intense light of the arc, the shielding gas G emitted from the welding torch 28 is used to enhance the shielding effect of the welded part and absorb the excess heat of the welded part. is there.

  Note that the two jig units 2 are configured in the same structure by the same members and the same parts, and differ only in size. Therefore, here, one jig unit 2 (the small diameter of the top plate 50) is used. Only the jig unit 2 supporting the small-diameter base 51 by sandwiching and fixing the vicinity of the peripheral part of the opening 50a from above and below is described, and the other jig unit 2 (the vicinity of the peripheral part of the large-diameter opening 50a of the top plate 50) is described. As for the jig unit 2) that supports and supports the large-diameter base 51 from above and below in the vertical direction, the same reference numerals are assigned to the same members / parts, and detailed description thereof is omitted.

  As shown in FIGS. 3, 6 and 7, the jig unit 2 includes a small-diameter base 51 inserted into the peripheral portion of the small-diameter opening 50 a of the top plate 50 and the small-diameter opening 50 a of the top plate 50. The lower jig 2 'supported from the lower surface side is disposed opposite to the upper position of the lower jig 2' so that the vicinity of the peripheral edge of the opening 50a of the top plate 50 between the lower jig 2 'from the vertical direction. It is composed of an upper jig 2 ″ for holding and fixing.

  That is, as shown in FIG. 7, the lower jig 2 ′ is an annular lower clamp 11 that supports the top plate 50 by abutting in the surface contact state from the lower surface side near the periphery of the opening 50 a of the top plate 50 facing back. And a base support 12 that is disposed in the lower clamp 11 so as to be movable up and down and supports the base 51 inserted into the opening 50 a of the top plate 50, and the end of the base 51 by urging the base support 12 upward. It comprises an elastic body 13 that presses the positioning flange 51a formed on the outer peripheral surface of the top plate 50 against the peripheral edge of the opening 50a of the top plate 50. While being clamped and fixed by the clamp, the positioning collar 51a of the base 51 is pressed against the peripheral edge of the opening 50a of the top plate 50 by the base support 12 and the elastic body 13.

  Specifically, the lower clamp 11 is fixed to the upper surface of a lower plate 24 of the jig support mechanism 3 described later by a bolt 15 and is a lower base 11a with a bottomed cylindrical flange formed of a metal material such as an aluminum alloy. And an annular lower clamp member 11b formed of a copper material having excellent thermal conductivity, which is fixed to the upper surface of the lower base 11a with bolts 15 and is brought into contact with the peripheral portion of the opening 50a of the top plate 50 in a surface contact state from the lower surface side. A substantially annular cooling water passage 11c through which cooling water flows is formed on the lower surface of the lower clamp member 11b, and a cooling water inlet 11d communicating with the cooling water passage 11c and a cooling water are formed in the lower base 11a. Water outlets (not shown) are respectively formed.

The base support 12 is formed in a substantially convex shape by a metal material such as an aluminum alloy, and is inserted into the lower clamp 11 so as to be slidable in the vertical direction, and a cylindrical portion 12a for supporting the base 51, and the cylindrical portion 12a. And a shaft portion 11b inserted into the base 51.
The base support 12 is inserted into the lower clamp 11 so as to be movable up and down, and is moved upward by an elastic body 13 comprising a compression coil spring interposed between the shaft portion 11b and the bottom wall portion of the lower base 11a. While being urged, it is prevented from coming off by a retaining bolt 14 that is inserted into the bottom wall portion of the lower base 11a so as to be movable up and down and screwed to the shaft portion.
The urging force (elastic force) of the elastic body 13 is lowered when the base support 12 is resisted by the elastic force of the elastic body 13 when a load of the top plate 50 is applied to the base support 12 via the base 51. It is set to be.

  On the other hand, as shown in FIG. 7, the upper jig 2 ″ has an annular upper clamp 16 that abuts in the surface contact state from the upper surface side in the vicinity of the periphery of the opening 50 a of the top plate 50 facing back, and in the upper clamp 16. The torch insertion hole 17a is disposed so as to be horizontally rotatable and the distal end portion of the welding torch 28 is inserted in the outer peripheral edge portion, and the welding torch is provided between the peripheral edge portion of the opening 50a of the top plate 50 and the base 51. And a disc-shaped lid 17 that forms a shield gas space S for accumulating the shield gas G released from 28 and shielding the periphery of the welded portion of the top plate 50 and the base 51 with the shield gas G. 17 is configured to rotate in the upper clamp 16 together with the welding torch 28 as the welding torch 28 rotates while shielding the arc light.

Specifically, the upper clamp 16 is fixed to the lower surface of the upper plate 25 of the jig support mechanism 3 to be described later with a bolt 15 and is formed of an annular upper base 16a formed of a metal material such as an aluminum alloy, and an upper base 16a. An upper clamp member 16b formed of a copper material having excellent thermal conductivity, which is fixed to the lower surface by a bolt 15 and abuts in the surface contact state from the upper surface side in the vicinity of the periphery of the opening 50a of the top plate 50. A substantially annular cooling water passage 16c through which cooling water flows is formed on the upper surface of the clamp member 16b, and a cooling water inlet 16d and a cooling water outlet (not shown) communicating with the cooling water passage 16c are formed on the upper base 16a. ) Are formed.
Further, the inner diameter of the upper clamp member 16b is smaller than the inner diameter of the upper base 16a. Therefore, a stepped portion 16e is formed on the inner peripheral surface of the upper clamp 16.

The lid body 17 is formed in a disk shape from a metal material such as a ceramic material or an aluminum alloy material, and an outer peripheral edge portion thereof is supported and mounted on the step portion 16e of the upper clamp 16 so as to be slidably rotatable.
A torch insertion hole 17 a into which the tip of the welding torch 28 is inserted is formed on the outer peripheral edge of the lid body 7, and a step portion of the upper clamp 16 is formed on the outer peripheral surface of the lid body 7. An annular flange 17b is formed on 16e so as to be slidably rotatable in a surface contact state.
The lid 17 is disposed in the upper clamp 16 so as to be horizontally rotatable in a state in which the flange portion 17b is supported by the step portion 16e of the upper clamp 16 so as to be slidable and rotatable. A shield gas space S is formed between the peripheral edge portion and the base 51 so as to accumulate the shield gas G released from the welding torch 28 and shield the periphery of the welding portion of the top plate 50 and the base 51 with the shield gas G. It has become.
Further, the lid body 17 shields the light of the arc when the welding torch 28 inserted in the torch insertion hole 17a is turned, and moves together with the welding torch 28 along with the turning movement of the welding torch 28. It rotates within the clamp 16.

  The jig support mechanism 3 supports the upper jig 2 ″ of the two jig units 2 at the same height position from the work surface 1a of the cabinet body 1 as shown in FIGS. The lower jig 2 'of the fixture unit 2 is supported so as to be movable up and down while facing the two upper jigs 2 ". The two lower jigs 2' are respectively supported from the two upper jigs 2". A set position (position shown in FIGS. 1, 2, 3, and 4) where the top plate 50 and the large and small cap 51 can be set on the two lower jigs 2 ′ separated from each other, and two upper jigs The top plate 50 supported by two lower jigs 2 ′ in the vicinity of 2 ″ is provided near the periphery of the large diameter opening 50 a and the periphery of the small diameter opening 50 a by the upper jig 2 ″ and the lower jig 2 ′. Welding work positions that can be held and fixed from above and below (positions shown in FIGS. 6 and 7) And it is capable to move up and down over and.

  That is, as shown in FIGS. 3 to 6, the jig support mechanism 3 includes a rectangular base 18 fixed to the work surface 1 a of the cabinet body 1 by bolts 15, pillars 19 erected at the four corners of the base 18, and A rectangular support plate that is fixed to the upper end of each support column 19 in a state of facing the base 18 and has two elongated holes 20a through which the welding torches 28 of the two welding apparatuses 4 are inserted so as to be pivotable. 20, a lifting plate 21 disposed on the upper surface of the base 18, a fluid pressure cylinder 22 attached to the lower surface side of the base 18 and moving the lifting plate 21 up and down, and a positioning key 23 on the upper surface of the lifting plate 21. The lower plate 24 positioned and the lower surface side of the support plate 20 are fixed with bolts, and match the two long holes 20a of the support plate 20, so that the two welding devices 4 An upper plate 25 having two circular holes 25a through which welding torches 28 are inserted so as to be pivotable, guide posts 26 erected on both ends of the lower plate 24, and lower surfaces of both ends of the support plate 20 are provided. A guide holder 27 is fixed and a guide post 26 is slidably fitted. An upper jig 2 ″ is provided on the lower surface side of the upper plate 25 and on the peripheral edge of the two circular holes 25a. The lower jig 2 ′ is fixed to the upper surface of the lower plate 24 by the bolt 15 in a state of facing the upper jig 2 ″ of the upper plate 25.

  Thus, according to the jig support mechanism 3, when the fluid pressure cylinder 22 is extended, the elevating plate 21 and the lower plate 24 are raised while being guided by the guide post 26 and the guide holder 27 to be moved to the lower plate 24. When the two fixed lower jigs 2 'are raised to the welding operation position (position shown in FIG. 6) and the fluid pressure cylinder 22 is shortened, the elevating plate 21 and the lower plate 24 are moved to the guide post 26 and the guide holder. The two lower jigs 2 ′ that are lowered while being guided by 27 and fixed to the lower plate 24 are lowered to the set position (position shown in FIG. 3).

  The lower plate 24 to which the two lower jigs 2 ′ and the two guide posts 26 are fixed and the upper plate 25 to which the two upper jigs 2 ″ and the two guide holders 27 are fixed include a top plate 50 of the drum can. The lower plate 24 has three sets of lower plates 24 with different intervals between the two lower jigs 2 ', and the upper plate 25 has two upper portions. Three sets of upper plates 25 having different intervals between the jigs 2 ″ are prepared.

  As shown in FIGS. 1 and 2, the two welding devices 4 are disposed in the cabinet body 1 so as to face each other at a predetermined interval, and on the periphery of the large-diameter opening 50 a of the top plate 50. The end of the large-diameter base 51 and the end of the small-diameter base 51 are circumferentially welded with an arc in the atmosphere of the shielding gas G to the peripheral edge of the small-diameter opening 50a of the top plate 50, respectively. Each of these welding apparatuses 4 uses a TIG welding apparatus.

  Since the two welding apparatuses 4 have the same configuration and the same structure, only one welding apparatus 4 will be described here, and the other welding apparatus 4 has the same members / parts. The same reference numerals are assigned and detailed descriptions thereof are omitted.

  As shown in FIGS. 8 to 12, the welding apparatus 4 allows a shielding gas G such as argon gas to flow from the tip, and a welding torch 28 into which a tungsten electrode rod 28b is inserted, and a welding torch 28 to freely turn. And a torch swivel unit 29 that is supported so as to be movable and adjustable in the horizontal direction and height, a welding power supply device 8, a gas cylinder for welding (not shown), and the like. When welding 51, the welding torch 28 is lowered to the position of the top plate 50 and the base 51 at the welding position (position shown in FIGS. 6 and 7), and the welding torch 28 shields from the tip at this position. While the gas G is flowing, the shield 50 moves between the peripheral edge of the opening 50a of the top plate 50 and the end of the base 51 while turning around the opening 50a of the top plate 50 and the end of the base 51 at a predetermined speed. It is adapted to circumference welded by arc in an atmosphere of G.

  As shown in FIGS. 8 and 9, the welding torch 28 is inserted with a copper collet (not shown) for holding and fixing the tungsten electrode rod 28 b in an insulating torch body 28 a so as to be movable up and down. A cylindrical shield nozzle 28c that discharges a shielding gas G such as argon gas is attached to the tip of the torch body 28a, and the tungsten electrode rod 28b projects the tip of the shield nozzle 28c by several mm. It is held and fixed to the collet in the state. A conventionally known TIG welding torch is used for the welding torch 28.

  The torch turning unit 29 has an opening 50a in the top plate 50 held and fixed at a welding position (position shown in FIGS. 6 and 7) by an upper jig 2 ″ and a lower jig 2 ′ provided in the jig support mechanism 3. When the end of the base 51 is welded to the peripheral edge, the welding torch 28 is lowered to the vicinity of the welding position, and the welding torch 28 is opened at the position at a predetermined speed at the opening 50a of the top 50 and the end of the base 51. The welding torch 28 can be supported so as to be turnable, adjustable in the horizontal direction, and adjustable in height.

  That is, as shown in FIGS. 8 to 11, the torch turning unit 29 includes a support frame 30 disposed in the cabinet body 1 and two support shafts 31 on the support frame 30 via the front and rear guide shafts 31. A frame 32 supported in a horizontally movable manner in the front-rear direction (left-right direction in FIG. 2 and the up-down direction in FIG. 11), and a horizontal guide shaft 32 a of the frame body 32 in the left-right direction (left-right direction in FIG. 1). 11 and the left / right direction of FIG. 11), and a turntable 33 that is supported in a vertical posture on the support frame 30 and has an output shaft 34a facing upward, and an output of the turn drive motor 34. A turning guide body 35 attached to the shaft 34a in a horizontal posture and turning around the output shaft 34a of the turning drive motor 34. The turning guide body 35 has an ant-shaped guide rail. 5a is supported so as to be reciprocally movable along the longitudinal direction of the turning guide body 35, can be locked to the turning guide body 35 side at a predetermined position, and a shaft 36 and a bearing 37 are provided on the lower surface side of the turning table 33. Via a swivel slider 38 that is rotatably coupled to each other, a horizontal guide body 39 that is fixed on the top surface of the swivel base 33 in the front-rear direction of the cabinet body 1, and a guide rail (shown in the figure). The slider body 40 is supported so as to be reciprocally movable along the longitudinal direction of the guide body 39 via the omission), and can be locked to the guide body 39 side at a predetermined position. The horizontal support arm 41 is fixed in a posture along the front-rear direction, and the front end of the support arm 41 is fixed in a posture along the left-right direction of the cabinet body 1. A horizontal guide body 42 in a horizontal posture, and a horizontal movement slider 43 supported on a front surface of the horizontal guide body 42 so as to be reciprocally movable along a longitudinal direction of the horizontal guide body 42 via a guide rail 42a and stopped at a predetermined position. And a horizontal screw shaft 44 that is screwed into the horizontal movement slider 43 and rotatably supported by the horizontal guide body 42 in a posture along the guide rail 42a. A laterally moving motor 45 for reverse rotation, a longitudinal guide body 46 fixed to the front surface of the laterally moving slide 43 in a vertical orientation, and supported by the longitudinal guide body 46 through a guide rail 46a so as to be movable up and down. A torch support member 47 that supports the welding torch 28 in a vertical posture, and a vertical screw that is screwed into the torch support member 47 and is rotatably supported by the vertical guide body 46 in a posture along the guide rail 46a. The shaft 48 and the vertical guide body 46 are provided with a vertical movement motor 49 that rotates the vertical screw shaft 48 forward and backward.

Thus, according to the torch turning unit 29, when the turning guide body 35 is turned by the turning drive motor 34, the turning slider 38 locked at a predetermined position of the turning guide body 35 is moved to the vertical axis 36. In addition, the swivel base 33 is coupled to the swivel base 33 via a bearing 37, and the swivel base 33 is supported by a lateral guide shaft 32a of the frame body 32 so as to be movable in the left-right direction of the cabinet body 1, and the frame body 32 is The turntable 33 turns around the output shaft 34 a of the turning drive motor 34 in combination with the direction guide shaft 31 being supported so as to be movable in the front-rear direction of the cabinet body 1.
As a result, the support arm 41 attached to the upper surface of the swivel base 33 via the guide body 39 and the slider 40 for front and rear movement also swivels together with the swivel base 33 and the lateral guide body 42 provided at the tip of the support arm 41. The horizontal movement slider 43, the vertical guide body 46, the torch support member 47, and the like also turn together with the turntable 33, and the welding torch 28 attached to the torch support member 47 in a vertical posture includes the opening 50 a and the base of the top plate 50. It will turn along the end of 51.

The torch turning unit 29 moves the turning slider 38 along the turning guide body 35 and changes the distance L between the axis of the turning drive motor 34 and the shaft 36 fixed to the upper surface of the turning slider 38. Thus, the turning radius of the welding torch 28 can be adjusted.
In this embodiment, the torch turning unit 29 of one of the welding apparatuses 4 (the right side welding apparatus 4 in FIG. 1) is arranged so that the welding torch 28 forms a path of a perfect circle having a diameter of 73 mm, and the other welding apparatus. The torch turning unit 29 of the device 4 (the welding device 4 on the left side in FIG. 1) is set so that the welding torch 28 draws a true circular locus having a diameter of 37 mm.

Further, the torch turning unit 29 is attached to the lateral movement slider 43 via the torch support member 47 and the like by adjusting the lateral movement slide 43 in the horizontal direction by the lateral screw shaft 44 and the lateral movement motor 45. The welding torch 28 can be moved and adjusted in the left-right direction.
As a result, the torch turning unit 29 adjusts the position of the welding torch 28 of the two welding devices 4 according to the diameter of the top plate 50 of the drum can by welding and adjusting the welding torch 28 in the horizontal direction. It can be changed to the optimum position.
In this embodiment, the torch turning unit 29 of one welding device 4 (the right welding device 4 in FIG. 1) has a distance of 110 mm between the turning center of the welding torch 28 and the center of the top plate 50, The torch turning unit 29 of the other welding device 4 (the welding device 4 on the left side in FIG. 1) has a distance between the turning center of the welding torch 28 and the center of the top plate 50 of 125 mm, 160 mm, or 140 mm or 190 mm. Each is set to be 210 mm.

Further, the torch turning unit 29 can adjust the height of the welding torch 28 by adjusting the torch support member 47 in the vertical direction by means of the vertical screw shaft 48 and the vertical movement motor 49. .
In this embodiment, each of the torch turning units 29 of the two welding apparatuses 4 has the respective welding torches 28 automatically height when welding the peripheral portion of the opening 50 a of the top plate 50 and the base 51. It is adjusted so that the welding position can be taken.

Next, using the jig unit 2 and the circumferential welding device 4 described above, a large-diameter base 51 for forming an inlet in the large-diameter opening 50a and a small-diameter opening 50a of the drum can and a small-diameter base for forming a ventilation opening. The case where 51 is each fixed by circumferential welding is demonstrated.
The top plate 50 is made of a stainless steel top plate 50 having a thickness of 1.5 mm, and the large-diameter base 51 and the small-diameter base 51 are each made of a stainless steel base 51. Furthermore, the welding conditions such as the welding current, arc length, turning speed of the left and right welding torches 28, the supply amount of the shielding gas G, the tip shape of the tungsten electrode rod 28b, the material and thickness of the top plate 50, the base 51 Needless to say, the optimum conditions are set according to the material and the like.

  First, the large-diameter base 51 and the small-diameter base 51 are respectively inserted into the lower clamps 11 of the two lower jigs 2 ′ in the set position with the flange portions 51 b facing downward. The small-diameter base 51 is supported by the base support 12 in the lower clamp 11.

  Next, with the top plate 50 of the drum can turned to the back, a large-diameter base 51 is formed in the large-diameter opening 50a formed in the top plate 50, and a small-diameter base 51 is formed in the small-diameter opening 50a formed in the top plate 50. The top plate 50 is placed on the lower clamps 11 of the two lower jigs 2 'at the set position so as to fit each other. Then, the base support 12 in each lower clamp 11 descends against the elastic force of the elastic body 13 due to the load of the top plate 50, and the periphery of the large-diameter opening 50 a and the small-diameter opening 50 a periphery of the top plate 50. The lower clamp 11 abuts in the surface contact state in the vicinity of the respective parts. As a result, the top plate 50 and the large and small cap 51 are supported by the two lower jigs 2 '(see FIG. 3). At this time, the large and small base 51 is urged upward by the elastic body 13 and the base support 12, and the flange portion 17 b is in pressure contact with the peripheral edge of the opening 50 a of the top plate 50.

  When the top plate 50 and the large and small caps 51 are set on the two lower jigs 2 ', the jig support mechanism 3 is operated to raise the two lower jigs 2' from the set position to the welding work position. Then, the periphery of the large-diameter opening 50a and the periphery of the small-diameter opening 50a are clamped and fixed by the two upper clamps 16 and the lower clamp 11 from the vertical direction (see FIG. 6). Also at this time, the large and small base 51 is urged upward by the elastic body 13 and the base support 12, and the flange portion 17 b is in pressure contact with the peripheral portion of the opening 50 a of the top plate 50.

When the top plate 50 and the large and small caps 51 are held and fixed by the two jig units 2, the two welding devices 4 are operated so that the large and small caps 51 are circumferentially arranged at the peripheral portions of the large and small openings 50a. It is fixed by welding.
That is, the welding torches 28 of the two welding apparatuses 4 are lowered to the welding position by the torch turning unit 29, and the tip of the welding torch 28 is inserted into the torch insertion hole 17a of the lid 17 of the upper jig 2 ″. (See FIGS. 6 and 7) In this state, cooling is performed in the cooling water passages 16c and 11c of the upper clamp 16 of the upper jig 2 ″ and the lower clamp 11 of the lower jig 2 ′. Welding of tungsten electrode rod 28b, top plate 50 and base 51 of welding torch 28 in the atmosphere of shielding gas G while flowing water and flowing shielding gas G such as argon gas from shielding nozzle 28c of welding torch 28 An arc is generated between the parts.

  When the arc is generated, the welding torch 28 is swung along the opening 50a of the top plate 50 and the end of the base 51 by the torch swivel unit 29 while flowing the shield gas G from the shield nozzle 28c, and in the upper clamp 16. The periphery of the opening 50a of the top plate 50 and the end of the base 51 are circumferentially welded by an arc in the atmosphere of the shielding gas G while rotating the lid 17 of the top plate 50.

At this time, since the distal end portion of the welding torch 28 is inserted into the torch insertion hole 17a of the lid 17 of the upper jig 2 ″ and desired in the shield gas space S, the intense light of the generated arc is the upper portion. It will be shielded by the lid 17 of the jig 2 ″, and it will be safe to say that the operator will not directly look at the intense light from the arc or will be exposed to ultraviolet rays or infrared rays harmful to eyes and skin. Welding work can be performed.
Further, since the shielding gas G released from the welding torch 28 is accumulated in the shielding gas space S of the upper jig 2 ″, the periphery of the welding portion of the top plate 50 and the base 51 is shielded by the shielding gas G. It is possible to reliably and satisfactorily block the intrusion of air into the weld pool and the weld bead portion immediately after welding, reliably and satisfactorily prevent the weld from being oxidized, and without welding defects such as pinholes. Can greatly improve the quality of the product.
Furthermore, since the concentration of the shielding gas G around the arc is increased by the shielding gas space S of the upper jig 2 ″, the generated arc is narrowed down by the thermal pinch effect by the shielding gas G and becomes a stable arc with high energy density. As the welding member melts and the back wave is easily generated, the members (the peripheral edge of the opening 50a of the top plate 50 and the end of the base 51) are sufficiently melted as shown in FIG. No gap is formed between the peripheral surface of the opening 50a of the opening 50 and the base 51, the problem of gap corrosion can be solved, and the strength of the joint between the top plate 50 and the base 51 can be solved. Will be greatly improved.
In addition, since the lid body 17 rotates together with the welding torch 28 in a state where the flange portion 17b is in surface contact with the step portion 16e of the upper clamp 16, the shield gas G in the shield gas space S is difficult to escape to the outside. Thus, the shielding effect by the shielding gas G can be further enhanced, and the structure is extremely simple.
In addition, since the cooling water flows through the cooling water passages 16c and 11c of the upper clamp 16 of the upper jig 2 ″ and the lower clamp 11 of the lower jig 2 ′, the welded portion is surely secured by the upper clamp 16 and the lower clamp 11. And it cools well, while suppressing the thermal distortion of a welding part, a bead melt-off and a perforation are prevented reliably.

  When the circumferential welding between the top plate 50 and the large and small cap 51 is completed, the welding torch 28 of the two welding apparatuses 4 is returned to the original position by the torch turning unit 29 and the jig support mechanism 3 As a result, the lower jig 2 'holding and fixing the top plate 50 at the welding position is lowered from the welding work position to the set position. Thereby, the top plate 50 to which the large and small caps 51 are fixed can be taken out from the lower jig 2 '.

  In the above-described embodiment, the lower clamp 11 of the lower jig 2 ′ is constituted by the lower base 11a and the lower clamp material 11b, and the upper clamp 16 of the upper jig 2 ″ is replaced by the upper base 16a and the upper base 16a. Although the upper clamp member 16b is used, in other embodiments, the lower base 11a and the lower clamp member 11b are integrally formed to form the lower clamp 11, and the upper base 16a and the upper clamp member 16b are formed. The upper clamp 16 may be formed integrally.

  In the above embodiment, the torch insertion hole 17a into which the tip of the welding torch 28 is inserted is formed on the outer peripheral edge of the lid 17 of the upper jig 2 ″. In this case, a torch insertion notch (not shown) into which the tip of the welding torch 28 is inserted may be formed on the outer peripheral edge of the lid body 17.

  In the above embodiment, the two jig units 2 are provided in the jig support mechanism 3. In other embodiments, one jig unit 2 is provided in the jig support mechanism 3. Two jig support mechanisms 3 each having one jig unit 2 may be provided side by side on the work surface 1a of the cabinet body 1.

It is a front view of the jig | tool unit which concerns on embodiment of this invention, and the circumference welding apparatus using the same. It is a partially cutaway side view of a jig unit and a circumferential welding apparatus using the same. It is a vertical front view of the jig | tool support mechanism which supports the jig | tool unit which concerns on embodiment of this invention, and a jig | tool unit. It is a side view of a jig unit and a jig support mechanism. It is a top view of a jig unit and a jig support mechanism. It is a vertical front view which shows the operation state of a jig unit and a jig support mechanism. It is an enlarged vertical sectional view of a jig knit. It is a front view of a torch turning unit. It is a partially broken side view of a torch turning unit. It is a partially cutaway rear view of a torch turning unit. It is a top view of a torch turning unit. It is a top view which shows the operating state of a torch turning unit. It is a longitudinal cross-sectional view of a top plate and a nozzle | cap | die in the state which joined the edge part of the nozzle | cap | die to the opening peripheral part of the top plate by the circumferential welding using the jig | tool unit and the circumferential welding apparatus. It is a longitudinal cross-sectional view of the top plate and the base in a state in which the end of the base is joined to the peripheral edge of the top plate by conventional circumferential welding.

Explanation of symbols

  1 is a cabinet body, 1a is a work surface, 2 is a jig unit, 2 'is an upper jig, 2 "is a lower jig, 3 is a jig support mechanism, 4 is a welding device, 11 is a lower clamp, and 11c is cooling. Water passage, 12 is a base support, 13 is an elastic body, 16 is an upper clamp, 16c is a cooling water passage, 16e is a stepped portion, 17 is a lid, 17a is a hole for inserting a torch, 28 is a torch for welding, and 50 is a welding torch. A top plate, 50a is an opening of the top plate, 51 is a base, 51a is a collar for positioning the base, G is a shield gas, and S is a shield gas space.

Claims (6)

  An end of an annular base (51) that forms an inlet or a ventilation port is inserted into the opening (50a) formed in the top plate (50) of the drum can or the container from the surface side of the top plate (50), and the top plate While the shield gas (G) is allowed to flow from the welding torch (28) toward the opening (50a) peripheral edge of the top plate (50) and the end of the base (51) from the back side of (50), a welding torch ( 28) swiveling and moving along the opening (50a) of the top plate (50) and the end of the base (51), and the end of the base (51) on the periphery of the opening (50a) of the top plate (50). A jig unit (2) used in a circumferential welding apparatus that is circumferentially welded by an arc in an atmosphere of a shielding gas (G), wherein the jig unit (2) has a top plate ( 50) and the base (51) inserted into the opening (50a) of the top plate (50) The upper jig (2 ') and the lower jig (2') are arranged above the lower jig (2 '), and the opening (50a) peripheral edge of the top plate (50) between the lower jig (2') It consists of an upper jig (2 ″) for holding and fixing the vicinity, and the upper jig (2 ″) is in surface contact from the upper surface side in the vicinity of the peripheral edge of the opening (50a) of the top plate (50) facing back. An annular upper clamp (16) that contacts in a state, and a torch insertion hole (in the upper clamp (16)) that is horizontally rotatable and into which the tip of the welding torch (28) is inserted at the outer peripheral edge ( 17a) or a notch for inserting a torch, and a shield gas (G) discharged from the welding torch (28) between the opening (50a) peripheral edge of the top plate (50) and the base (51) Shield the periphery of the welding area between the top plate (50) and the base (51) with shielding gas (G). And a disc-shaped lid (17) that forms a shield gas space (S) for the arc, and the lid (17) shields arc light while the welding torch (28) is swung. A jig unit that is configured to rotate in the upper clamp (16) together with the welding torch (28).   A step (16e) is formed on the inner peripheral surface of the upper clamp (16) so that the outer peripheral edge of the lid (17) is supported and slidably rotated. A hole for inserting a torch in the lid (17) (17a) or a state where the outer peripheral edge of the lid (17) is in surface contact with the step (16e) of the upper clamp (16) when the welding torch (28) inserted in the notch for insertion of the torch is turned. The jig unit according to claim 1, wherein the jig unit rotates together with the welding torch (28).   The jig unit according to claim 1 or 2, wherein a cooling water passage (16c) through which cooling water flows is formed in the upper clamp (16) of the upper jig (2 ").   The lower jig (2 ') is a ring-shaped lower clamp (supporting the top plate (50) by abutting in the surface contact state from the lower surface side in the vicinity of the peripheral edge of the opening (50a) of the top plate (50) facing back. 11), a base support (12) that is disposed in the lower clamp (11) so as to be movable up and down, and supports a base (51) inserted into the opening (50a) of the top plate (50), and the base support (12) An elastic body (13) that presses the positioning flange (51a) formed on the outer peripheral surface of the end portion of the base (51) by pressing it upward and presses the peripheral edge of the opening (50a) of the top plate (50) The peripheral edge of the opening (50a) of the top plate (50) is clamped and fixed by the lower clamp (11) and the upper clamp (16) of the upper jig (2 ″) and for positioning the base (51) Open the top plate (50) with the base (51a) by the base support (12) and the elastic body (13). (50a) fixture unit according to claim 1, claim 2 or claim 3, characterized in that a structure for pressing the peripheral portion.   The jig unit according to claim 4, wherein a cooling water passage (11c) through which cooling water flows is formed in the lower clamp (11) of the lower jig (2 ').   A large-diameter base (51) that forms an inlet from the surface side of the top plate (50) into the large-diameter opening (50a) and the small-diameter opening (50a) formed in the top plate (50) of the drum can or container. The end of the small-diameter base (51) that forms the end and the ventilation port is inserted, and the large-diameter opening (50a) of the top plate (50) from the back side of the top plate (50) has a large diameter. The end portion of the base (51) and the end portion of the small-diameter base (51) from the back surface side of the top plate (50) to the peripheral edge of the small-diameter opening (50a) are respectively shield gas (G ), A circumferential welding apparatus that is circumferentially welded by an arc, the circumferential welding apparatus comprising: a cabinet body (1) having a work surface (1a); and a work of the cabinet body (1). A large-diameter opening (50a) near the periphery of the top plate (50) disposed on the surface (1a) The jig unit (2) according to any one of claims 1 to 5, wherein the jig unit (2) supports the large-diameter base (51) inserted into the large-diameter opening (50a) of the top plate (50) while holding and fixing. In addition, the small-diameter opening (50a) of the top plate (50) disposed on the work surface of the cabinet body is sandwiched and fixed in the vicinity of the periphery, and the small-diameter opening (50a) of the top plate (50) The jig unit (2) according to any one of claims 1 to 5 and the work surface (1a) of the cabinet body (1) for supporting the inserted small-diameter base (51), A jig support mechanism (3) for supporting the jig unit (2) and a cabinet main body (1) are disposed in the cabinet body (1), and the shield gas (G) is discharged from the tip portion to increase the diameter of the top plate (50). Open the end of the large-diameter base (51) around the periphery of the opening (50a) with the shield gas (G). A welding apparatus (4) having a swivelable welding torch (28) for circumferential welding by an arc in an atmosphere, and a cabinet body (1) are disposed inside the cabinet body (1) to release shield gas (G) from the tip. A swivelable welding torch (28) for circumferentially welding the end of a small-diameter base (51) to the periphery of the small-diameter opening (50a) of the top plate (50) by an arc in an atmosphere of shielding gas (G) And a welding apparatus (4) provided with a circumferential welding apparatus.

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