JPH07185805A - Gas shielded welding method - Google Patents

Abstract

PURPOSE:To completely eliminate weld defects by sealing a small hole after ending hermetic welding. CONSTITUTION:An insertion part 4 of an aluminum terminal 3 is inserted into an aluminum pipe and while gaseous argon 8 to bring a welding torch 6 for MIG welding near to a contact part is blowing, the front end of an aluminum welding wire 7 is pressed to the contact part to form an initial weld zone 9. Further, a build-up weld zone 10 is formed. The small hole 11 is, thereupon, previously formed in a position distant from the weld zones 9, 10. This small hole 11 is sealed after the end of hermetic welding 9, 10. As a result, the completely hermetic weld zone is obtd. by the extremely easy and simple means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for welding a metal, such as an end portion of an aluminum pipe portion of a pipe type jumper device for a power transmission line, which is to be hermetically finished.

[0002]

2. Description of the Related Art As a jumper device used in an ultrahigh voltage power transmission line, for example, an aluminum pipe having an outer diameter of 120 mm and a length of 4 to 13 m, to which aluminum terminals are attached, is known.

As a method for this attachment, a method has been tried in which two aluminum terminal tips are respectively inserted into pipe ends and the outer peripheral portion of the insert and the pipe ends are MIG welded using a shield gas such as argon. There is.

[0004]

However, when this welding is actually carried out, the defective welding rate is very high, and there is a practical problem.

[0005]

Detailed observation of the state of occurrence of defective welding reveals that, of the two ends of the pipe, there is almost no defect at the side end to be welded first, and it is concentrated at the side end to be welded later.

With respect to the occurrence of the defect, it was confirmed that even at the side edge to be welded later, a small portion that cannot be welded was produced at the end of the buildup, which is the last stage, and the solution was taken. .

That is, in the welding of the side end to be welded later, the inside of the pipe becomes completely sealed as the welding work progresses. Moreover, since the air in the airtightness gradually expands due to the welding heat, at the final stage of the build-up, air is blown out from the small portion where welding is in progress, and a shielding gas such as argon for welding this portion is used. It was inferred that the welding did not reach the welding progressing part, which could cause welding failure.

Based on the reasoning, when a small hole for ventilation was provided in a part of the pipe away from the welded part and welding was performed,
Welding defects could be completely eliminated. The small holes for ventilation are sealed by any means such as welding or embedding after the welding work is completed.

[0009]

[Example] In FIG. 1, 1 is an outer diameter of 120 mm and a wall thickness of 8 to 15 m.
An aluminum pipe for a jumper device having a length of m and a length of 8 to 13 m is supported by the support base 2 and welded while rotating in the direction of the arrow. 3 is an aluminum terminal, 4 is an insertion portion to be inserted and welded to the end of the pipe, 5 is a mounting hole, 6 is a welding torch for MIG welding, 7 is an aluminum welding wire to be drawn out, and 8 is spouted from the outer peripheral portion of 7. Argon gas.

FIG. 2 is an enlarged vertical side view showing a part of the portion of the aluminum pipe 1 shown in FIG. 1 where the insertion portion 4 of the aluminum terminal 3 is inserted and welded. FIG. 2 is an explanatory view of the pipe 1 having the other end already welded and the side end to be welded later.

Insert the insertion portion 4 of the aluminum terminal 3 into the end of the aluminum pipe 1, bring the welding torch 6 for MIG welding close to the contact portion 1 and 3 to be joined, and blow the argon gas 8 while welding the aluminum welding wire. 7 The tip is applied to the contact portion to form the initial welded portion 9. While rotating 1 and 3 as shown by the arrow, the aluminum welding line 1 is fed out to advance the above-mentioned welding, so that the initial welded portion 9 is formed on the entire circumference of the contact portion of 1 and 3 first.

At this stage, the local temperature rise of the aluminum pipe 1 due to the welding heat is also slight, so that the initial welded portion 9 is formed almost uniformly. However, when the welding is further advanced to form the build-up welded portion 10, the local temperature rise gradually increases and accumulates. Therefore, the welding of the aluminum terminal at the other end in the aluminum pipe 1 The air sealed by the initial welding portion 9 gradually expands due to heating.

As a result, in the final stage of formation of the overlay welding portion 10, when the initial welding portion 9 is heated by welding for the final welding, expanded air is ejected from the heated and melted portion, and the argon gas 8 is applied to that portion. It will not reach and welding defects will occur.

Reference numeral 11 in the drawing denotes a small hole having a diameter of 7 mm which is provided in advance at a position 10 cm away from the weld end of the aluminum pipe 1 in order to prevent the ejection of air. In the embodiment provided with this small hole, The initial and overlay welding performed according to the above procedure could be smoothly performed without any trouble, and a completely hermetically welded portion could be obtained.

Although the small hole 11 is welded and sealed after completion of the welding of the aluminum terminal, this sealing may be performed by another method such as embedding. The position of the small holes,
It goes without saying that the size and number can be appropriately selected depending on the size and shape of the object to be welded.

[0016]

The present invention is capable of completely eliminating the conventional welding defects by previously forming small holes in the object to be welded. It is possible to achieve the effect.

[Brief description of drawings]

FIG. 1 is a schematic side view for explaining an outline of a welding method in an example.

FIG. 2 is a vertical cross-sectional side view showing an enlarged part of the welded portion in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Aluminum pipe 2 Support stand 3 Aluminum terminal 4 Aluminum terminal insertion part 5 Aluminum terminal mounting hole 6 MIG welding torch part 7 Aluminum welding line 8 Argon gas 9 Initial welding part 10 Overlay welding part 11 Provided on the aluminum pipe Small hole

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Sakai 2 No. 20 Toda, Kitagawara, Itami City, Hyogo Prefecture Asahi Metal Seiko Co., Ltd.

Claims (1)

[Claims] 1. In welding of a metal for finishing in a hermetically sealed state,
A gas shield welding method characterized in that a small hole is provided in advance at a position apart from the welded portion, and the small hole is sealed after the closed welding is completed.