JPS60174283A - Welding method - Google Patents

Abstract

PURPOSE:To prevent oxidation from arising in the part to be welded and to perform defectless welding by maintaining an inert atmosphere near the part to be welded by a shielding box. CONSTITUTION:An inert gas 22 is introduced through a gas introducing pipe 21 formed in an inert gaseous chamber 18 to maintain an inert gaseous atmosphere in a pipe hole part 11, a communicating hole 14 and a torch insertion path 17. The opening end of the path 17 of a shielding box 20 on the side to be welded is then closed by a light shielding plate 23 and a welding torch 25 is inserted into said path in such a way that the part of a tungsten electrode 24 is positioned above a tab plate 15. An arc 27 is generated between the electrode 24 and the plate 15 in an inert gaseous atmosphere while the transmission of welding heat to a pipe plate 12 is prevented by supplying a cooling liquid into a flow passage 16. A filler metal 26 is inserted into the arc 27 and the damaged part of the pipe hole part 11 is subjected to welding.

Description

[Detailed description of the invention] The present invention relates to a welding method.

FIG. 1 is an explanatory diagram showing the main parts of a tube sheet used in a heat exchanger. A large number of six tube portions 2 are formed on this tube sheet 1. Repairing the scratches 3 formed on the edges of the back chamber 2 and correcting the dimensions of the back chamber 2 have conventionally been carried out by a TIG-soluble method as shown in FIG. That is, the tab plate 4 is temporarily attached to the opening of the tube 6 part 2 with the scratch 3 on the tube plate 1, the welding torch 6 having the tungsten electrode 5 is inserted into the back chamber part 2, and the tungsten electrode 5 and the tag plate are inserted. Welding is performed by inserting filler metal 6 into the arc generated between 4 and 4. However, the air 7 inside the back chamber part 2
If the welded part is made of a material that is easily activated, such as titanium, oxidation occurs and a sound welded part cannot be obtained. Further, there was a problem in that the tab plate 4 had to be welded for temporary attachment.

The present invention has been made in view of these points, and provides a welding method that can perform sound welding by preventing the occurrence of oxidation and distortion of tube sheets in a completely inert atmosphere. This should be taken into consideration.

That is, one aspect of the present invention is to abut a cooling plate having a cooling effect on both sides of a welded body made of a tube plate in which a back chamber is formed such that its communication hole communicates with the back chamber, and Holding a tab plate near the back chamber within the communication hole,
A shield having an inert gas capacity around the torch insertion path connects the torch to the cooling plate so that the torch insertion path communicates with the communication hole. One open end of the channel is closed and a welding torch is inserted into the welded portion of the back chamber portion from the other open end.

This is a welding method in which an inert gas from the inert gas chamber is used to create an inert gas atmosphere inside the back chamber portion and the communication hole for welding.

Embodiments of the present invention will be described below with reference to the drawings.

First, as shown in FIG. 3, a cooling plate 13 having communication holes 14 is placed on the front and back surfaces of a tube plate 12 having a back chamber section 11, which is an object to be welded, so that the communication hole 14 communicates with the back chamber section 11. contact like this. The inner diameter of the communication hole 14 is set larger than the inner diameter of the back chamber part 11. A ring-shaped tab plate 15 is provided near the edge of the back chamber part 11 that contacts the tube plate 12 in the communication hole 14.
Insert. The end of the communication hole 14 remote from the tube plate 12 is
It has an opening with a larger diameter in the form of a forest. A cooling fluid flow path I6 is formed in the cooling patch plate 13 . Next, a torch insertion path is formed in the approximately truncated conical container along the axial direction of the container, and a shield box 20 is connected to the inert gas chamber 18 surrounding the torch insertion path 17 through a porous hole 19. It is inserted into the communication hole 14 so that the insertion path 17 communicates with the back chamber part 11 via the tab plate 15.

An inert gas 22 is introduced from a gas introduction pipe 21 formed in the inert gas chamber 18 to set the inside of the back chamber 11 and the inside of the communication hole 14° torch insertion path 17 to an inert gas atmosphere. Next, the open end of the torch insertion path 17 of the shield box 20 on the side to be welded is closed with a light shielding plate 23, and then the torch insertion path 17. Welding torch 25 is inserted through tube cutout 11 and above tab plate 15 so that tungsten electrode 24 is positioned. Next, the tungsten electrode 24 and the tab plate 15 are heated in an inert gas atmosphere while supplying a cooling liquid into the flow path 16 to prevent welding heat from being transmitted to the tube plate 12.
An arc is generated in between, and the filler metal 26 is inserted into the arc 27 to weld the damaged portion of the tube fire section 11.

As described above, according to this welding method, welding is performed while constantly being cooled by the cooling patch plate 13, so that distortion can be prevented from occurring in the back chamber portion 11 and predetermined welding can be performed. Moreover, since the shield box 20 creates an inert atmosphere in the vicinity of the part to be welded, welding can be performed while preventing oxidation of the part to be welded.

In particular, even when the part to be welded is made of abrasive materials such as titanium, molybdenum, and zircaloy, which are easily activated at high temperatures, oxidation can be prevented and sound welding can be performed. In addition, the tag plate 15 is connected to the communication hole 1 of the cooling patch plate 13.
4, the temporary fixing work of the tab plate 15 can be omitted.

Note that the welding situation can be easily observed through the light shielding plate 23. Further, the melded gas 28 is also ejected from the welding torch 25.

As explained above, according to the welding method according to the present invention, it is possible to prevent oxidation and distortion of the tube sheet in a completely inert atmosphere and perform sound welding.

[Brief explanation of drawings]

FIG. 1 is an explanatory view showing the main parts of a tube sheet, FIG. 2 is an explanatory view showing a conventional welding method, and FIG. 3 is an explanatory view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 11... Back chamber part, 12... Tube plate, 13... Cooling plate, I4... Communication hole, 15... Tab plate, 16...
... Distribution hole, 17... Torch insertion path, 18... Inert gas chamber, 19... Porous, 20... Shield box, 21... Gas introduction pipe, 22... Inert gas ,2
3... Light shielding plate, 24... Tungsten electrode, 25-
...Welding torch%26...Filler metal, 27...
·arc. 28...Shield Gae. 114 sub-agents Patent attorney Takehiko Suzue Continued from page 1 ■Inventor Yoshio Hashimoto 2-1-1 Shinhama, Arai-cho, Takasago City Mitsubishi Heavy Industries, Ltd. Takasago Research Center

Claims (1)

[Claims] A cooling plate having a cooling effect is brought into contact with both sides of the object to be welded, which is made of a tube plate having a back chamber formed therein, so that its communication hole communicates with the back chamber, and the A shield that holds a tab plate near the back chamber and has an inert gas chamber around the torch insertion path? Connect the torch to the cooling plate so that the torch insertion path communicates with the communication hole, close one open end of the torch insertion path, and weld to the part to be welded of the backlight part from the other open end. A welding method characterized by inserting a torch and performing welding by creating an inert gas atmosphere in the back chamber portion and the communication hole using inert gas from the inert gas chamber.