JP2000176639A - Tig automatic welding method of boiler tubing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form the optimum penetration bead without any trouble to butting work in while simply executing a groove working by forming a groove shape as the V-groove and executing TIG welding from a primary layer to a finish layer so as not to entirely develop a root gap. SOLUTION: The groove shape at the butting portion of the boiler P is formed as V-groove and the TIG automatic welding is executed from the first layer to the finish layer so that the root gap RG becomes zero. In the case of being the tubing having 34.0-60.3 mm other diameter and 2.9-7.0 mm thickness, it is desirable to be 0-1.3 mm root face RF and 59-65 deg. angle θ. In this way, even in the case of developing little shifting on the level in the butting portion of the piping, when this shifting is within 20% of the thickness of the, TIG automatic welding can be executed. The welding condition is adjusted so as to be e.g. in the range of 0-300 A welding current, 0-30 V welding voltage, 0-1000 mm/min welding speed, 0-500 cm/min welding wire feeding speed and 0-50 l/min gas flow rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TI for a boiler pipe for automatically TIG-welding abutting boiler pipes.
G automatic welding method.

[0002]

2. Description of the Related Art When a conventional boiler pipe is butt-butted and welded on site, the groove shape forms a U-shaped groove, and then TIG welding is performed manually, or the first and second layers are manually formed by TIG welding. And then automatic welding.

In order to form a sound Uranami bead, for example, Japanese Unexamined Patent Publication No. Sho 59-163081 and Japanese Unexamined Patent Publication No. Sho 61-126971 disclose a case where TIG automatic welding is performed as shown in FIG. Describes that a V-groove and a gap are formed and TIG automatic welding is performed.

[0004]

However, in the case of forming a U groove and performing manual TIG welding, the processing cost of the U groove is higher than that of the V groove, and it takes time and effort to adjust the piping. However, in a normal boiler, the interval between adjacent boiler pipes is about 160 to 70 mm, so it is often impossible to perform construction from the back side, and welding is performed while checking the groove position using a mirror. In addition, there is a problem that the welding efficiency depends on the skill of the welder in terms of welding efficiency and welding quality.

[0005] In addition, even in the case of TIG automatic welding, it takes time and effort to butt the pipes, and in order to form a sound backwash bead in accordance with a change in the gap, it is necessary to control the wire feed amount and the like. There is a disadvantage that it must be.

Accordingly, the present invention provides a TIG automatic welding method for a boiler pipe, which can easily form a groove and can form an optimum backside bead without labor for abutting the pipes. It is.

[0007]

According to the present invention, there is provided a method for automatically welding a boiler pipe by TIG.
In the IG automatic welding method, the groove shape is V-groove, and the root gap is 0 and the TI is from the first layer to the last layer.
G Automatically welded.

In the above arrangement, weaving may be performed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a groove applied to the TIG automatic welding method of the present invention, (a) is an overall view showing a butt state of pipes, and (b) is an enlarged view of the groove. . The groove shape of the butt portion of the pipe P is a V groove shape,
The root gap (RG) is set to 0. Outside diameter 34.0-6
In the case of a pipe having a thickness of 0.3 mm and a thickness (t) of 2.9 to 7.0 mm, the root face (RF) preferably has a range of 0 to 1.3 mm and the angle (θ) has a range of 59 to 65 degrees.

According to the present invention, even if there is a slight deviation in the level of the butt portion of the pipe, if the deviation is within 20% of the wall thickness of the pipe, TIG automatic welding is possible.

The TIG automatic welding used in the practice of the present invention is not particularly limited, and TIG automatic welding used for known pipe welding can be used. TIG
The setting of the welding conditions for automatic welding is adjusted within the following range.

(1) Welding current: 0 to 300 A (both base current and peak voltage) (2) Welding voltage: 0 to 30 V (controlled by automatic voltage adjustment function) (3) Welding speed (trolley traveling speed): 0 1000mm /
min (4) Welding wire feeding speed: 0 to 500 cm / min
(Supply can be performed while synchronizing with the welding current.) (5) Gas flow rate 0 to 50 l / min The setting of welding conditions is usually performed by dividing one round (one pass) into four to five parts, but up to 24 parts. May be set.

FIG. 2 is a front view showing an example of a TIG automatic welding machine used for carrying out the present invention, and FIG. 3 is a side view of the same. The frame 2 fixed to the pipe by the clamp knob 1
A clamp 3 that holds the pipe P and rotates around the pipe P is provided. A TIG welding torch 6 having a tungsten electrode 4 and an inert gas inlet 5 such as argon is provided on the upper part of the clamp 3. The TIG welding torch 6 is provided with an inlet and an outlet for cooling water for cooling with water.

The clamp 3 is rotated about a pipe axis by a drive motor 7 provided on the upper portion of the frame 2, and the rotation of the clamp 3 causes the TIG welding torch 6 to rotate around the pipe along the groove.

Tungsten electrode 4 of TIG welding torch 6
, A wire guide 9 for supplying a wire 8 as a filler material is provided, and the wire guide 9 is connected to a wire feeder 1 from a wire reel 10 provided on an upper portion of the frame 2.
1 feeds a wire 8.

The TIG welding torch 6 is provided with a weaving device 12 for performing a weaving operation.

[0017]

Embodiment 1 FIG. 4 is a view showing a welding state by the TIG automatic welding method of the present invention, and FIG. 5 is a view showing a fixed position and a welding direction. The groove shape of the pipe having an outer diameter of 45 mm and a thickness (t) of 5.5 mm was machined so that the root face (RF) was 1.0 mm and the angle (θ) was 60 degrees. Then, after butting the pipes P, a part of both sides is fixedly welded by manual TIG welding.
After the fixed welding, TIG automatic welding is started.

The first layer was welded at a predetermined angle at five levels under different welding conditions. Table 1 shows the welding conditions for the first layer.

[0019]

[Table 1] Table 2 shows the welding conditions for the overlap of the final welding portion of the first layer.

[0020]

[Table 2] The second layer was welded by changing the welding conditions at four levels at a predetermined angle. Table 3 shows the welding conditions for the second layer.

[0021]

[Table 3] As a result after welding, the underside is clearly formed, the JIS1 grade is passed in the radiation transmission inspection, the base material is broken at the tensile strength of 470 N / mm ² in the joint tensile test, and the bending test is 180 degree bending, The welds were of good quality.

[0022]

According to the present invention, a groove can be formed more easily than a U groove, and an appropriate backwash can be formed without troublesome work of pipe fitting. Even with the same quality and efficiency, welding can be performed.

Further, in the conventional manual welding, it is impossible to set the root gap at 0, and the welding is performed with a gap of about the diameter of the welding material. However, according to the present invention, the root gap is set to 0. By increasing the arc concentration, TIG automatic welding can be performed using the V groove.

[Brief description of the drawings]

FIG. 1 shows a groove applied to a TIG automatic welding method according to the present invention, wherein FIG.
(B) is an enlarged view of a groove.

FIG. 2 is a front view showing an example of a TIG automatic welding machine used for carrying out the present invention.

FIG. 3 is a side view of the TIG automatic welding machine shown in FIG. 2;

FIG. 4 is a view showing a welding state according to the TIG automatic welding method of the present invention.

FIG. 5 is a diagram showing a fixed position and a welding direction.

FIG. 6 is a view showing a groove shape in conventional TIG automatic welding.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Clamp knob 2 Frame 3 Clamp 4 Tungsten electrode 5 Inert gas inlet 6 TIG welding torch 7 Drive motor 8 Wire 9 Wire guide 10 Wire reel 11 Wire feeder 12 Weaving device

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hideki Miyamoto 16-1, Tsukiji-cho, Yawatanishi-ku, Kitakyushu-shi Yamakyu Co., Ltd. Plant business headquarters (72) Inventor Eiki Tsuji 16-1, Tsukiji-cho, Yawatanishi-ku, Kitakyushu-shi Yamakyu F-term in the Plant Business Division of the Company Limited (reference) 3J023 EA02 FA03 GA03 4E081 AA14 AA15 BA27 CA11 DA11 EA12

Claims (2)

[Claims] 1. A method for automatically welding TIG by butt-butting boiler piping, wherein the TIG is automatically welded from the first layer to the last layer with a V-shaped groove and a root gap of 0. Automatic welding method. 2. An outer diameter of 34.0 to 60.3 mm and a wall thickness of 2.
For a pipe of 9 to 7.0 mm, the root face (R
F) is 0 to 1.3 mm, and the groove angle (θ) is 59 to 65.
The method for automatically welding TIG of a boiler pipe according to claim 1, wherein