CN115229310A - A kind of inner hole high penetration single pass gas tungsten shielded welding welding method - Google Patents

Abstract

The invention relates to an inner hole high-penetration single-pass gas tungsten shielded welding welding method, which adopts tube pair assembly and back-gas protection tooling. Inside the stainless steel tube, high-frequency pulses are used, supplemented by a mixture of helium and argon as the nozzle gas to improve the weld penetration. , During the all-position welding process, the welding parameters are adjusted in sections according to the welding position, and a butt weld of a 4mm wall thickness stainless steel pipe is completed. The invention adopts the high-frequency pulse gas tungsten gas shielded welding process to make the arc more straight, and combined with the protection of the helium-argon mixture gas, a relatively ideal welding seam shape is obtained, and a larger penetration depth is obtained. Through the single-pass welding method of the inner wall, combined with a small amount of wire filling welding, the problem of easy depression in the lower half of the inner wall is solved.

Description

A kind of inner hole high penetration single pass gas tungsten shielded welding welding method

technical field

The invention relates to a method for butt welding of stainless steel pipes in pressure vessels or pipeline equipment, in particular to a welding method for butt welding of stainless steel pipes and pipes by single-pass gas tungsten shielded welding with inner hole high penetration.

Background technique

In modern pressure vessels or pipeline equipment, the butt welded structure of stainless steel pipes is widely used. For such welds, gas tungsten arc welding is widely used to weld from the outside. Gas tungsten arc welding is to use the arc between the tungsten electrode and the workpiece to melt the metal to form a weld. During welding, the electrode does not melt, and the nozzle of the electric torch sprays inert gas to isolate the electrode and the molten metal from the air to avoid oxidation. Filler metal can be added or not added as needed during the welding process. However, some stainless steel pipe butt welds are located in the narrow space, and normal welding cannot be performed from the outside, and the welds can only be welded from the inside of the pipe.

Traditional inner hole welding is generally used for butt welding of heat exchange tubes and tube sheets, as shown in Figure 1. The wall thickness is generally not more than 2mm, and the inner diameter is generally not more than 25mm. Because the diameter is too small, the welding machine cannot install the wire feeding device, and the welding wire cannot be filled during welding. Because the space is too small, the heat dissipation capacity of the welding gun is limited, and it cannot exert a large current, so the penetration depth of the welding seam is very limited, generally no more than 2mm. When the current is larger, the depression in the lower half of the inner wall of the weld is more obvious.

At present, there are products with a diameter of 40-60mm and a wall thickness of 4mm. Due to the increased diameter, it is possible to add welding wire, but it cannot achieve a better angle wire feeding, and the wire feeding effect is not good. The thickness of the product nozzle reaches 4mm. If the traditional single-pass welding of gas tungsten arc gas shielded welding is used, it has exceeded the limit thickness of this welding method and cannot guarantee the penetration. For example, the butt weld of stainless steel pipe is completed by multi-pass welding with large groove inside the pipe. Because the inner diameter of the pipe is too small, the welding torch cannot be installed with a camera module, and it is impossible to observe and adjust the welding parameters and actions at any time. , Multi-layer multi-pass welding is prone to welding defects. In the case where the outside is not accessible, it is also very difficult to repair the weld defects. Therefore, it is necessary to develop a welding method with simple welding and high welding pass rate.

SUMMARY OF THE INVENTION

The invention aims to provide a single-pass gas tungsten-shielded welding method for inner hole high penetration, which solves the problem that the lower half of the inner wall is easy to sag, and improves the welding efficiency and welding quality through the single-pass welding method of the inner wall and the welding with a small amount of filler wire. .

In order to achieve the above-mentioned purpose, the technical scheme of the present invention is: a high-penetration single-pass gas tungsten-shielded welding welding method for inner holes, which adopts a pair of tubes to assemble and a back-gas protection tool, and the pair of tubes to assemble and the back-gas protection tool passes through the C type. The stainless steel pipe is locked and fixed by the fixture seat and the thread. When welding, the welding torch is inserted into the stainless steel pipe, and the high-frequency pulse is used together with the mixed gas of helium and argon as the nozzle gas to improve the weld penetration, and the inert gas passes through. The multiple uniformly distributed air holes in the assembly and the back gas protection tool of the tube group are evenly distributed to the back of the weld, and the back of the weld is effectively carried out with a small gas flow without taking too much heat of the weld. Protection; in the process of all-position welding, the welding parameters are adjusted in stages according to the welding position, and a butt weld of a 4mm wall thickness stainless steel pipe is completed.

Further, the described inner hole high penetration single pass gas tungsten shielded welding welding method, its specific steps are as follows:

(1) Set welding parameters;

(2) The two stainless steel pipes are aligned, and the assembly and the back gas protection tooling are fixed by the pipe group on the outside. After fixing, observe and confirm the welding seam alignment;

(3) The welding torch is inserted into the stainless steel tube, and the position of the tungsten electrode is confirmed through endoscope observation;

(4) Introduce inert gas into the pipe group assembly and back gas protection tooling;

(5) Start welding, remove the welding torch after welding, and remove the tooling.

Further, the pipe group pair assembly and back gas protection tooling include C-type clamps, clamp blocks, clamp bases, and screws; the clamp base and the C-type clamp are fixed to a C-type clamp base by welding, and the C-type clamp base corresponds to the C-type clamp base. The clamp is provided with a clamp block, and the upper end of the clamp block is connected with a screw screwed on the C clamp.

Further, the high frequency pulse frequency is 1000-2000 Hz, and the duty ratio is 20%-35%.

Further, in the mixed gas of helium and argon, the ratio of helium to argon is 8:2.

Further, in step (2), the welding seam is assembled as a tight assembly without gaps, and a chamfer of 0.5-1.0 mm and 45° is opened on the inner side of the stainless steel pipe as the welding seam groove.

Further, in step (3), it is necessary to simulate the welding motion to confirm that the tip of the tungsten electrode is always aligned with the center of the weld, and the starting position of the tungsten electrode welding is from 5 o'clock to 6 o'clock.

Further, in step (4), the inert gas is argon, and the flow rate of the back gas shielding gas is 3-5L/min during welding.

Beneficial effects of the present invention:

The invention adopts the high-frequency pulse gas tungsten electrode shielded welding (1000-2000Hz) process to make the arc more straight, combined with helium-argon mixed gas protection, to obtain a relatively ideal welding seam shape and a greater penetration depth. Through the single-pass welding method of the inner wall, combined with a small amount of wire filling welding, the problem of easy depression in the lower half of the inner wall is solved. A single-pass high-penetration gas tungsten-shielded welding method with simple welding, high welding efficiency and stable welding quality is realized.

The single-pass 4mm high-penetration gas tungsten shielded welding of the invention is suitable for inner hole welding of stainless steel pipes with small diameters (40-60mm), and has low welding difficulty, high welding efficiency and high welding pass rate.

Description of drawings

Figure 1 is a structural diagram of the inner hole welding of the heat exchange tube and the tube sheet;

2 is a schematic diagram of the present invention using the tube assembly to assemble and the back gas protection tooling to assemble and fix the tube and the welding position of the internal welding torch;

Figure 3 is a schematic diagram of the assembly of the pipe group and the back gas protection tooling;

Fig. 4 is a sectional view of the clamping block in Fig. 3;

In the picture: 1 is the tube pair assembly and back gas protection tooling, 2 is the welding torch, 3 is the stainless steel pipe, 1-1 is the C-clamp, 1-2 is the clamp block, 1-3 is the clamp seat, 1-4 is the screw.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

As shown in Figures 2 to 4, a welding method for welding stainless steel pipe and pipe butt welds using inner hole single-pass high penetration gas tungsten shielded welding, using pipe group pair assembly and back gas protection tooling 1, pipe group pair assembly The stainless steel tube 3 is locked and fixed by the C-type fixture seat and the back gas protection tooling 1, and the tube assembly and the back gas protection tooling 1 have a plurality of evenly distributed air outlets, and the inert gas passes through the above air outlets during welding. Evenly spread to the back of the weld, the back of the weld can be effectively protected with a small gas flow without carrying too much heat through the weld. During welding, high-frequency pulses are used and a mixture of helium and argon gas is used as the nozzle gas to improve the weld penetration. During the all-position welding process, the welding parameters are adjusted in sections according to the welding position, and a 4mm wall thickness stainless steel is completed after one welding. The effect of pipe butt welds.

The steps are as follows:

(1) Set welding parameters;

(2) The two pipes are aligned, and the assembly and the back gas protection tool 1 are fixed by the pipe group on the outside. After fixing, observe and confirm the welding seam alignment;

(3) The welding torch 2 extends into the inside of the tube, and the position of the tungsten electrode is observed and confirmed by means of an endoscope;

(4) Introduce an inert gas into the pipe group assembly and the back gas protection tool 1;

(5) Start welding, remove the welding torch after welding, and remove the tooling.

Preferably, the pipe group pair assembly and back air protection tooling 1 includes a C-type clamp 1-1, a clamp block 1-2, a clamp base 1-3, and a screw 1-4; the clamp base 1-3 and the C-type clamp 1-1 It is fixed as a C-type clamp seat by welding. The C-type clamp seat is provided with a clamp block 1-2 on the corresponding C-type clamp 1-1. The upper end of the clamp block 1-2 is connected to the C-type clamp 1-1. Screw 1- 4.

Preferably, the high-frequency pulse frequency is 1000-2000 Hz, and the duty cycle is 20%-35%.

Preferably, the helium:argon ratio of the mixed gas of helium and argon is 8:2.

Preferably, the welding seam assembly in step (2) is a tight assembly with no gap, and a chamfer of 0.5-1.0 mm and 45° is opened on the inner side of the pipe as the welding seam groove.

Preferably, in step (3), it is necessary to simulate the welding motion to confirm that the tip of the tungsten electrode is always aligned with the center of the welding seam, and the starting position of the tungsten electrode welding is from 5 o'clock to 6 o'clock.

Preferably, in step (4), the inert gas protector of the back gas protection tooling is argon gas, and the flow rate of the back gas protection gas during welding is 3-5L/min.

Example 1: The size is 60×4.0mm, the material is 304L stainless steel pipe butt joint, the inner side of the pipe is opened with 0.5mm, 45° chamfer. Pulse frequency: 1000Hz; nozzle gas:helium:argon ratio is 8:2.

Example 2: The size is 60×4.0mm, the material is 321 stainless steel pipe butt joint, the inner side of the pipe is opened with 0.5mm and 45° chamfer. Pulse frequency: 1500Hz; nozzle gas:helium:argon ratio is 8:2.

The technical key points of the present invention: (1) 1000-2000 high-frequency pulse, (2) the nozzle gas is a mixture of helium:argon, the ratio of helium:argon is 8:2, (3) a small amount of wire welding inside , (4) The fixed and gas protection structure of the back gas protection tooling.

Claims (8)

1. an inner hole high penetration single-channel gas tungsten shielded welding welding method, it is characterized in that: adopt pipe group to assembly and back gas protection tooling, pipe group to assembly and back gas protection tooling by C-type fixture seat and thread to stainless steel. The tube is locked and fixed. When welding, the welding torch extends into the stainless steel tube, and the high-frequency pulse is used with the mixed gas of helium and argon as the nozzle gas to improve the weld penetration. The inert gas passes through the tube group to assemble and back. There are multiple uniformly distributed air outlets in the gas shielding tooling, which are evenly distributed to the back of the weld, and the back of the weld is effectively protected with a small gas flow without taking too much heat from the weld; the all-position welding process According to the welding position, the welding parameters are adjusted in sections to complete a butt weld of a 4mm wall thickness stainless steel pipe. 2. The inner hole high-penetration single-pass gas tungsten shielded welding welding method according to claim 1, is characterized in that: the inner hole high-penetration single-pass gas tungsten shielded welding welding method, its concrete steps are as follows: (1) Set welding parameters; (2) The two stainless steel pipes are aligned, and the assembly and the back gas protection tooling are fixed by the pipe group on the outside. After fixing, observe and confirm the welding seam alignment; (3) The welding torch is inserted into the stainless steel tube, and the position of the tungsten electrode is confirmed through endoscope observation; (4) Introduce inert gas into the pipe group assembly and back gas protection tooling; (5) Start welding, remove the welding torch after welding, and remove the tooling. 3. The inner hole high-penetration single-pass gas tungsten shielded welding welding method according to claim 2, characterized in that: the pipe group comprises a C-type clamp, a clamp block, a clamp seat, and a screw for assembly and a back gas protection tool; The clamp seat and the C-type clamp are fixed into a C-type clamp seat by welding, and a clamp block is arranged on the corresponding C-type clamp in the C-type clamp seat, and the upper end of the clamp block is connected with a screw screwed on the C-type clamp. 4. The inner hole high penetration single-pass gas tungsten shielded welding welding method according to claim 2, wherein the high frequency pulse frequency is 1000-2000 Hz, and the duty ratio is 20%-35%. 5. inner hole high penetration single-pass gas tungsten shielded welding welding method according to claim 2, is characterized in that: in the mixed gas of described helium and argon, helium:argon ratio is 8:2. 6. The inner hole high-penetration single-pass gas tungsten shielded welding welding method according to claim 2, characterized in that: in the step (2), the welding seam is assembled as a tight assembly without a gap, and the inner side of the stainless steel pipe is opened by 0.5-1.0mm , 45° chamfer as the weld groove. 7. The inner hole high penetration single-pass gas tungsten shielded welding welding method according to claim 2, characterized in that: in step (3), it is necessary to simulate welding motion to confirm that the tip of the tungsten electrode is always aligned with the center of the weld, and the tungsten electrode starts to weld. The starting position is from 5 o'clock to 6 o'clock. 8. The inner hole high penetration single-pass gas tungsten shielded welding welding method according to claim 2, characterized in that: in step (4), the inert gas is argon gas, and the flow rate of back gas shielding gas is 3-5L/min during welding.

Images