CN105522259A - Welding method combining narrow gap argon arc automatic welding and submerged arc automatic welding for thick-walled pipes - Google Patents

Abstract

The invention relates to a welding method for combining narrow-gap argon arc automatic welding and submerged arc automatic welding of a thick-wall pipeline, which comprises the following steps of: the method comprises the following steps that firstly, end faces to be welded of a first pipeline and a second pipeline are close to each other, so that a vertical section of the first pipeline is attached to a vertical section of the second pipeline; step two, carrying out all-position welding on a circumferential seam between the vertical section of the first pipeline and the second pipeline until the outer ends of the second inclined sections of the first pipeline and the second pipeline form an inner welding seam of an arc surface; thirdly, performing automatic submerged arc welding on the circumferential weld between the first pipeline and the second pipeline outside the inner weld until the outer ends of the first inclined sections of the first pipeline and the second pipeline form an outer weld with an arc surface; the narrow-gap argon arc automatic welding is full-position welding, and a double-welding-wire positive and negative 360-degree welding circulation mode is realized. The invention has the advantages of reducing the energy of welding line, effectively reducing the sizes of welding seam and heat affected zone crystal grains, improving the welding quality and the first-time qualification rate of welding and reducing the labor intensity of welders.

Description

Welding method combining narrow gap argon arc automatic welding and submerged arc automatic welding for thick-walled pipes

technical field

The invention relates to a welding method combining argon arc automatic welding with narrow gap automatic welding and submerged arc automatic welding for thick-walled pipelines.

Background technique

At present, in the process of thermal power and nuclear power pipeline piping projects, there are a large number of welding of thick-walled pipelines. The traditional welding method uses manual argon arc welding + manual electrode welding to make a base, and the thickness of the base is 10-30mm. After bottom welding, the welding joint is dehydrogenated, preheated to the required temperature, and filled and welded to the cover surface by submerged arc automatic welding. Backing welding is carried out using traditional manual methods. Manual welding has a certain degree of flexibility, but on the other hand, the welding efficiency is relatively low, the work intensity of the welder is very high, the technical requirements for the welder are very high, and the quality of the weld is also very dependent on the welder, resulting in the poor pass rate of the weld. Stablize. Moreover, due to the large welding current, large heat input and heat input of traditional submerged arc automatic welding, the interlayer temperature is maintained in a relatively high range during the welding process, resulting in coarse grains in the weld seam and heat-affected zone, which affects the quality of the welded joint.

Contents of the invention

The purpose of the present invention is to overcome the above disadvantages and provide a welding method combining argon arc automatic welding with narrow gap automatic submerged arc welding for thick-walled pipes with high welding quality and high welding efficiency.

The purpose of the present invention is achieved like this:

A welding method combining narrow-gap argon-arc automatic welding and submerged arc automatic welding for thick-walled pipelines, characterized in that narrow-gap argon-arc automatic welding is used to weld the first and second pipelines to be welded arranged left and right. The right end face of the first pipe and the left end face of the second pipe have the same cross-section to be welded, and the cross-section to be welded includes the first oblique section, the first arc section, the second oblique section, and the second arc from outside to inside. section, horizontal section and vertical section, the lateral distance from the outer end of the first oblique section to the vertical section is 36mm, the angle between the first oblique section and the vertical section is 6°, and the first circle The radius of the arc section is 5mm, the angle between the second oblique section and the vertical section is 2°, and the radius of the second arc section is 3.5mm;

A welding method combining narrow-gap argon-arc automatic welding and submerged arc automatic welding for thick-walled pipes, comprising the following steps:

Step 1, bringing the end faces of the first pipe and the second pipe to be welded close together so that the vertical section of the first pipe and the vertical section of the second pipe fit together;

Step 2. Install a narrow-gap argon arc automatic welding machine on the first pipeline or the second pipeline, and perform all-position welding on the circular seam between the vertical section of the first pipeline and the second pipeline until the first pipeline and the second pipeline The outer end of the second oblique section forms an arc-shaped inner weld;

Step 3, performing submerged arc automatic welding on the circular seam between the first pipe and the second pipe outside the inner weld until the outer end of the first inclined section of the first pipe and the second pipe forms an outer weld of the arc surface;

Narrow-gap argon-arc automatic welding is all-position welding, which realizes the positive and negative 360-degree welding cycle mode of double welding wires,

In the process of all-position welding, according to the welding characteristics of different positions, the whole circle is roughly divided into four areas, namely flat welding position, downhill welding position, upward welding position and uphill welding position;

In flat welding position: base current 160A, peak current 260A, welding speed 85mm/min, wire feeding speed 90mm/min, arc voltage 9.2V;

In downhill welding position: base current 140A, peak current 260A, welding speed 80mm/min, wire feeding speed 80mm/min, arc voltage 9V;

In supine welding position: base current 140A, peak current 240A, welding speed 85mm/min, wire feeding speed 80mm/min, arc voltage 8.6V;

In the uphill welding position: the base current is 140A, the peak current is 260A, the welding speed is 85mm/min, the wire feeding speed is 85mm/min, and the arc voltage is 9V.

Compared with prior art, the beneficial effect of the present invention is:

The present invention adopts narrow-gap argon arc automatic welding for bottoming + submerged arc automatic welding for filling and covering: solving the current situation of manual welding for bottoming and realizing automatic bottoming welding. And combined with traditional submerged arc automatic welding to further improve welding efficiency. Weldments suitable for factory pipe prefabrication and high welding quality requirements. Therefore, the welding method of the present invention combining narrow-gap argon-arc automatic welding and submerged arc automatic welding of thick-walled pipes has the advantages of reducing the welding heat energy, effectively reducing the grain size of the weld seam and the heat-affected zone, improving the welding quality and the first pass rate of welding, And the advantages of reducing the labor intensity of welders.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a connection diagram of various accessories of the narrow gap argon arc automatic welding.

Figure 3 is a schematic diagram of the divisions of all-position welding.

Fig. 4 is a diagram showing the relationship between welding torch position, welding time and arc current during narrow gap argon arc automatic welding.

in:

The first pipe 1, the second pipe 2, the inner weld 3, and the outer weld 4.

detailed description

Referring to Fig. 1, the present invention relates to a welding method combining narrow-gap argon-arc automatic welding and submerged arc automatic welding for thick-walled pipes. A pipeline 1 and a second pipeline 2 are welded, and the right end surface of the first pipeline 1 and the left end surface of the second pipeline 2 have the same section to be welded, and the section to be welded sequentially includes the first oblique section, The first arc section, the second oblique section, the second arc section, the horizontal section and the vertical section, the lateral distance from the outer end of the first oblique section to the vertical section is 36mm, and the first oblique section and the vertical section The included angle between them is 6°, the radius of the first arc segment is 5mm, the included angle between the second oblique segment and the vertical segment is 2°, the radius of the second arc segment is 3.5mm.

A welding method combining narrow-gap argon-arc automatic welding and submerged arc automatic welding for thick-walled pipes, comprising the following steps:

Step 1, bringing the end faces of the first pipeline 1 and the second pipeline 2 to be welded close together so that the vertical section of the first pipeline 1 and the vertical section of the second pipeline 2 fit together;

Step 2. Install a narrow-gap argon arc automatic welding machine on the first pipeline 1 or the second pipeline 2, and connect the various accessories during welding (gas cylinder, welding power supply, hot wire power supply, water tank, control device, operation box, welding machine head, etc., the workpieces in Figure 2 are the first pipeline 1 and the second pipeline 2), and perform all-position welding on the circumferential seam between the vertical section of the first pipeline 1 and the second pipeline 2 Up to the outer ends of the second oblique section of the first pipe 1 and the second pipe 2 form arc-shaped inner welds 3 .

Step 3: Perform submerged arc automatic welding on the circular seam between the first pipe 1 and the second pipe 2 outside the inner weld 3 until the outer ends of the first inclined section of the first pipe 1 and the second pipe 2 form an arc surface Outer weld 4.

Narrow-gap argon arc automatic welding is all-position welding, using arc pressure sensing technology to control the arc length to be consistent up and down and on both sides, to realize automatic adjustment of electrode position, so as to achieve effective control of welding shape. Realize the positive and negative 360-degree welding cycle mode of double welding wire, and reduce welding joints. Compared with the traditional plus or minus 180 degree welding method, the efficiency is doubled. The arc current peak value/base value method is adopted during welding, the two side walls of the groove are welded by the peak current, and the peak current is taken when both ends stop, so that the base metal is fully penetrated; while the base value current is used during the electrode shaking process, so as to achieve The purpose of controlling welding heat input. Since the adaptability of automatic welding is relatively poor compared with manual welding, the requirements for the stability of process parameters and the control of the spatial position of the arc are very high. Moreover, the appearance quality of the previous weld formation has a great influence on the subsequent weld formation. The stable accuracy of process parameters and the accuracy of the arc directly affect the fusion quality between layers and side walls.

Considering all-position welding and process differences at different welding positions, the entire circumference area is controlled segmentally, and 4-point or 16-point input linear correction technology is used. In the process of all-position welding, according to the welding characteristics of different positions, see Figure 3, the whole circle is roughly divided into four areas, namely flat welding position, downhill welding position, supine welding position and uphill welding position. Along with the change of welding position, welding parameters such as peak/base value current, wire feeding speed, arc voltage, head walking speed (welding speed) need to be set differently at different positions of the circumference.

In flat welding position: base current 160A, peak current 260A, welding speed 85mm/min, wire feeding speed 90mm/min, arc voltage 9.2V;

In downhill welding position: base current 140A, peak current 260A, welding speed 80mm/min, wire feeding speed 80mm/min, arc voltage 9V;

In supine welding position: base current 140A, peak current 240A, welding speed 85mm/min, wire feeding speed 80mm/min, arc voltage 8.6V;

In the uphill welding position: the base current is 140A, the peak current is 260A, the welding speed is 85mm/min, the wire feeding speed is 85mm/min, and the arc voltage is 9V.

The above welding parameters are all linear changes.

Gun position base current peak current welding speed Wire speed arc voltage I/A I/A V (mm/min) V (mm/min) U/v Flat welding position (10:30~1:30) 160 260 85 90 9.2 Downhill welding position (1:30~4:30) 140 260 80 80 9 Overhead welding position (4:30~7:30) 140 240 85 80 8.6 Uphill welding position (7:30~10:30) 140 260 85 85 9

During the all-position welding process, the molten pool is mainly affected by arc force, surface tension and weight. In the flat welding position and uphill welding, due to the good welding shape, the welding specification can be appropriately increased. Under the action of arc heat at the downhill welding position, the molten pool has a downward trend, resulting in an increase in the actual welding thickness and an increase in the probability of incomplete penetration defects. By reducing the welding speed, reducing the arc voltage, and increasing the peak current can effectively increase the weld penetration. In the overhead welding position, especially the weld at the 6 o'clock position is affected by gravity, and the weld has the greatest tendency to collapse. By reducing the arc voltage and increasing the welding speed, the phenomenon of weld collapse can be effectively suppressed.

By setting the parameters of the whole welding process before welding, the welding parameters can be automatically adjusted in all positions according to the welding characteristics, so as to ensure the quality of welding forming.

Referring to Figure 4, we can see the trajectory of the position of the welding torch and the arc current at the corresponding time.

Claims (1)

1. A welding method combining narrow-gap argon-arc automatic welding and submerged-arc automatic welding for thick-walled pipes, characterized in that the first pipeline and the second pipeline to be welded arranged left and right are welded by narrow-gap argon-arc automatic welding, The right end surface of the first pipeline and the left end surface of the second pipeline have the same section to be welded, and the section to be welded includes a first oblique section, a first arc section, a second oblique section, and a second oblique section from outside to inside. Circular segment, horizontal segment and vertical segment, the lateral distance from the outer end of the first oblique segment to the vertical segment is 36mm, the angle between the first oblique segment and the vertical segment is 6°, the first oblique segment The radius of an arc segment is 5mm, the included angle between the second oblique segment and the vertical segment is 2°, and the radius of the second arc segment is 3.5mm; A welding method combining narrow-gap argon-arc automatic welding and submerged arc automatic welding for thick-walled pipes, comprising the following steps: Step 1, bringing the end faces of the first pipe and the second pipe to be welded close together so that the vertical section of the first pipe and the vertical section of the second pipe fit together; Step 2. Install a narrow-gap argon arc automatic welding machine on the first pipeline or the second pipeline, and perform all-position welding on the circular seam between the vertical section of the first pipeline and the second pipeline until the first pipeline and the second pipeline The outer end of the second oblique section forms an arc-shaped inner weld; Step 3, performing submerged arc automatic welding on the circular seam between the first pipe and the second pipe outside the inner weld until the outer end of the first inclined section of the first pipe and the second pipe forms an outer weld of the arc surface; Narrow-gap argon-arc automatic welding is all-position welding, which realizes the positive and negative 360-degree welding cycle mode of double welding wires, In the process of all-position welding, according to the welding characteristics of different positions, the whole circle is roughly divided into four areas, namely flat welding position, downhill welding position, upward welding position and uphill welding position; In flat welding position: base current 160A, peak current 260A, welding speed 85mm/min, wire feeding speed 90mm/min, arc voltage 9.2V; In downhill welding position: base current 140A, peak current 260A, welding speed 80mm/min, wire feeding speed 80mm/min, arc voltage 9V; In supine welding position: base current 140A, peak current 240A, welding speed 85mm/min, wire feeding speed 80mm/min, arc voltage 8.6V; In the uphill welding position: the base current is 140A, the peak current is 260A, the welding speed is 85mm/min, the wire feeding speed is 85mm/min, and the arc voltage is 9V.