SU707715A1 - Method of arc welding into narrow joint - Google Patents

Description

(54) METHOD OF ARC WELDING NARROW CUT

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The invention relates to welding, more precisely to arc welding with coated electrodes, which is performed in narrow, so-called slit-like grooves. The bevel angle of the edges of such cuts is about 4-7 ° with a thickness of welded parts up to 80-100 mm. Naibo. The use of cutting with such parameters was found at the evarke of non-rotating joints of pipelines, for example, pipelines of the primary circuit of nuclear power plants.

The methods of arc welding with coated electrodes are known with moving the electrode in the groove along various paths 11. Manipulating the electrode in the groove is performed to improve the formation of a seam. Drawing quality and labor productivity. its thickness, cutting depths, etc.

There is also known a method of arc welding with a rectilinear displacement of the electrode in the groove 2.

OcpiaKO known method has low productivity and does not always ensure high quality of the welded joint.

The purpose of the invention is to improve the quality of the welded joint by reducing the deformation and adjusting the formation of the seam, as well as increasing the productivity.

To achieve this goal, during welding, in narrow cuts with a straight line displacement of the electrode, along the cuts, the electrode is displaced with a delay and with a delay at each stop for 2.0-2.5 sec. in the direction of its movement at an angle of 5-8 ° from the vertical without

S transverse displacement of the working end of the electrode and hold the electrode in extreme positions for 0.5-1.0 s.

When the electrode moves in a straight line along the axis of the groove, it is made to melt

Claims (2)

Q of the underlying metal (the main or previously applied weld). At the same time, due to the heat conduction, the temperature of the edges of the groove is slightly increased, and also the gravitational pressure of the pressure gauge to the base} 1 is provided. By tilting the electrode by 5-8 ° after each i of the next step and its short (about 0.51, 0 sec) exposure in this position ensures a smooth transition from the cutting edge to the weld metal. The proposed sequence of displacement and manipulation of the electrode provides sufficient for guaranteeing the quality of the welded joint alloying of the filler metal with the cutting edges and underlying layers at a low heat input. Due to this, a thermal zone of small extent is formed, which contributes to the reduction of the deformation and the decrease in the level of residual stresses in the welded joint. The deviation of the electrode from the vertical position allows you to adjust the formation of the seam and slag, to create a smooth transition from the edges to the seam. When the electrode is tilted by 5-8 ° and fixed in an inclined position for a tenth of a second, a flat or slightly concave seam surface is created. This shape of the seam facilitates the removal of slag from narrow cutting. FIG. 1 shows the electrode in a narrow space of the non-swiveling joint of the pipeline; in fig. 2 - inclined laid} electrode in a narrow cutting; in fig. 3 - narrow cutting in plan, dots indicate the steps of the movement of the electrode in it. Example 1. Manual arc welding of the joints of steam pipelines made of 12H1MF steel with a diameter of 133 mm and a wall thickness of 17 mm was carried out. Welding was performed on a backing ring into a groove with a bevel angle of 5 ° and a width of 6.0 mm of gap in the root of the seam. The first two layers were made with TML-3 electrodes with a diameter of 3 mm, the subsequent layers with TML-3 electrodes with a diameter of 4 mm. During each passage, the electrode was moved in steps of 0.8 in the bottom of the electrode meter and tilted in both directions by about an angle b. The shutter speed in the extreme position was about 0.8 sec. The total duration of each stepwise displacement of the electrode was about 2.2 seconds. Timekeeping was performed using a manual stopwatch, and the above data is averaged. Example 2. Manual arc welding of the joints of steam lines from 15H1MF steel with a diameter of 355 mm and a wall thickness of 50 mm was carried out. Welding was carried out on the bottom ring in the cutting with jTnoMf bevel edges 7 and the gap width in the root of the seam is 6.5 mm. The first 7 and 4 layers were made with TMJI-3 electrodes with a diametre of 3 mm, the subsequent scoops with ML-3 electrodes with a diameter of 4 mm. On each pass, the electrode was moved with a tag of 1.0 to the diameter of the electrode and was tilted in both directions and an angle of about 8. The shutter speed in the extreme positions was approximately 1.0 sec. The consistency of each step of movement left about 2 seconds. Timekeeping was based on a manual secundomera, and the data presented are averaged. It has been found that when welding these joints, the labor productivity of welders as compared with the examples of the first method is higher than the method. It increases by 20-25%, and the quality of the welded joint is noticeably higher. Compared with npHMeHHeivibiMH at present, the method of welding aggravating the proposed method provides an increase in productivity by approximately 15-25%, reduces the consumption of electrodes approximately by 15-35%, reduces the power consumption and the consumption of the base metal when preparing the edges. Only in the Soviet Union’s Ministry of Energy and Electricity Systems, the annual economic effect from the introduction of the proposed method will be about 1 million. The invention of the method of arc welding is a narrow cutting with coated electrodes with a direction of movement of the electrode along the cutting, about 10 mm and so that, in order to improve the quality of the welded joint by reducing the strain and adjusting the formed weld, also increases the drive speed, the electrode is moved in a stepwise manner with a delay at the stopping point for 2.0-2.5 seconds, and in k; to, from these points, the electrode is deflected perpendicular to the direction of its movement in both directions. from vertical without pone the river displacement of the working end of the electrode to hold the electrode in extreme positions for 0.5-1.0 sec. Sources of information taken into account during the examination 1. Kakhovsky P.I. Elektrodz ova welding steels. Kiev, Naukova Dumka, 1975, p. 393, fig. U1.1. 2.Ka; Shvsky N. I. Electrodu1-ov svorka steel. Kiev, Nzukova Dumka, 1975, p. 426, fig. U} 1.2.