SU1493415A1 - Method of electric welding of thick-sheet metal - Google Patents

Abstract

The invention relates to welding production and can be used in single-pass welding of butt joints of thick sheet metal of any length without edge cutting. The purpose of the invention is to increase the productivity and quality of welding. During periods of electrode movement in the welding direction and backward with a speed 1.2-1.5 times greater than the speed of its movement in the welding direction, current density and arc voltage are controlled from their minimum to maximum values at specified intervals. time and the subsequent reduction of their values from the achieved maximum values. During the period of movement of the welding electrode in the welding direction, the process is carried out in the initial period of time на ₁ at the minimum current density with a smooth increase in the period of time рав ₂ equal to from 0.12-0.16 thickness of the metal to its maximum value and maximum density current in the period of time Τ ₃ , and when the electrode moves backward, the current density is stepwise regulated, while in the period of time рав ₄ equal to 0.03-0.06 of the metal thickness, it decreases from the maximum value to the value of I ₁ with its subsequent increase to I ₂ during vre tim Τ ₅ and decreased to a minimum value in a time period equal to ₆ 0,03-0,6 Τ metal thickness. When the welding electrode moves in the welding direction, the process is carried out in a period of time Τ ₁ +1/2 Τ ₂ at the base voltage on the arc, followed by an increase in the remaining time period 1/2 ₂ to the maximum value and maximum voltage in period 4 / 5 Τ ₃ , and in the remaining period of moving the welding electrode back and forth - in the time period 1/5 Τ ₃ + ₄ - reduce the arc voltage to the minimum value and then increase it to the intermediate and base value, respectively Τ ₅ and Τ ₆ . The regulation of the welding current density and arc voltage ensures effective arc penetration and satisfactory formation of the root part of the seam. 2 ill., 2 tab.

Description

The invention relates to electric arc welding and can be effectively used with a single pass weld of butt joints of thick sheet metal (from 40-80 mm) of any length without edge cutting.

The purpose of the invention is to increase the arc melting capacity, process productivity and improvement of the formation of the root part of the seam.

FIG. Figure 1 shows the graphs of the nature of the change in the density of the welding current, voltage across the arc, and the speed of movement of the trolley of the welding machine; Fig, 2 is a diagram of the proposed method of welding.

The welding process is carried out at cyclically varying mode pairs. The welding cycle starts with the minimum density of the welding current and initial (base) voltage values on the arc Ug with the speed of the electrode moving along the step along the welding direction VJ, J. to step L (from point 1 to point 4, fig. 2), while the welding arc moves relative to the plane of the weld; my edges according to a complex law; During time 1, it burns on the surface of the joined ends of the product (t. 1-2) then as it grows welding current density from to due to an increase in the electrode wire feed rate and voltage1: on the arc (points 2-3 and 2-2, respectively, Fig. 1), for a period of time f, the arc column gradually deepens (from point 2 to points 3, Fig. 2) on the thickness of the product to be welded. The smooth deepening of the Ugie provides precisely nonsynchronous in time (Increase in current density and, for example, xyne on the arc in period i (growth i lags behind growth and rt by).

“Lks 1 max period) the root portion of the seam (from t. 3 to t. 4, fig. 2). In the final section Cj, the carriage of the welding machine is reversed and moved back at the speed V n.r.i to step L (from t. 4 to t, 2, fig. 2) during

4 5 form the middle part of the seam. In this case, in section C, the current density is reduced from i m KS and 1 and the voltage across the arc from (respectively

(points 4-5 and, fig. 1). For bo

more effective quenching of the average heat input of the process during this period of time, the desiccation of U o from U to begins earlier (by l / 5f) than the current density

With further movement of the head of the apparatus with the speed Vn.ri in the period of time C j, a simultaneous increase in the current density from i to i (TO 5-6, Fig, 1) and the voltage across the arc from and to industrial (t = 5-6 , Fig. 2). In the period of time -O, a simultaneous decrease in all regulated

the mode parameters to their base (initial) value, corresponding to the time period of the process cyclogram: current density from i to i, and the voltage across the arc from. to (see Fig. I, respectively, vol. 6-7 (1). The arc comes to the surface of the welded edges (t. 6-7 (1), Fig. 2), and at a subsequent point in time (-G ) it forms the front surface

So in periods,

And fj, the edges being welded are warmed up, a smooth deepening of the arc into the base metal, guaranteed penetration and high-quality formation of the root section

suture, and in periods 2, G

and

- defect-free formation of the middle part of the weld metal by the corresponding

step cycling of current density and arc voltage Initial mode parameters, such as i ,, i ,, V, p and Uj, ensure steady arc burning on the surface of the edges being welded and satisfactory formation of the front part of the seam. This completes one welding cycle, the amount of which depends on the length of the product being welded. The first and last welding cycles are performed on additional planks in order to guarantee the fusion of the initial and final sections of the seam. Welding is performed on standard equipment.

(welding machine A-1401, rectifier welding type VDU-1601) with connection to the electrical circuit of the welding machine of a programming device, wired by its parameters of the process mode in order to ensure the specified welding cycle,

Example: Welding a UXSND steel plate with a size of 40 × 40 500 mm is produced under laboratory conditions.

 In two versions: with welding currents equal to IMMH 500 A; 1 - 1000 A; Ij 1300 A; 1 „„ “e

 -1500 A and arc voltages equal to Us 60 V; and „„ „55 V; U 58 V; U (V (c, Kc 65 V). Samples for welding are collected with a gap with the help of extra strips. Welding is carried out with Sv-Zvga wire 1) Ω 4 mm

“Direct current of reverse polarity on a flux cushion, As the welding and lining flux using flux AHB. Efficiency

U934I56

 1.4 s produce a simultaneous decrease in the current density from i j to i / them and an increase in the voltage across the arc from

 to 5-60 V to their original values. This ends one welding cycle with mode parameters corresponding to the start of the next welding cycle,

Thus, the regulation of the welding current density, arc voltage, welding speed and direction of movement of the welding head (automatic) provides both

20

The arc penetration and early-penetration capacity of the arc to the thickness of the root part of the seam is compared with the common plumbing gauge with an accuracy of 0.5 mm on the cross-sectional sections by comparing the welding variants. The welding process starts with a minimum current density of 40 A / mm and a base voltage on the arc U § 60 V. Its duration is S - 6.5 s. Then with the help of a programming device increase the aisle 1, and the satisfactory formation of the root part of the seam. The welding method with additional regulation of current density and voltage on the arc in combination with reciprocating (without residues) movements of the welding head (electrode) during the corresponding periods of time provides a higher

25 what arc melting ability and uniform formation of the seam. The increase in the penetration depth of the base metal by controlled cycling of the regime parameters is associated with

the welding current from i

mk n

BEFORE

lix 119 A / mm in time G 5 s and the voltage across the arc from U g to Tchmo "ks 65 V in time (2.5 s. The increase in current density advances in time the increase in voltage on the arc on s. With the achievement of maximum density current and its power supply for 6.5 s support the maximum and the voltage on the arc

Low current density

Mdkc 65 V for 4/5 C j

following

from i l ksdo i, 80 A / mm is ahead of the initial stage of reducing the voltage by 1 / 5C;)

not on the arc from

Moving the welding head (electrode) forward in the direction of welding in a period of time C + h-C, 18 s is carried out with a speed of V JJ p 26 m / g at a step L 130 mm, and while mixing it back in a period of time I} + 5 with a speed of V g 4 35 m / h per pitch L 65 mm. A decrease in the welding current density from to i is carried out for a time of i) 1.4 s, and the voltage across the arc from U TO min. Time is 1/5 2.7 s. The current density is then increased from i to i and the voltage across

the arc from and “„ „55 V to and“ rum for 0 4 s. During the period

58 V

i

effective arc penetration

Period 1 and satisfactory formation of the root of the seam. The welding method with additional regulation of current density and voltage on the arc in combination with reciprocating (without residues) movement of the welding head (electrode) during the corresponding periods of time provides a higher arc melting capacity and uniform formation of the seam. The increase in the penetration depth of the base metal by controlled cycling of the parameters of the regime is associated with

change in the thermal characteristics of the arc and its gas-dynamic pressure on the bath melt, which is explained by an increase in the average heat input of the process

„

To assess the quality indicators of welded joints, the mechanical characteristics of the metal of different zones of the joints

completed in the indicated ways. Samples for static and impact tests are cut out from welded plates in accordance with the requirements of GOST 6996-66. The longitudinal axis of cylindrical specimens with a diameter of 3 mm coincides. em with the direction of the longitudinal axis of the seam, and the location of the axis is chosen

on template macroshlfft. Static tensile tests were carried out on an IM-4R machine with a recording of stretch diagrams. Toughness tests (impact bending) were used to make Type VI samples. Marking for an incision is also made on macroschemes.

The results of the evaluation of the mechanical characteristics of the weld metal and the toughness of the welded joint are presented in Table 1 and 2.

As can be seen from the table, 1 and 2, all mechanical characteristics and 10XSND steel joints are not lower than the specifications for this steel weld. Weld seam, made by the proposed welding method, without pores and slag inclusions, monolithic, with a peculiar ) the nature of crystallization. The proposed welding method is characterized by increased melting ability.

Claims (2)

Formula for isobten E-method of arc welding tol-. table metal, in which the electrode is periodically moved by ar, equal to 20 to 40 diameters of the electrode in the direction of welding, and back and a step equal to 10 to 20 diameters of the electrode n, is h; a and c by the fact that, in order to increase production edvN1 I quality by increasing the melting capacity of the arc and ulu 1shen1-g forming 25 root root of the seam, in period 1, moving the electrode in the direction of welding, i i 0.13 -. 0.17 thickness of the metal being welded, the process is carried out at the minimum, d) current density c. by graduating from it in the period of time V, the composition of the proposed method AO 600-613 480-512 25.0 62.0 505 Note 1. Mechanical characteristics of the base metal (p. 10HSND) z 520 MPa ;; сГ 19% i & T.400 MPa; v 61% 2; Above the line - limit values of mechanical; properties, below the line are average values of five tests. The thickness of the metal is 0.12–0.16 thickness of the metal, then during time C, the process is carried out at the maximum current density, and when the electrode is moved back within the time period C equal to 0.03–0.06 of the metal thickness, the current density is reduced to 23–27 metal thicknesses, followed by its increase to 30–3.5 mm thick metal thickness for a time fr of 0.01–0.02 metal thickness, and then decrease to a minimum value during a time period C €. , at the same time, over a period of + 0.5 ° C, the welding process is carried out at the base voltage on the arc with its subsequent increase in the period of time 0.5 i. up to a maximum value of 1.07-1.1 base voltage at maximum voltage in the period of the A / C, and in the remaining period l / Sc j + t reduce the voltage to a minimum value of 0.9 - 0 , 93 values of the base voltage, with its subsequent increase in the period of time 1} y to a value of 0.95 - 0.98 of the value of the base voltage, and then in period 1 to the value of the base voltage. Table 1 The proposed method 40 Notes, 1. Above the line are limit values. impact strength, below the line - the average values of five tests, 2. The impact viscosity of the base metal at the test temperature is 50 J / cm. table 2 56-68 48-56 BT 50 2