SU1542737A1 - Method of terminating the process of automatic consumable electrode welding - Google Patents

Abstract

The invention relates to electric fusion welding, preferably automatic submerged arc welding, and can be used in welding ring seams, sheet blanks with intersecting seams, as well as in high-speed welding with lead strips. The purpose of the invention is to improve the formation of the weld at the end of welding on the lead bars, eliminating the crater and saving energy when welding without lead bars. At the end of welding at the moment when the welding head approaches the distance from the edge of the welded joint equal to 0.1 - 1.0 of the nominal bath length, the welding process is carried out in a pulsed mode. The power of the welding heat source in the pause is reduced to zero, the duration of the pause is taken @ 0.1 - 0.9 duration of crystallization of the metal bath. In a pulse, the power is increased to the nominal, the pulse duration is maintained equal to the duration of increasing the width and depth of the bath to their nominal dimensions. In the case of welding without terminal strips, when the welding electrode approaches the end of the joint, it is stopped and the electrode melting is continued in a pulsed mode for 2 ... 4 periods of impulses and pauses. In this case, the feed rate of the melting electrode is reduced to 0.1 - 0.3 of its nominal value, and the voltage is maintained at 0.1 - 0.9 of the nominal voltage.

falcons alex

Description

(21) 4382566 / 31-27

(22) 12/28/87

(46) 02.15.90. Bul № 6

(71) Electric Welding Institute. E. O. Paton

(72) D. And Dudko, V.S. Sidoruk, B.V. Danilchenko, O.L. Bukhar

and N. In Gorbenko

(53) 621.791 75 (088.8)

(56) USSR Author's Certificate No. 1175636, cl. On 23 K 9/16, 1984.

For Japan No. 56-102380, cl. B 23 C 9/16, 1981

(54) METHOD FOR ENDING THE PROCESS OF AUTOMATIC WELDING BY MELTING ELECTRODE

(57) The invention relates to electric fusion welding, preferably automatic submerged arc welding, and can be used in welding ring seams, sheet blanks with intersecting seams, as well as high-speed welding with lead bars. The purpose of the invention is to improve the formation of the weld at the end of the welding on the lead bars, the elimination of the crater and save electricity when checking without lead bars.

The invention relates to electric fusion welding, mainly automatic submerged-arc arc welding, and can be used in high-speed welding, where increased metal consumption on lead-outs is unavoidable due to the long length of the metal bath, as well as in welding of sheet blanks ("cards) with intersecting seams. and when welding ring seams where the use of exit strips is not possible.

The purpose of the invention is to improve the formation of a weld at the end of welding at the end. When welding is finished when the welding head is at a distance of 0.1-1.0 times the nominal length of the weld joint, the welding process is pulsed. The power of the welding heat source in the pause is reduced to zero, the duration of the pause is 0.1-0.9 duration of the crystallization of the metal bath. In a pulse, the power is increased to the nominal, the pulse duration is maintained equal to the duration of increasing the width and depth of the bath to their nominal dimensions. In the case of welding without terminal strips, when the welding electrode approaches the end of the joint, it is stopped and the electrode melting is continued in a pulsed mode for 2-4 periods of pulse and pause. In this case, the feed rate of the melting electrode is reduced to 0.1-0.3 of its nominal value, and the voltage is maintained at 0.1-0.9 of the nominal voltage of the arc or electroslag process at a given wire feed rate. The method saves metal on the terminal strips, which is especially effective when welding titanium and other expensive metals. 2 h. item f-ly, 2 ill.

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edges, the exclusion of the crater and save electricity when welding without lead bars.

FIG. 1 shows a sequence diagram of the change in the power of the welding source; FIG. 2 is a sequence diagram showing the change in welding speed.

The method of ending the process of automatic welding with a melting electrode is carried out as follows.

At the moment when the welding electrode is located at a distance of 0.1 -1.0 of the nominal length of the weld pool to the end

cn (arivaed joint, the process is carried out in a pulse mode. In this case, the power of the welding source Pn in the pause is reduced to zero, the pause duration is maintained for 0.1–0.9 the duration of the weld pool crystallization. In the pulse, the power of the welding source Rn is increased up to the nominal, the duration of the impulse below: keep equal to the duration of the increase in the width and depth of the bath to their nominal values.

The change in the power of the welding source and welding speed is explained by the cyclograms presented in FIG. 12.

At time TI, the movement of the welding source of heat is stopped (welding speed | s becomes equal to zero), and its power Ri is reduced to zero. Moment p in-l; It starts with a pause. After the expiration of the first pause Tp, the welding process is resumed, increasing the power of the process to the nominal one and activating the mechanism for moving the source of welding heat (welding center) —the process is carried out in an impulse (mn is the arc re-initiation time), then | the moment ts the power of the welding source of heating is reduced to zero, the movement of the welding head is stopped, then the welding process is resumed again, while maintaining the nominal ratio of the feed rates of the electrode rod and the welding head. In the case of using strips, the described periodic welding process continues until d) complete crystallization of the living cross section of the weld, and then complete the process on the exit plate with the welding head stationary. If it is not possible to use lead bars (for example, when welding ring welds, welding with intersecting welds, etc.), the pulse process is continued to achieve the minimum possible length of the bath, and then finish the welding process with the fixed welding head, as in the case of using lead bars. Before the end of the welding process without lead bars, the metal bath is brought to the specified location (to the intersection with the adjacent plate when welding panels, to the beginning of the seam when welding cylindrical joints, etc.).

Due to the fact that at the end of the weld, the movement of the welding heat source is stopped, and the pulse melting of the electrode (electrode wire) continues, the crater is welded, filled with new portions of the electrode metal melted during the pulse. During the pauses, this metal crystallizes and in the subsequent impulse, surfacing occurs again. Due to this technique of welding termination, the formation of a crater at the end of the seam is eliminated, in its place a weld reinforcement is formed. Two to four periods of pulse and

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pauses enough to “heal the crater and melt the gain. A further increase in the number of periods of following pulses and pauses (more than four) is impractical because of the formation of an excessively high gain. A smaller number of the indicated periods (less than two) does not ensure that the crater is completely filled with liquid metal. Such an approach to the end of the welding process is particularly necessary in cases where it is not possible to use lead-outs (welding of circular seams, welding panels with intersecting seams, etc.). Reducing the feed rate of the melting electrode to 0.1 to 10 of its nominal value while simultaneously reducing the welding voltage 0.1-0.9 of the nominal voltage UB) saves electricity and reduces the height of the gain welded at the end of the weld - lugs The electrode melting during this period occurs due to the Joule heat generated at the point of contact of the electrode wire with the metal bath. When the melting electrode feed rate is less than 0.1 of its nominal value and the welding voltage is less than 0.1 UH, the electrode melting process slows down dramatically, the effect of feeding on crystallizing solidification disappears and this leads to the formation of a crater at the end of the seam. Increasing the electrode feed rate to more than 0.3 of its nominal value makes contact melting more difficult, and a short circuit and welding of the electrode to the product being welded occurs. When the welding voltage is more than 0.9 UH, an arc is excited, the contact melting of the electrode is stopped, which leads to an increase in the duration of the welding completion process. Example 1. Weld from Art. 3 GOST 380-74 size ZOOH 150X6. Samples were taken without cutting edges. The process was conducted under flux AN-348, wire Sv-08A with a diameter of 3 mm. A TS-17M welding tractor was used, powered by a VDU-1201 welding rectifier, to which a modulation unit was connected. On the remote control of the modulation unit, they were set to UHP, Uxxn, t, tab. Welding was performed in the mode: electrode wire feed speed, m / h; welding speed, 5 m / h; The no-load voltage and pause voltages were equal (, V, nominal power, 6 kVA, nominal weld pool length 40 mm. The crystallization time of the metal bath was found to be 4 s. At the time when the welding source was 40 mm away from the end of the welded joint, which corresponded to the nominal length of the weld pool, its movement was stopped, its power was reduced to zero.The duration of the pause was set to 0.1 duration of crystallization of the metal bath: t „0.1 tcr.

The duration of the re-excitation t = 0.2 s corresponded to the duration of the increase in the width and depth of the metal bath.

Example 2. Weldable and welding materials, equipment, as well as welding mode parameters Ve, VCB, t, etc., are the same as in Example 1.

After the welding source came to the end of the weld (the end of the weld), the movement of the welding source of heat was stopped and the process of melting the electrode (electrode wire) continued in a pulsed mode for three periods (three pulses and three pauses), which made it possible to melt the crater and weld the allowable force (6 mm).

Example 3. Weldable and welding materials, equipment and welding modes are the same as in the previous examples.

After the movement of the welding source of heat was stopped, the feed rate of the melting electrode was reduced to 0.2, 6 m / h, and the voltage between the melting electrode and the product was set to 0.5 V. This mode is the most optimal, since it allows saving electricity and reduce the height of the weld at the end of the weld gain to 4 mm. The electrode melting in this example is due to the Joule heat generated at the point of contact of the electrode wire with the metal bath.

The proposed method allows to solve the problem of high-quality weld end regardless of the presence of lead strips, which is especially important when welding "cards (panels) with intersecting seams and welding ring seams, allows you to completely eliminate shrinkage defects, and when high-speed arc welding saves a significant amount of metal on lead bars, which is especially effective when welding

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ke titanium and other expensive metals.

Claims (3)

1. The method of ending the process of automatic welding with a fusible electrode, in which the power of the welding source is programmed, characterized in that, in order to improve the formation of a seam at the end of welding, on the output strips at a time when the welding electrode is located at a distance of 0.1 - 1 nominal length of the welding bath to the end of the welded joint, the process is carried out in a pulsed mode, in which the power of the welding source in the pause is reduced to zero, the duration of the pause is 0.1-0.9 duration of the crystallization welding In a pulse, the power of the welding source is increased to a nominal one, the pulse duration is maintained equal to the magnitude of the increase in width and depth of the bath to their nominal values. 2. A method according to claim 1, characterized in that, in order to eliminate the crater during welding without lead bars, after the welding electrode movement has ceased, the electrode melting process is continued in a pulsed mode for 2-4 pulses. 3. Method according to paragraphs. 1 and 2, characterized in that, in order to save electricity and reduce weld reinforcement at the end of the weld without lead plates, after stopping the movement of the welding electrode, the electrode feed rate is reduced to 0.1-0.3 of its nominal value, and The distance between the electrode and the product is set to 0.1-0.9 of the rated voltage at a given feed rate of the electrode wire. Phie.1 & Ј, #. G / TgTzUIB tc FIG. 2