RU2179914C2 - Method for gas shielding of welding zone - Google Patents

Abstract

FIELD: gas shield welding by means of consumable electrode. SUBSTANCE: method comprises steps of supplying shield gas through shut-off device adjusted for necessary flowrate; determining shield gas flowrate according to welding parameters, namely: intensity of welding electric current, voltage of welding electric arc, welding speed and so on; closing shut-off device after termination of welding process. EFFECT: improved design allowing to significantly increase accuracy at controlling shield gas flowrate. 1 dwg, 1 ex

Description

 The invention relates to welding with a consumable electrode in a protective gas environment.

 A known method of gas protection of the welding zone, including opening before the start of the welding process of the locking device, purging the gas with a protective gas and supplying a certain amount of gas to the welding zone, followed by closing the locking device at the end of the welding process. (see Yu.G. Zaitsev. Diaphragm shutoff. Journal of Welding Production, 8, 1977, p. 49, Fig. 1, 2).

 The disadvantage of this method is the significant consumption of shielding gas, since its supply is regulated approximately and does not depend on the welding conditions, as a result of which there is poor protection of the weld pool, which affects the quality of the weld, then unjustifiably plentiful protection, which increases the consumption of shielding gas .

 The closest to the technical result is a method of gas protection of the welding zone, including opening the shut-off device before starting the welding process, pre-flushing the pipeline with shielding gas and supplying a certain amount of gas to the welding zone, followed by closing the shut-off device at the end of the welding process, the amount of shielding gas being determined according to the formula Q = kIU, where U is the welding voltage, I is the magnitude of the welding current, k is the gas flow coefficient (see the description of the patent of the Russian Federation 2009812, B 23 K 9/16, 03/30/1994).

 The described method is adopted as a prototype in the preparation of this application.

 However, the prototype does not provide accurate control of the shielding gas supply, since when calculating its value, factors such as the diameter of the electrode, metal thickness, welding speed and electrode stick-out, which significantly affect gas consumption, are not taken into account.

 The task is to increase the accuracy of shielding gas flow control.

где Q - расход защитного газа; I - сила сварочного тока; U - напряжение сварочной дуги; D - диаметр электрода; V - скорость сварки; S - толщина металла; L - вылет электрода.The problem is achieved in that in the method of gas protection of the welding zone, which includes determining the flow of shielding gas depending on the welding conditions and its supply through a shut-off device adjusted to a certain flow rate, followed by closing the shut-off device at the end of the welding process, the flow of protective gas is determined by the formula:

where Q is the flow rate of the protective gas; I is the strength of the welding current; U is the voltage of the welding arc; D is the diameter of the electrode; V is the welding speed; S is the thickness of the metal; L is the electrode overhang.

где Q - расход защитного газа, л/мин (литров в минуту); I - сила сварочного тока, А (ампер); U - напряжение сварочной дуги В (вольт); D - диаметр электрода, мм (миллиметр); V - скорость сварки, м/ч (метров в час); S - толщина металла, мм (миллиметр); L - вылет электрода, мм (миллиметр).The inventive method is characterized by the presence of a significant distinguishing feature, which allows to determine the flow of protective gas, presented in the form of a mathematical formula:

where Q is the flow of protective gas, l / min (liters per minute); I - welding current strength, A (amperes); U is the voltage of the welding arc V (volts); D is the diameter of the electrode, mm (millimeter); V - welding speed, m / h (meters per hour); S is the thickness of the metal, mm (millimeter); L is the extension of the electrode, mm (millimeter).

 Conducted research on patent - scientific and technical literature revealed a number of technical solutions for a similar purpose, however, they do not have a sign characterizing the claimed method. Therefore, there is reason to believe that the proposed method meets the eligibility criteria of the invention.

In the description accompanying the graph shown by the solid line the experimental Q _E and the dotted line the theoretical _T Q data flow of shielding gas.

 The gas protection method of the welding zone is as follows.

 Before starting welding, a locking device is opened for a few seconds to purge the gas supply in order to remove atmospheric air. The locking device can be performed in any design, equipped with a regulator of passage section, made, for example, on the basis of an electromagnet, the coil of which is fed by a welding current or in the form of a mechanical system.

открывают запорное устройство и производят процесс сварки.According to the welding conditions laid down in the technological process, taking into account the diameter of the electrode, welding speed, metal thickness and the magnitude of the electrode stick-out, the flow area of the shut-off device is adjusted using the formula:

open the locking device and produce the welding process.

 Example. Butt welding is performed on sheets of thickness S = 4 mm from St3 steel according to GOST 380-71 with an SV-08G2S electrode wire with a diameter of D = 1.2 mm according to GOST 2246-70 at a constant current of I = 200 A, welding arc voltage at reverse polarity U = 25 V, with a speed of V = 25 m / h when the electrode sticks out L = 12 mm. As a result, the shielding gas consumption calculated according to the above formula was Q = 10.3 l / min (liters per minute), with tabular recommended values of 8-12 l / min (see A. Potapyevsky. Welding in shielding gases with a consumable electrode M., "Mechanical Engineering", 1974, 240 pp.). The relative error in calculating the shielding gas flow rate from the recommended average value is 3% and is an example of 100% falling within the recommended value range.

Claims (1)

The method of gas protection of the welding zone, including determining the flow of shielding gas depending on the welding conditions and its supply through a shut-off device adjusted to a specific flow rate, followed by closing the shut-off device at the end of the welding process, characterized in that the flow of protective gas is determined by the formula:

where Q is the flow rate of the protective gas;
I is the strength of the welding current;
U is the voltage of the welding arc;
D is the diameter of the electrode;
V is the welding speed;
S is the thickness of the metal;
L is the electrode overhang.