SU1288008A2 - Method of pulsed-arc welding with stepwise moved nonconsumable electrode - Google Patents

Abstract

The invention relates to gas-shielded arc welding, can be used in various areas of industry and construction when making butt joints with a non-penetrating electrode without filler wire, it is an improvement of the invention according to A. p. 889334. and improves the quality of the weld when welding materials with different thermal conductivities and different thicknesses. The electrode during the welding current pulse is given uniformly moving or alternating uniformly moving with uniform, and the electrode delay at the beginning of the pulse is set depending on the selected movement. The speed of the electrode during welding of materials with different thermal conductivities and different thicknesses can be chosen depending on the uniform speed of movement established during welding of the base material with melting temperature Td and thermal diffusivity df ,. The application of the method allows to improve the formation of the seam and to obtain the width of penetration with minimal deviations, 7, p. f-ly, 9 silt, 3 tab. € (L ND X) X) eo MS)

Description

The invention relates to gas-shielded arc welding and can be used in various areas of industry and construction in non-melted butt welding with an electrode without filler wire and is an improvement of the known invention in the author. St. No. 889334.

The aim of the invention is to improve the quality of the seam when welding materials with different thermal conductivities and different thicknesses, as well as improving the formation of the seam around the perimeter of the butt joint in different spatial positions,

Figures 1 through 6 show charts of welding current and speeds of movement of the electrode: with accelerated movement (Fig. 1); with a slow motion. movement (FIG. 2); with the alternation of accelerated, uniform and slow (Fig, 3); with alternation of slow, uniform and accelerated (Fig, 4); with the alternation of accelerated and uniform (Fig, 5); with alternation of slow and uniform (fig, 6) j in fig, 7-9 - charts of welding current, movement speed and movement step with regulation of heating time, movement speed and moment of switching off the welding current pulse (with changing movement step size for cases of uniform movement electrode and alternating uniformly moving with uniform.

The method is carried out in the following sequence.

Between the tungsten electrode and the product excite an electric arc. During a welding current pulse (1) after a preheating time (t under), previously selected by experiment or calculation, or controlled by an automatic device until the required initial penetration is obtained, the electrode is moved at a predetermined speed, determined by one experienced or calculated by, or speed set using an automatic device. When welding materials with different thermal conductivities of various thicknesses, the speed is prescribed according to Table 1, and is determined by the formulas or experience.

nym or specified by calculation. The movement of the electrode is carried out on the step size (S), limited by the adjustable off time

welding current pulse. The moment of switching off the welding current pulse is also chosen experimentally or by calculation, or it is controlled by an automatic device according to the specified penetration rate. At the end of the welding pulse current time (t (j), the welding current is reduced to the pause current value (), the crater is welded at a speed

equal to the speed of movement in the middle of the step, or at a uniformly variable speed with the continuation of the increase in shsh reduction after switching off the welding current pulse and turn off

moving the electrode. Crystallization of the weld pool occurs. The cycle is then repeated. In addition, in order to obtain a more reliable overlap of individual sections in addition to the cycle outlined below, during the pause (1), the electrode is moved in the direction opposite to the welding direction until the start of the next pulse,

Examples of the method are given in Table 2,

The delay of the electrode at the beginning of the pulse is set depending on the selected movement,

If the movement of the electrode begins with a gradual increase in speed, the delay of the electrode is set to such a duration that the penetration of the electrode is ensured.

the beginning of each section with a width of not more than half specified. In this case, at the beginning of the movement of the electrode with a slightly lower speed as compared with the previously accepted uniform penetration, it is quickly restored to a predetermined width and is further maintained by the selected - speed of movement.

If the displacement of the electrode begins with a gradual decrease in speed, the electrode delay is set to ensure penetration with a width close to the given one, since in this case, at the beginning of displacement with a slightly higher speed than previously accepted uniform, recovery of the penetration with a smaller value is difficult.

When moving the electrode at a uniform speed, the delay of the electrode is set to ensure penetration with a width that has an intermediate value among those received during accelerated and slow motion and is 50-80% of the target.

The accepted variations in the width of the penetration at the beginning of each section with any chosen pattern of electrode movement do not affect the width of the weld seam as a whole, since they are located at the overlap of two successive sections from which the seam is formed.

When welding butt joints in different spatial positions around the joint perimeter, the electrode moving step size during the welding current pulse by simultaneously adjusting the electrode delay at the beginning of the pulse, moving speed and switching off moment of the welding current, selected in accordance with the heat propagation pattern and spatial position of the electrode while ensuring the specified penetration within each separately welded section of the weld being formed. It is known that the amount of melting depends on the nature of heat propagation along the perimeter of the joint, as well as on the spatial position of the electrode during welding.

The delay of the electrode at the beginning of the pulse is adjusted depending on the provision of the dip with a width adopted in accordance with the selected movement. The speed of movement of the electrode by steps is smoothly controlled depending on the provision of the specified penetration during the period of movement of the electrode, each stage being interconnected with the duration of the delay of the electrode.

The moment of switching off the welding current pulse is controlled depending on the deviation of penetration from a predetermined value at the completion of the formation of each separately welded section.

All the listed parameters are set using automatic devices that work, for example, on

five

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0

five

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the principle of maintaining a constant temperature near the formation of the weld, as well as experimentally or by calculation, based on the known laws of thermal processes in welding.

In some cases, under the condition of ensuring stable melting, some of these parameters are regulated.

A change in the step size of the electrode during a welding current pulse allows programming the arc energy of the arc within the limits of each separately welded section around the perimeter of the joint in different spatial positions during welding of non-rotary joints of pipes.

Measurements of the penetration width of the completed welds are given in Table. 3

The use of this welding method allows to ensure high quality of welds from materials with different thermal conductivities and with a wall thickness of up to 6 mm without cutting edges, increasing productivity and reducing the amount of filler material required.

Claims (7)

1. A method of pulsed arc welding with a non-melting electrode with stepping movement along the ed. St. No. 889334, characterized in that, in order to improve the quality of welds when welding materials with different thermal conductivities and different thicknesses, the electrode is moved uniformly. 2. A method according to claim 1, characterized in that, when welding materials with low thermal conductivity, the electrode is moved equally accelerated, and the electrode delay at the beginning of the pulse is set to the time of formation of the weld at the beginning of each section with a width equal to no more than half of the specified value. 3. The method according to claim 1, which differs from: so that when welding materials with a higher thermal conductivity, the electrode is displaced equally-slowly, and the electrode delay at the beginning of the pulse is set at the time of formation of penetration at the beginning of each section with a width close to 3 adannah. five 4. The method according to claim 1, which differs from the fact that, when welding materials with low thermal conductivity, the electrode is displaced with alternating accelerated and uniform movements, and the electrode delay at the beginning of the pulse is set at the time of formation of the boil at the beginning of each section, equal to no more than half the given, 5. The method according to claim 1, characterized in that when welding materials with low thermal conductivity, the electrode is displaced with alternating slow and uniform movements, and the electrode delay at the beginning of the pulse is set at the time of formation of penetration at the beginning of each section with a width close to the specified one. 6. The method according to claim 1, characterized in that when welding materials with low thermal conductivity and a thickness of more than 4 mm, the electrode is displaced with alternation of slow, uniform and accelerated movements, and the delay is 88008 6 Yes, at the beginning of a pulse, it is set at the time of penetration at the beginning of each section with a width close to the specified one.  7. The method according to claim 1, which differs from the fact that when welding materials with a high thermal conductivity and a thickness of less than 3 mm, the electrode is moved with alternating usfO fundamental, uniform and slow movements, and the electrode delay at the beginning of the pulse is set to penetration time at the beginning of each section with a width not exceeding f5 is half given. 8, Method 1 pop, characterized in that, in order to improve the formation of the seam when conducting the process in different spatial positions, the magnitude of the electrode moving distance is changed simultaneously by adjusting the electrode delay time at the beginning of the impulse, its moving speed and the moment of switching off the impulse. welding, current. Current barometric diagram Zi inod . Travel speed chart Cdapot mao tone chart Uh uh inep .. Phage2 current assembly current cSapovHoso current chart Fig J; U; S yield current 5 J; UiS n Daagranma assembly current :; U; S 1288008 Diagram of the assembly current uztn iu3. Chz Ut Ui Travel speed chart -per.1 per-}. Movement Step Chart tnep.s 3 S {H / CSapdwoeo diagram (for now taztn tu3 Uxt 4i UH / Hz tnep-i Travel speed chart y / rj from - II g Uhs tnep.2. tnep-3 Movement Step Chart % S / S2 tui The diagram is both straight about current tuz, / 7. iu3. and P Diagram of movement speed Us X W2  P Us UKZ ikz one  lane 1 Chart step skew, eni nep-i inep.3 S / S2 Fie.9