SU1698004A1 - Method of arc facing in shielding gas medium - Google Patents

Abstract

The invention relates to electric welding and can be used in the elimination of operational defects of monoblocks of internal combustion engines of diesel engines mainly from aluminum alloys. The aim of the invention is to simplify the process by eliminating the preheating operation and subsequent slow-down cooling of the monoblock. The invention relates to electric welding and can be used to eliminate the operational defects of mono-blocks, mainly aluminum alloys, internal combustion engines. The aim of the invention is to simplify the process by eliminating the preheating operations and subsequent slow-down cooling of the monoblock, increasing the strength and density of the welds, increasing the strength and density of the welded joints, and reducing the heat in the monoblock. Welding of the operational defect in the monoblock is carried out by shielding gas welding with a pulsed feed of the welding electrode. The ripple frequency when the electrode is applied is determined from the ratio f mlcu / d, where f is the pulse frequency of the electrode, Hz, St is the welding current, d is the diameter of the electrode wire, mm, 28; 1.0 In case of welding of internal defects of the monoblock, the flow rate of protective gas supplied to the arc burning zone is determined from the ratio Q 15 xT0d & -exp (-0.04Т0), where Q is the protective gas consumption, l / min, Then is the current welding time, s, do is the diameter of the mounting slot in the monoblock under the cylinder sleeve, m. The choice of the pulse frequency of the electrode and the protective gas consumption these ratios can reduce the heating of the weld zone, the likelihood of formation of crystallization cracks and pores in the monoblock, reduce the consumption of expensive protective gas while maintaining the quality of the welding point. 1 tab., 1 Il. compounds, as well as a decrease in heat transfer to a monoblock. The drawing shows a graph of the dependence of the flow of protective gas when welding the internal defect of the monoblock from the current welding time. The method is carried out as follows. Monoblock diesel-insulated internal combustion engine made of aluminum alloy, cleaned of contamination, having internal and external combustion engines С о о 00 о о 4

Description

These defects are subjected to repair welding of defects by welding in a protective gas (for example, argon) with a pulsating supply of a melting electrode. To do this, the welding torch is installed above the defect, welding current and voltage is applied to the electrode, the protective gas is turned on and the monoblock is filled with the molten metal of the electrode defect, while the electrode is supplied with a pulsation frequency determined from the formula

f (0.28 ... 1.0) -C-, "d3

where f is the pulse frequency of the electrode, Hz;

ICB - welding current, A;

d is the diameter of the electrode wire, mm.

In the case of welding of internal defects of the monoblock, the flow rate of protective gas supplied to the arc burning zone is determined from the formula

 Tg ° exp (-0.04Т0), where Q is the protective gas consumption, l / min;

That is the current welding time, s;

do is the diameter of the seat in the monoblock under the cylinder sleeve, m.

When the defect is filled with the molten metal of the electrode, the welding process of the defect is stopped.

The frequency of the pulsations of the electrode determines, first of all, the size of the droplets on the end of the melting electrode, the duration and frequency of their transition through the arc gap. If you choose a frequency with coefficients in the formula less than 0.28, this will cause an excessive increase in the diameter of the droplets, their overheating, an increase in the proportion of heat transferred to the bath by drops, an increase in splashing, a deterioration in the formation of weld metal, an increase in heat input to the base metal (monoblock). As a result, the level of residual welding stresses increases, the likelihood of cracks in the welded joint increases, and the strength and density of the weld metal decreases.

With an increase in the frequency of pulsations of the electrode wire above the limits established in the formula, the welding process becomes similar to the process of pulse-arc welding, the main purpose of which is to control the drop-transfer and reduce welding spray, but not to control the crystallization processes in the weld pool. That is why the appointment of the frequency of pulsations with a factor of more than 1.0 leads to a decrease in

the effectiveness of the process on the degassing of the weld pool metal and the grinding of the structure of the welds, which is explained by a decrease in the vibration of the weld pool.

A change in the flow rate of shielding gas in the process of welding an internal defect according to a given dependence ensures a decrease in heat input during the welding process and

reduces gas consumption for the welding process, since the amount of gas supplied to the welding zone corresponds to the necessary need to protect the welding zone, which drops when the monoblock is filled with protective gas.

Example. Cracks were made in the valve jumpers of used monoblocks for M400 marine diesel engines made of AL 4 alloy.

Welding was performed with a pulsed electrode feed with a change in the coefficient in the formula to determine the pulsation frequency and a change in the coefficients in the formula to determine the flow of protective gas. The results of the welding process are listed in the table.

The use of the proposed method of welding defects in monoblocks of internal combustion engines allows to increase

the productivity of the welding process, reduce energy consumption for its implementation, increase the strength of monoblocks and their service life.

F o rumlula and z o breetn

. The method of arc surfacing in a protective gas environment, in which the deposition is carried out with a melting electrode, characterized in that, in order to improve the quality and simplify the method by eliminating the heating and cooling operations during the repair of monoblocks of internal combustion engines, the welding is carried out with a pulsating electrode feed, the frequency of the pulsations is chosen from the ratio

45

f m - g

where ICB is the welding current;

f is the frequency of pulsations, Hz;

d is the diameter of the electrode wire, mm, t $ 0.28; 1.0,

and the flow of protective gas when welding internal cavities is chosen according to the formula

Q 15T0loexp (-0.04To), where Q is the protective gas consumption, l / min;

That is the current welding time, s; d0 is the diameter of the seat in the monoblock under the cylinder sleeve, m.

Note: In all cases, the grade of welding wire - Sv AK5 / GOST 7871-75 /, Z.Dl for tensile strength in the numerator shows the minimum and maximum values, in the denominator - the average of three - five definitions .5. The main time T0, which depends on the depth of the defect and the shape of the welding seam, varies from 30 to 120 seconds,

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Claims (1)

Claim The method of arc surfacing in a protective gas environment, in which the surfacing is carried out with a consumable electrode, characterized in that, in order to improve the quality and simplify the method by eliminating heating and cooling operations when repairing monoblocks of internal combustion engines, surfacing is carried out with a pulsating electrode supply, the pulsation frequency is selected from the relation f _t ! svt - hl -> d ³ where 1sv is the welding current; f- ripple frequency, Hz; d is the diameter of the electrode wire, mm, t ^ 0.28; 1,0], and the flow rate of the protective gas when welding the internal cavities is selected by the formula Q = 15 T0 ⁰ exp (-0.04To), where Q is the flow of protective gas, l / min; That is the current welding time, s; do - the diameter of the seat in the monoblock under the cylinder bushing, m Diameter of an electrode, mm Current, A Voltage Pulse frequency, Hz Nature of the process The presence of cracks, pores The tensile strength of the weld metal, MPa Note 1,6 220 25 49 Sta- Defek 180-240 The polarity is spatter, no spray you are absent 210 military 1,6 220 28 16. Also Also 140-280 190 n 2.0 260 22 thirty n 150-260 205 2.0 260 24 10 _ and 190-250 220 2.0 260 24 fifteen 170-250 210 Note: In all cases, the brand of welding wire is Sv AK5 / GOST 7871-75 /. Z. For ultimate strength, the numerator shows the minimum and maximum values, and the denominator shows the average of three to five definitions. 5. The main time T _o , depending on the depth of the defect and the shape of the groove for welding, varies within 30 - 120 s.