SU1346369A1 - Method of automatic control of fusion depth in welding with nonconsumable electrode - Google Patents

Abstract

The invention relates to the welding of long joints with a predetermined penetration depth. The aim of the invention is to improve the quality of the weld by maintaining a predetermined penetration depth along the entire length of the weld, regardless of the change in welding conditions: thermal efficiency, degree. The invention relates to welding production and can be used in the production of electric welding, rub. The aim of the invention is to improve the quality of the weld by compensating for the process of welding uncontrolled disturbances of various physical nature, such as changing the thermal efficiency, changing the degree of distribution of the welding heat source, changing the coefficients of the earth heat capacity and thermal diffusivity of the energy source, volumetric heat capacity and thermal diffusivity. The actual penetration depth is monitored only on the outside of the weld. For its evaluation, a controlled section is selected at a certain distance behind the welding torch. The width of zone B, heated above a given temperature T, i.e. the isotherm width at T, and the surface temperature T, in the dentra of this section. To assess the current welding conditions, a criterion parameter K Vu / 1n (T, yT3) was proposed. A calculation formula for the required width of the isotherm B corresponding to Tj for a specific criterion parameter was proposed. The constant penetration depth is maintained by influencing the welding current taking into account the difference (Bf-Bp). 2 Il. material that influences the change in the depth of penetration both upwards and downwards, using the means of controlling only the outer side of the weld. Two parameters of the temperature field of the surface of the schv are used: the width of the isotherm of a given temperature and the temperature in the dent of the controlled cross section, with the help of which 3 the effect on the welding process of uncontrolled disturbances of a special type. 5S W with O5 with Oi with

Description

For the implementation of the method, a section of the weld that is free for access by the measuring means and located at a distance X from the axis of the welding tool is preselected. The temperature of the controlled isotherm Tj is determined, which is determined by the distance X and the adjustment of the measuring means of the isotherm width.

Initially, in normal operation, the nominal values of the welding current I, of the welding speed V, the arc voltage U, determining the nominal value of heat input energy, are measured. At the same time, the nominal value of B is measured, the width of the section of metal heated above a given

temperatures d

Tj and the selected cross-section of welded pgea, as well as the temperature T, in the center of this area. From these two values, the nominal value of the criterial parameter is calculated in accordance with the expression obtained from the equation relating to the process of heat distribution from the distributed source in a flat layer. The term criterion parameter is understood as the degree of influence of uncontrolled disturbances.

to the depth of penetration. I

At constant welding speed

the deviation of the criterial parameter from the nominal value indicates the presence of perturbing factors of a special type; under the action of KOTopbix, the seam shape changes. In this case, the specified penetration value corresponds to a certain shape of the temperature field on the surface of the product, the controlled parameter of which is the width of the layer heated above the specified temperature, i.e. isotherm width of a given temperature In this case, in order to maintain the desired penetration depth, it is necessary to change the welding mode so that the isotherm width takes the calculated value BP, which is uniquely related to the welding speed / IV deviation and the criterion parameter deviation l K. As the criterion parameter K depends on the welding speed , introduces the correction term m 3 and S.

The values of the empirical coefficients tn ,, n, P1 are determined by preliminary experiment. During normal operation, increase

d

five

0

five

0

five

0

five

0

five

welding speed by the value of l and fix the change in the width of the controlled isotherm lV and the deviation of the criterion parameter lK. In this case, m, /) Bi / m3 dKi / dS. By returning the process to its original state, the degree of distribution of the heat source is changed by increasing the arc length. The deviation of the criterion parameter LK is determined. The welding current is increased so as to achieve the required penetration, the width of the controlled isotherm reaches the value of B. At the same time, m (Bj-Bj,) / 4K, j. Subsequently, during the welding process, the deviation of the set mode parameters and Bp from Bj is measured continuously and, in order to maintain the set penetration depth, the welding current is changed in accordance with the expression

dI (l, dV-l, j) U-lj (By-B),,, l Io / Vo, l4 Io / Uo.

The first two members of the right side of the outflow set the control loops on the directly measured disturbances and reflect the process of stabilization of the current value of heat input, the required value of which is determined by the third member, which sets the negative reversible relationship across the width of the isotherm being monitored.

The factor 1 is determined from the considerations of ensuring the sustainability and quality requirements of the automatic welding current control system.

FIG. 1 shows a scheme for measuring the parameters of the surface temperature field) in FIG. 2 is a diagram of a device implementing the proposed method.

When the welding torch moves along axis 1 at a distance X from the torch, a controlled section 2 is selected. Position 3 shows the isotherm bounding the melt zone, position 4 the isotherm corresponding to the given temperature.

A welded 1 € 5 nt is set in motion by the forming rolls 6 at a speed S. The welding arc 7 is energized in the burner 8 fed from a controlled welding spot.

s

9, melts the edges of the billet 10, forming a weld 11. The welding process is monitored by speed sensors 12 and voltage 13, welding current 14, by a television sensor 15 measuring the width of a section of material heated above a predetermined temperature, parameter 16. Device data 12-16 are fed to the computing device 17, where the magnitude of the control action of the welding current is determined in accordance with the specified expressions with regard to the constants that are stored in the memory unit 18.

If during welding, due to the influence of external factors, a change in the depth of penetration occurs, then a control action is supplied to the power source 9 and changes the welding current in such a way as to restore the required amount of penetration.

The method of automatic adjustment of the depth of penetration in automatic argon-arc welding by non-standard shchimi electrode is implemented in the automated control system for welding pipes of steel 12X18H10T with a diameter of 38 mm and a wall thickness of 2 mm in the ADS 10-60 mill. Blocks 17 and 18 (Fig. 2) are made on the basis of a microcomputer Electronics DZ-28 with UDR ATSSKS-1024-001. A speed sensor BE51B, a television sensor based on a small-sized television installation MTU-1, equipped with a measuring unit for measuring the size of a bright object FROM 131.02, a partial emission sensor ПЧД 131 with a secondary measuring transducer ПВ-3 are used.

Welding is carried out at a nominal speed of 4 m / min, current 600 A, voltage 20 V. Empirical coefficients take the values m, 1.2 mm / m / min} t 1.9 MM / CM i 0.13 cm / M / MHHj 1,150 A / M / MHHj A / Bj 1.97 A / mm.

The system ensures uninterrupted operation of welding equipment for hours and then replacing the electrode. During this time, the value of the criterion parameter varies between 3.2-4.8 cm. The welding current changes to 85 A. As a result of the system’s operation for four hours, it is possible to lower the reversing bead size by 2.86 times.

for and the standard deviation of the back roller 1.83 times. I

The use of the method provides compensation for the effects on the process of measured and uncontrolled technological disturbances, which allows, without loss of quality, to increase the welding speed by 100%. At the same time, the working conditions of the welder-operator are improved, the requirements for his qualification are reduced.

Claims (1)

Invention Formula The method of automatic adjustment of the penetration depth during welding with a non-consumable electrode, at which the nominal values of welding current, welding speeds and arc voltage are set, the current values of these parameters are measured during the welding process, as well as a given point on the surface of the product, characterizing the effect of uncontrolled disturbances during welding, and the information obtained is used to maintain a given depth by adjusting the welding current in accordance with the deviations of the measured parameters from those given with uncontrolled disturbances, characterized in that, in order to improve the quality of the weld by compensating for the effect on the penetration depth of uncontrolled disturbances of various physical nature, behind welding arc, at a distance from it, a controlled cross section of the weld is pre-selected and temperature measurement of the surface on the center of this section is carried out, the temperature is additionally set lower than in the center and in the specified section the width of the zone heated is specified in this section temperatures as well when adjusting the welding current to account for uncontrolled disturbances use the expression 1 (В „-Вр), where 1 is the coefficient chosen from the condition of ensuring the stability requirements of the automatic control system;  current width of the measured area; BP-design width specified the zone corresponding to the required penetration depth under specific welding conditions, while RR p, l5 + P2 (| K + PzL5), JK K - K ,, K, (), de Bp - measured width of the specified zone with nominal parameters of the mode} Cd is a criterion parameter characterizing specific welding conditions and calculated using the last formula with nominal mode parameters} K - same with current welding parameters j TC - measured temperature; Tj. - set temperature j 4S - increment of welding speed,, п ,,, n - empirical coefficients, previously determined by experiment. Ifutt Editor I. Shulla Compiled by E. Somov Tehred L. Serdyukova CorrectorM. Maksimishinets Order 3564 Circulation 894 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 4/5, Moscow, Zh-35, Raushsk nab. 113/35 Production and Publishing Combine Patent, Uzhgorod, st. Gagarin, 101 Subscription