RU2113329C1 - Method of control of length of a c arc by value of voltage in it while consumable electrode is used for welding - Google Patents

Abstract

FIELD: electric arc welding. SUBSTANCE: invention refers to automatic control of process of electric arc welding. Voltage of initial firing of arc that is measured in it in zone of transition of its current through zero value is employed as feedback signal over length of arc. EFFECT: increased quality of weld thanks to enhanced precision of maintenance of length of arc. 2 dwg

Description

 The invention relates to welding production, namely to automatic regulation and control of welding processes by alternating current.

 Known methods for controlling the length of the arc, based on the measurement of its intensity in a certain frequency spectrum, but, firstly, they require the installation of special sensors in the zone of extreme operating conditions and, secondly, they are not always applicable, for example, when welding under submerged arc [ one].

 There are also known methods of regulating the length of the arc by the magnitude of the voltage on it when welding with a consumable electrode by changing the feed speed of the electrode wire according to the error signal between the actual voltage on the arc and its set value [2].

 However, in the general case, and especially at small and high current densities (or at small and high gas ionization in the arc column), the voltage on the arc depends not only on its length, but also on the current [1 p. 39]. This dependence does not allow to unambiguously monitor and maintain its specified length with a changing arc current, which, of course, leads to a deterioration in the quality of the weld — a change in its geometry. The influence of the variable current component on the arc voltage makes it possible to evaluate the oscillograms shown in FIG. 1 (a, b) - this component is equal to 40 or more percent of the arc voltage.

 An object of the invention is to improve the quality of the weld by increasing the accuracy of regulating the length of the arc.

 The problem is achieved in that in the method of controlling the length of the AC arc by the voltage on it when welding with a consumable electrode by changing the feed speed of the electrode wire, the initial ignition voltage of the arc, which is measured on the arc in the transition zone of the arc, is used as a feedback signal current through zero value.

 In the known method, the feedback signal along the length of the arc, its voltage contains a varying component, depending on the arc current and its dynamic resistance, which are not taken into account in it, which does not allow it to be accurately supported. Measuring the arc voltage at currents of hundreds and thousands of times less than workers makes it possible to obtain reliable information about the length of the arc and maintain it equal to a given value.

 Significant features that are distinctive from the prototype, namely, the use of the voltage of its initial ignition as the arc length information, which is measured on an arc in the zone where its current passes through a zero value, allows us to consider the proposed technical solution as meeting the criterion of "significant differences".

 In the study of the proposed solution in the patent and scientific literature, technical solutions were not identified that contain features that distinguish the claimed solution from the prototype and, therefore, this technical solution meets the criterion of "novelty."

 In FIG. 2 shows a structural diagram for implementing the inventive method, comprising an arc current sensor 1, a comparator of this current 2, which is connected by its output to the interrupt input of the microcontroller 3; arc voltage sensor 4, the signal from which is fed to the ADC of the microcontroller; welding wire feed drive 5, receiving a signal for setting the feed rate from the DAC of the microcontroller, which is generated by the program regulator of the arc length.

 The method is implemented as follows.

 When the arc current passes through zero at time t1, the comparator 2 and its output signal, shown in FIG. 1 V, is fed to the interrupt input of the microcontroller 3, which interrupts the current program for measuring the voltage on the arc given to the input of its analog-to-digital converter. After the measurement is completed, the arc length regulator subroutine comes into operation, in which the mismatch signal between the set and the actual value of the initial ignition voltage of the arc is calculated and the signal value is adjusted at the feed rate of the welding wire taken from the output of the digital-to-analog converter of microcontroller 3 and supplied to drive 5 .

 With this method of regulation, the accuracy of maintaining the length of the arc can be increased tens of times, which will improve the quality of the weld.

 Literature.

 1. Petinov OV, Medvedev V.A. A method of automatically controlling the length of the arc during electrode welding and cutting. Auth. St. N 1074673, CL B 23 K 9/10. Declared on 01.29.82. Published. 02/23/84., Bulletin No. 7.

2. Shakhnov A. D., Osipov G. G., Kuznetsov A. P. The method of regulating the length of the arc when welding with a consumable electrode. Auth. St. N 766781, CL B 23 K 9/10. Declared 05/27/77. Publ. 09/30/80, Bulletin No. 3. /
3. Theory of welding processes. /Under. ed. V.V. Fedorova - M.: Higher School, 1988, p. 559.

Claims (1)

 A method of regulating the length of an AC arc by the magnitude of the voltage on it when welding with a consumable electrode by changing the feed speed of the electrode wire, characterized in that they use the initial ignition voltage of the arc, which is measured on the arc in the zone where its current passes through a zero value.

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