Control circuit for arc characteristics of pulse type gas shield welding

Abstract

Provided is a control circuit for arc characteristics of pulse type gas shield welding. A fixed contact of a potentiometer is sequentially connected with an emitting electrode of a first resistor and an emitting electrode of an optical coupler. A movable contact of the potentiometer is connected with a collecting electrode of the optical coupler. An emitting electrode of the optical coupler is connected with a positive electrode of a detector diode, and a collecting electrode of the optical coupler is connected with a negative electrode of the detector diode. The input signal end of the optical coupler is connected with an output diverter of an electric welding machine. The collecting electrode of the optical coupler is connected with the non-inverting input end of an operational amplifier, one end of a second resistor, one end of a capacitor and the positive electrode of the diode. The other end of the second resistor, the other end of the capacitor and the negative electrode of the diode share the identical grounding end. The collecting electrode of the optical coupler, a third resistor and the inverted input end of the operational amplifier are connected in sequence. The output end and the operational amplifier end of the operational amplifier are connected so that a follower circuit can be formed. The output end of the operational amplifier is further connected with a current adjustment error signal. The control circuit can maintain the stability of the arc characteristics.

Description

Technical field: [0001] The invention relates to the technical field of electrical control of pulsed MIG welding arcs, in particular to a control circuit for characteristics of pulsed gas-shielded welding arcs. Background technique: [0002] The pulse MIG welding method is also called pulse MIG shielded welding. The melting electrode is a welding wire, and the main body of the shielding gas is an inert gas, which accounts for more than 80% of the total shielding gas flow. The welding current of pulsed MIG welding adopts pulsed current waveform, the purpose of which is to obtain a superior droplet jet transfer mode at a lower average current. When the welding droplet is in the jet transition mode, the arc is very stable, there is no welding spatter, the arc heat input and penetration are strong, the weld shape is very good, and the weld quality is high. DC MIG welding must be above the critical current value of the welding wire to obtain the jet transition mode. The peak cur...

AI Technical Summary

Problems solved by technology

[0004] In order to take care of the stability of the arc during arc maintenance, the external characteristics of the constant current power supply are selected during the arc maintenance period; due to the use of constant current characteristics, the arc maintenance current remains unchanged when the arc length changes due to disturbances, so that the pulsed MIG welding arc is stable during the arc maintenance period. The self-adjusting performance of the arc length is lost; although the constant voltage external characteristic is used during the pulse period, in order to ensure a stable droplet jet transition mode, the pulse current change should not be too large

Therefore, for the traditional pulsed MIG welding arc, there is no self-regulation performance during the arc maintenance period, the self-regulation performance during the pulse period is very limited, the self-regulation performance of the entire arc is very poor, and the stability and adaptability of the arc length are poor when disturbances occur

Because the traditional pulse MIG welding arc control system has the defect of poor arc length self-adjustment performance in principle, it has the following serious problems in its application:

Since the arc length self-adjustment performance of the arc is very poor, the setting of the above parameters must be very precise, so that the melting speed of the welding wire generated by the arc under the set parameters is exactly equal to the set wire feeding speed, otherwise the arc length will deviate greatly from the normal range, even Can't get normal arc

Moreover, in addition to obtaining the normal arc length, it is also necessary to obtain the jet transition mode of the droplet, which greatly increases the difficulty of parameter setting and system use.

[0007] Second, the arc self-adjustment performance is poor, and the arc length stability and adaptability are poor when the arc length is disturbed;

[0008] When the arc length is disturbed, the change of the current and the melting speed of the welding wire is very small, the recovery ability of the arc length is very poor, and the arc length stability and adaptability of the arc are very poor.

[0009] Third, the droplet transfer stability is poor

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