Pulse welding

Welding technology that uses high-current pulses to achieve material fusion.

Pulse welding uses high-current pulses to generate instantaneous, high-heat-energy pulses to achieve material joining. Its core process consists of three pulse stages: peak, mid-range, and base-range. In the peak stage, high-intensity currents (up to 500A) are applied for 0.5ms to 5ms to form a molten droplet in the welding wire. In the mid-range stage, wire retraction accelerations of up to 50m/min are used to control droplet shedding. In the base-range stage, wire feeding is achieved at 60m/min. This technology utilizes a dynamic parameter adjustment mechanism, combining Gaussian and rectangular pulses to control heat input distribution, addressing the problem of collapse in thin-plate aluminum alloy welding. By 2024, this technology will have developed a closed-loop system encompassing the welding power source, wire feed mechanism, and control system, enabling 0.1mm-level precision control in welding complex aerospace components.

Technical Principle

The welding power supply converts direct current into a high-frequency pulse current of 100-500Hz, generating temperatures of 3000-5000°C within 0.5-20ms. This causes partial melting of the material, followed by pressurized cooling to form a metallurgical bond. The core heat source is generated by anode heat (Qa = Ia²RaΔt) and cathode heat (Qk = Ik²RkΔt).

Process Control Stages

1.
During the pulse peak stage (t1), a high current of 500-800A is applied for a duration of 0.5-5ms. The welding wire is stationary or moving at a low speed (≤5m/min). The droplet diameter is controlled to an accuracy of ±0.05mm, and the contact tip temperature rise is limited to no more than 200°C.

2.
During the pulse mid-point phase (t2+t3), the wire is retracted at an acceleration of 20-50 m/s², reaching a maximum speed of 50 m/min. Precise fracture control is achieved by maintaining the droplet neck stress σ = εE (strain ε ≥ 0.15), with a fracture position deviation of < 0.1mm.
3.
During the pulse base-point phase (t4+t5), the wire feed acceleration is set at 30-60 m/s², with a peak speed of 50 m/min. Arc stability is maintained with a base current of 50-150 A, and the contact tip temperature drop rate is ≥ 100°C/s.