Electronic pulse spot welding machines achieve precise control of welding time through sophisticated circuit design and advanced control algorithms. This process spans key stages such as pre-compression, energization, and cooling. Its core lies in decomposing the welding cycle into multiple independently adjustable time parameters and ensuring the execution accuracy of each stage through a closed-loop feedback mechanism, thereby meeting the stringent welding quality requirements of different materials and processes.
The pre-compression stage is the starting point of the welding process. When the electrode begins to contact the workpiece, the pre-compression time determines the time required for the electrode pressure to reach a stable state from its initial value. This stage must ensure full contact with the workpiece surface, eliminating gaps and air, and creating stable conditions for subsequent energization welding. Insufficient pre-compression time leads to poor workpiece contact, resulting in excessive local resistance, causing spatter or incomplete welds; excessive pre-compression time may affect the weld morphology due to over-compression of the material. Electronic pulse spot welding machines achieve precise setting of the pre-compression time through mechanical or pneumatic adjustment devices combined with pressure sensor feedback, typically within the range of 0.1 to 0.3 seconds to accommodate workpieces of different thicknesses and materials.
The energization stage is the core of welding quality. Electronic pulse spot welding machines employ pulsed current technology, breaking down a single welding cycle into multiple short pulses. The duration (pulse width) and interval (pulse interval) of each pulse are independently adjustable. For example, when welding thin plates, shortening the pulse width and increasing the pulse frequency reduces the total heat input, preventing burn-through. Conversely, when welding thick plates, extending the pulse width and reducing the frequency ensures sufficient heat penetration into the material. This "high-frequency spot welding" energy output method upgrades welding time control from traditional continuous adjustment to discrete, programmable, and precise control.
The cooling phase directly affects weld performance. After power is cut off, the weld nugget needs a certain cooling time to solidify. Insufficient cooling time leads to coarse weld grains and decreased mechanical properties; excessive cooling time may cause workpiece deformation or stress concentration. Electronic pulse spot welding machines dynamically monitor the weld nugget cooling process using built-in timers and temperature sensors, automatically adjusting the cooling time accordingly. For example, when welding materials with high thermal conductivity (such as copper and aluminum), the system extends the cooling time to compensate for rapid heat loss; while when welding materials with low thermal conductivity (such as stainless steel), the cooling time is shortened to improve production efficiency.
Dual-pulse and multi-pulse processes further expand the dimensions of time control. Dual-pulse spot welding adds a tempering pulse after the main welding pulse. By precisely controlling the interval between the two pulses, the weld joint is reheated after cooling below the martensitic transformation point, achieving ductile fracture.
Multi-pulse processes optimize the microstructure distribution of the weld joint by superimposing multiple tempering pulses, significantly improving fatigue performance. These processes require extremely high precision in time parameters; the interval error must be controlled within milliseconds, otherwise, the weld joint performance will be unstable.
A closed-loop feedback mechanism ensures the accuracy of time control. The electronic pulse spot welding machine uses current sensors, voltage sensors, and displacement sensors to monitor key parameters in the welding process in real time and feeds the data back to the control unit. When a deviation between the actual welding time and the set value is detected, the system immediately adjusts the pulse width, frequency, or electrode pressure to compensate for interference factors (such as power grid fluctuations and changes in the oxide layer thickness on the workpiece surface). This dynamic correction capability ensures that welding time control remains highly accurate in actual production.
The electronic pulse spot welding machine, through the time segmentation of the pre-pressure, power-on, and cooling stages, combined with pulse technology, multi-pulse processes, and a closed-loop feedback mechanism, constructs a multi-level, high-precision welding time control system. This system not only improves the consistency and reliability of weld quality but also provides technical support for high-end applications such as dissimilar material welding and precision micro-connection, becoming an indispensable core piece of equipment in modern manufacturing.
