Probeless Resistance Spot Welding Energy Control
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Solution Overview
Problem
Existing resistance spot welding systems face inefficiencies in achieving a high nugget diameter to energy ratio due to nonlinear and dynamic characteristics, and are prone to production delays due to broken probe wires used for voltage measurement.
Innovation Solution
A probeless energy delivery system that estimates resistance and adjusts voltage output based on a phase angle and power profile, eliminating the need for a feedback probe by using a power supply module, power delivery module, and voltage control module to manage electrical current and temperature effectively during the welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant voltage or constant current method is used, then the welding process is simple to control, but excess heat is supplied to the weld zone resulting in poor energy efficiency
Solution Approach 1:
The patent implements dynamic control of welding parameters by continuously adjusting voltage and current based on real-time resistance measurements from the probe wire. The system transitions from static constant voltage/current control to dynamic control where parameters vary throughout the welding cycle to match the nonlinear characteristics of the weld zone, optimizing energy delivery while preventing excess heat.
Solution Approach 2:
The system incorporates feedback control by measuring voltage across the electrodes through the probe wire and using this information to adjust the welding current in real-time. The controller monitors resistance changes and modifies power delivery accordingly, creating a closed-loop control system that prevents energy waste while maintaining precise control.
2Measurement precision
If probe wire is used to measure voltage and determine resistance, then real-time welding monitoring is achieved, but the probe wire often breaks causing production delays
Solution Approach 1:
The patent creates an electrical copy or model of the weld zone resistance by measuring voltage across the electrodes and calculating resistance based on current flow. This electrical measurement system replaces the need for physical probe wires that directly contact the weld zone, eliminating the mechanical wear and breakage issues while maintaining the ability to monitor welding parameters in real-time.
Solution Approach 2:
The system replaces the mechanical probe wire structure with an electrical field-based measurement approach. Instead of relying on a physical wire that must withstand mechanical stress and thermal conditions, the invention uses voltage and current measurements through the existing electrode circuitry to derive resistance information, substituting a fragile mechanical component with a robust electrical measurement system.
3Power
If constant heat method with linear power curve is used, then power delivery is predictable, but the system cannot be optimized for high nugget diameter to energy ratio due to nonlinear welding characteristics
Solution Approach 1:
The patent implements dynamic power delivery that adapts to the nonlinear resistance characteristics of the weld zone throughout the welding cycle. The system continuously adjusts voltage and current based on real-time resistance measurements, enabling the power delivery profile to match the actual thermal and electrical conditions in the weld zone, thereby optimizing energy efficiency and nugget formation.
Solution Approach 2:
The system dynamically changes electrical parameters (voltage, current, and their derivatives) throughout the welding cycle based on measured resistance values. By continuously adjusting these parameters in response to the nonlinear behavior of the weld zone, the system optimizes the nugget diameter to energy ratio, achieving better weld quality with less energy input compared to fixed linear power curves.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables efficient resistance spot welding without probes, optimizing energy delivery and reducing production downtime by maintaining consistent energy supply and adjusting for dynamic resistance without the need for probe wires.
Implementation Method 1
a power delivery module configured to receive the first electrical current from the power supply module and to generate a second electrical current from the first electrical current
Implementation Method 2
The first electrode and second electrode receive the second electrical current, which causes the resistance and temperature of the weld pieces to increase such that the weld pieces melt
Data Source
AI summary
A probeless energy delivery controller for a resistance spot welding system includes a power supply module that generates a first current and a power delivery module configured to generate a second current from the first current. The current is delivered to a first electrode and a second electrode that have at least two weld pieces interposed there-between. As the current flows through the weld pieces, the resistance and temperature of the weld pieces increase such that the weld pieces melt. The system further includes a voltage control module that receives a current reading indicating a value of the second current, estimates a resistance of the weld pieces based on the value of the second current, and determines a phase angle for setting a voltage outputted by the power supply module based on the estimated resistance and a power profile. The power supply module generates the first current based on the phase angle.