Weld Head Clamping Force Control via Motor Current Adjustment
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Solution Overview
Problem
Conventional weld heads face challenges such as cumbersome electrode replacement, misalignment issues, susceptibility to temperature variations affecting clamping force, and electrode damage due to magnetic strength variations and power cutoff.
Innovation Solution
A weld head with a permanent-magnet linear actuator motor, temperature sensor, and controller to adjust current, a brake assembly to prevent electrode collision, and adaptable electrode assemblies for various configurations, addressing temperature and magnetic strength fluctuations and ensuring consistent clamping force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional weld heads use a linear actuator motor to adjust electrode position, then electrode positioning is achieved, but clamping force varies due to magnetic strength variations along the motor stroke
Solution Approach 1:
A force sensor is integrated into the weld head to detect the actual clamping force applied by the electrodes. The controller receives this force signal and adjusts the linear actuator motor's operation in real-time to maintain a predetermined clamping force, compensating for magnetic strength variations along the motor stroke.
Solution Approach 2:
The system dynamically changes the electrical parameters (current/voltage) supplied to the linear actuator motor based on the detected clamping force. By adjusting these parameters in response to force sensor feedback, the system maintains consistent clamping force despite positional variations in the motor's magnetic field.
2Adaptability or versatility
If conventional weld heads allow electrode replacement, then different electrode configurations can be used, but replacement is cumbersome and time-consuming
Solution Approach 1:
The weld head is divided into modular components, with the electrode assembly being a separate, easily detachable unit. This segmentation allows the electrode to be quickly removed and replaced without affecting other parts of the weld head, significantly reducing replacement time while maintaining versatility.
Solution Approach 2:
The weld head incorporates a universal mounting interface that can accommodate different electrode types and configurations. This standardized interface allows various electrodes to be quickly swapped while maintaining proper alignment and electrical connection, enhancing adaptability without requiring complex reconfiguration.
3Device complexity
If conventional weld heads operate without temperature compensation, then the structure is simpler, but temperature variations adversely affect force output and weld quality
Solution Approach 1:
A temperature sensor continuously monitors the temperature of the linear actuator motor and provides this information to the controller. The controller uses this temperature feedback to adjust operational parameters, compensating for thermal effects on magnetic strength and maintaining consistent clamping force and weld quality.
Solution Approach 2:
The system dynamically adjusts electrical parameters supplied to the linear actuator motor based on temperature readings. By changing these parameters in response to temperature variations, the system compensates for thermal degradation of magnetic performance while adding only minimal control complexity.
4Loss of energy
If power is cutoff from conventional weld heads, then energy consumption is reduced, but electrodes strike each other causing damage and premature wear
Solution Approach 1:
A brake assembly is incorporated into the weld head that is automatically activated when power is cutoff. This brake prevents the electrode from falling and striking the workpiece or opposing electrode, protecting the electrodes from damage. The brake is designed to engage automatically upon power loss, requiring no additional energy consumption.
Solution Approach 2:
The brake assembly provides a preliminary counter-action to the gravitational force that would cause the electrode to fall when power is cutoff. By engaging the brake before electrode damage can occur, the system prevents the harmful effect without requiring continuous energy input.
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
Enhances the efficiency and quality of spot welding by maintaining consistent clamping force, preventing electrode damage, and simplifying electrode replacement and alignment.
Implementation Method 1
A weld head with a permanent-magnet linear actuator motor
Implementation Method 2
temperature sensor, and controller to adjust current
Implementation Method 3
a brake assembly to prevent electrode collision
Implementation Method 4
As current is passed through the electrodes, the electrical resistance supplied by the components tends to locally heat the components around the points of contact of the electrodes
Data Source
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AI summary
A weld head for spot welding two or more components together. The weld head includes first and second electrode assemblies and a linear actuator motor to drive the first electrode assembly into a desired position and apply a desired clamping force. The weld head may include a sensor configured to measure a temperature of the motor and a controller configured to monitor the temperature and adjust the current supplied to the motor to maintain the desired clamping force. The weld head may include linear encoder to measure the position of the linear actuator motor and an algorithm that correlates the position of the motor with a force constant of the motor. Based on the position of the motor and the corresponding force constant of the motor, the controller is configured to adjust the current supplied to the motor to maintain the desired clamping force.