Spot Welding Gun Calibration Using Two Pressure Reference Points
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Solution Overview
Problem
The relationship between welding pressure and torque in spot welding guns can change due to factors like servo motor deterioration and electrode tip wear, necessitating frequent calibration to maintain welding accuracy, especially when working with varying workpiece thickness and material.
Innovation Solution
A welding apparatus that includes a servo motor-driven spot welding gun with a control device capable of calibrating the welding pressure/torque relationship by prompting user input for multiple pressures, identifying movement amounts, deriving a relational expression between pressure and movement, and estimating required torques for different pressures, allowing for automatic calibration of the welding pressure/torque relationship.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the welding pressure/torque relationship is calibrated for each pressure point manually, then the welding accuracy is maintained, but the calibration time and effort increase significantly
Solution Approach 1:
The system performs preliminary calibration at only two reference pressure points, storing the torque values. When calibration is needed later, the system automatically retrieves these pre-stored reference values and uses them to calculate torque for any required pressure point, eliminating the need for manual recalibration at each pressure level.
Solution Approach 2:
The system creates a mathematical model (relational expression) that copies the pressure-torque relationship from the two calibrated reference points. This model is then used to estimate torque values for all other pressure points without physical measurement, effectively copying the relationship pattern rather than measuring each point individually.
2Reliability
If the welding pressure/torque relationship is recalibrated frequently due to servo motor deterioration and electrode tip wear, then the welding accuracy is maintained, but the operational downtime increases
Solution Approach 1:
The system performs preliminary calibration at only two reference pressure points, storing the torque values. When calibration is needed later, the system automatically retrieves these pre-stored reference values and uses them to calculate torque for any required pressure point, eliminating the need for manual recalibration at each pressure level.
Solution Approach 2:
The system performs automatic self-calibration using the stored reference values and the derived relational expression. The control device automatically calculates the required torque for any pressure point without requiring operator intervention or physical measurement equipment, enabling quick maintenance of welding accuracy with minimal operational downtime.
3Measurement precision
If manual calibration is performed for multiple pressure points, then accurate torque values are obtained, but the complexity and effort of calibration increase
Solution Approach 1:
The system performs preliminary calibration at only two reference pressure points, storing the torque values. When calibration is needed later, the system automatically retrieves these pre-stored reference values and uses them to calculate torque for any required pressure point, eliminating the need for manual recalibration at each pressure level.
Solution Approach 2:
The system creates a mathematical model (relational expression) that copies the pressure-torque relationship from the two calibrated reference points. This model is then used to estimate torque values for all other pressure points without physical measurement, effectively copying the relationship pattern rather than measuring each point individually.
Data Source
AI summary
A welding apparatus includes a module for prompting a user to input a command indicating that a welding pressure between a movable electrode tip and a fixed electrode tip has reached each of two welding pressures, a module for identifying a torque exerted in the servo motor and a movement amount of the movable electrode tip at a point in time when the command is input, a module for deriving a relational expression between the welding pressure and the movement amount, a module for using the relational expression to estimate a movement amount of the movable electrode tip required to generate another welding pressure, and a module for identifying a torque required for the movable electrode tip to move the estimated movement amount, and registering the torque in association with the another welding pressure.