Servo Spot Welding Gun Position Correction via Torque Detection
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Solution Overview
Problem
In automated spot welding systems, deviations in workpiece position can lead to overload and improper welding current flow, degrading welding quality, and existing methods require complex and time-consuming position correction processes involving imaging devices.
Innovation Solution
A spot welding system with a pair of electrodes and a servo motor, integrated with a robot and control sections for switching between welding and position correction modes, uses physical quantity detection to determine electrode contact with the workpiece, allowing for automatic position correction without the need for imaging devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an imaging device is attached to the spot welding gun for position correction, then workpiece position detection is enabled, but the system complexity increases and correction speed decreases due to attachment/detachment operations
Solution Approach 1:
The patent extracts the imaging device from the spot welding gun, eliminating the need for attachment and detachment operations. Instead, the imaging device is positioned separately to capture workpiece images, while the spot welding gun remains independent for welding operations. This separation resolves the contradiction by maintaining position detection capability without the complexity of mounting mechanisms.
Solution Approach 2:
The patent introduces an intermediary processing system that receives images from the imaging device, computes workpiece position, and communicates correction data to the spot welding gun controller. This intermediary layer decouples the imaging function from the welding function, allowing independent optimization of each subsystem while maintaining coordinated operation.
2Measurement precision
If an imaging device is attached to the spot welding gun for position correction, then workpiece position detection is enabled, but the correction process time increases due to complex attachment and detachment operations
Solution Approach 1:
The patent implements preliminary positioning where the imaging device captures workpiece images before the spot welding gun approaches the workpiece. The position computation and correction data preparation are performed in advance, so when the welding operation begins, the gun is already positioned correctly, eliminating time-consuming attachment/detachment cycles during correction.
Solution Approach 2:
By extracting the imaging device from the welding gun assembly, the system eliminates the mechanical attachment and detachment operations that previously consumed significant time during position correction cycles, enabling faster correction without compromising detection accuracy.
3Productivity
If workpiece position is not checked before spot-welding, then the process is faster, but welding quality degrades due to overload and improper current flow
Solution Approach 1:
The system performs preliminary position verification by capturing workpiece images and computing position data before the spot welding operation begins. This preliminary action ensures that position correction is completed in advance, allowing the welding gun to proceed directly to welding without delays, thus maintaining both high productivity and welding quality.
Solution Approach 2:
The patent implements a feedback mechanism where the imaging device continuously monitors workpiece position, and the controller adjusts the welding gun position based on detected deviations. This closed-loop feedback ensures that welding operations always occur at the correct position, preventing overload and improper current flow while maintaining fast cycle times through automated real-time correction.
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
Enables quick and accurate position correction of workpieces, reducing operational complexity and costs by eliminating the need for imaging devices, while ensuring precise welding quality across different workpieces.
Implementation Method 1
a servo motor for allowing the pair of electrodes to approach each other and separate from each other
Implementation Method 2
a physical quantity detection section for detecting a physical quantity correlative to torque or velocity of the servo motor
Implementation Method 3
a position detection section for detecting positions of the pair of electrodes
Data Source
AI summary
A spot welding system including a spot welding gun having a pair of electrodes disposed opposite to each other, and a servo motor for allowing the pair of electrodes to approach each other and separate from each other; a robot for movably holding either a spot welding gun or a workpiece so that a workpiece is disposed between the pair of electrodes of the spot welding gun; a physical quantity detection section for detecting a physical quantity correlative to torque or velocity of the servo motor; a position detection section for detecting positions of the pair of electrodes; a mode switching section for switching, by a switching command, an operation mode of the spot welding system between a spot welding mode for spot-welding the workpiece and a position correction mode for correcting a spot welding position of the workpiece; and a processing section for performing a spot welding process in the spot welding mode and a position correction process in the position correction mode.