Spot Welding Gun Position Detection via Variable Electrode Speed

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Solution Overview

Problem

Conventional spot welding systems face challenges in accurately detecting the position of a workpiece due to varying rigidity and posture at different welding points, leading to prolonged detection times and reduced accuracy, as they use constant parameters for all points without considering specific conditions.

Innovation Solution

A spot welding system with a control device that sets and updates workpiece detection parameters, including movement speed and abutment judgement values, specifically for each welding point based on the state values of the electrode drive motor, allowing for precise position detection by adjusting parameters according to the unique conditions of each welding point.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If constant parameters are used for position detection control at all welding points, then the control system is simple and easy to operate, but the detection time is prolonged and detection accuracy decreases

Engineering Contradiction:

Improveease of operationVSAvoiddetection time

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the movement speed of the movable electrode variable according to the welding point conditions. The control device sets different movement speeds based on the rigidity and posture at each welding point, allowing the system to adapt dynamically rather than using a fixed constant speed for all positions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of movement speed based on the specific conditions at each welding point. By adjusting the movement speed parameter according to workpiece rigidity and electrode posture, the system optimizes detection time and accuracy for each position while maintaining operational simplicity through automated parameter management.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If constant parameters are used for position detection control at all welding points, then the control system is simple, but the detection accuracy decreases

Engineering Contradiction:

Improveease of operationVSAvoidposition detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies local quality by setting specific movement speed parameters for each welding point based on local conditions such as workpiece rigidity and electrode posture. Each welding point receives optimized parameters tailored to its specific characteristics, improving detection accuracy at each location while the control device manages the complexity automatically.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the movement speed parameter according to the specific conditions at each welding point. By adjusting this parameter based on local rigidity and posture variations, the system achieves high detection accuracy at each position without requiring manual intervention to set the parameters.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If high movement speed is used for position detection, then the detection time is shortened, but the detection accuracy deteriorates

Engineering Contradiction:

Improvedetection efficiencyVSAvoidposition detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by adjusting the movement speed according to the specific conditions at each welding point. For welding points with higher rigidity and favorable posture, higher speeds are used to improve efficiency. For points with lower rigidity or difficult posture, lower speeds maintain accuracy, achieving an optimal balance dynamically.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the movement speed parameter based on the relationship between detection speed and accuracy. By optimizing this parameter for each welding point's specific conditions, the system achieves high detection efficiency without sacrificing accuracy at any position.

Inventive Principle:

Principle #35Parameter changes

4Loss of time

If the movement speed of the movable electrode is increased, then the detection time is reduced, but erroneous judgments increase

Engineering Contradiction:

Improvedetection timeVSAvoiddetection reliability

Core Design Contradiction:

Loss of timeVSReliability

Solution Approach 1:

The patent changes the movement speed parameter according to the specific conditions at each welding point to optimize the balance between detection time and reliability. By setting appropriate speeds for each position, the system reduces detection time while minimizing erroneous judgments through condition-appropriate parameter selection.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10146203B2Spot welding system for measuring position of welding point at which welding is performed

Publication Date: 2018.12.04 FANUC LTD

AI summary

A spot welding system comprises a robot which changes a relative position of a spot welding gun and a workpiece. A control device drives an electrode drive motor so that a movable electrode of the spot welding gun abuts on the workpiece, and is formed so as to perform a position detection control which detects a position of the workpiece based on a position of the movable electrode when a state value of the electrode drive motor deviates from a predetermined range. An operation program includes a workpiece detection parameter for performing the position detection control. The workpiece detection parameter is set at each of welding points in the operation program.