Robot Welding Torch Sensor Placement for Reduced Interference

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Solution Overview

Problem

Existing robot welding systems face interference issues due to the placement of welding sensors, which can obstruct the workpiece or surrounding devices when the torch body is curved, and require significant separation from the central axis to scan effectively, leading to increased protrusion and potential interference.

Innovation Solution

A robot system with a wrist mechanism featuring a rotatable flange, a welding torch with a tubular body curved three times to stabilize the arc, and a welding sensor positioned between the torch and the flange, allowing the sensor to scan parallel to the rotation axis, reducing interference by retracting the sensor from the torch body's distal end and minimizing radial protrusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the welding sensor is disposed in front of the torch body parallel to it, then the sensor can detect the weld line, but the sensor interferes with the workpiece or surrounding devices when the torch body is curved

Engineering Contradiction:

Improveweld line detectionVSAvoidinterference with workpiece

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The welding sensor is repositioned from a location in front of the torch body to a position between the flange and the torch fixed position, utilizing the radial dimension. The sensor scans along a plane parallel to the rotation axis, changing the scanning dimension from longitudinal to radial, thereby avoiding interference with the workpiece while maintaining detection capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Instead of placing the sensor in front of the torch body (conventional approach), the sensor is inverted to the opposite side - between the flange and torch fixed position. This inversion allows the sensor to scan the weld line from a position that does not interfere with the workpiece or surrounding devices

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If the sensor is separated significantly from the central axis to scan effectively, then the sensor can avoid interference, but the sensor protrusion increases leading to potential interference

Engineering Contradiction:

Improveinterference avoidanceVSAvoidsensor protrusion

Core Design Contradiction:

Object-affected harmful factorsVSLength of moving object

Solution Approach 1:

The sensor scanning plane is oriented parallel to the rotation axis rather than perpendicular to it, utilizing the radial dimension for scanning. This dimensional change allows the sensor to scan effectively while maintaining minimal protrusion from the torch body

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If the torch body is curved to stabilize the arc, then the wire contact is improved, but the sensor placement becomes more complex to avoid interference

Engineering Contradiction:

Improvearc stabilityVSAvoidsensor placement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The space between the flange and torch fixed position is utilized for dual purposes: it houses the welding sensor for weld line detection and simultaneously accommodates the curved torch body configuration for stable arc generation. This multi-functional use of the same spatial region simplifies the overall system design

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration reduces interference with workpieces and surrounding devices, enhances detection accuracy, and facilitates high-quality welding by positioning the sensor close to the rotation axis, minimizing vibrations and fouling, while maintaining stable arc generation.

Implementation Method 1

the welding sensor is capable of scanning a laser beam in a direction intersecting the weld line along a plane parallel to the rotation axis

Methodology Applied

Scientific EffectLaser beam scanning: Laser

Implementation Method 2

A wire passing through the interior of the torch body is curved in conformity to the curved shape of the torch body, and thus, it is possible to ensure stable contact between the wire and an inner surface of a power supply chip disposed at the distal end of the torch body, thereby stabilizing the generated arc

Methodology Applied

Scientific EffectCurved torch body wire contact stabilization:

Implementation Method 3

an arc welding torch used in robots includes a curved torch body

Methodology Applied

Scientific EffectElectric arc generation: Electric Arc

Data Source

PatentUS20240001473A1Robot system

Publication Date: 2024.01.04 FANUC LTD

AI summary

A robot system, including a robot having a wrist mechanism including a flange that is rotatable about a rotation axis, a welding torch fixed to the flange by a torch bracket, and a welding sensor that is fixed with respect to the welding torch and that detects a weld line, where the welding sensor is disposed at a position between the flange and a fixed position at which the welding torch is fixed to the torch bracket, the welding sensor is capable of scanning a laser beam, and the welding torch includes a tubular torch body that is arranged so as to protrude toward a distal end side than the fixed position, and makes a wire protrude from a distal end of the tubular torch body by the tubular torch body curved at least twice.