Weld Bead Deposition Control Using Laser and Arc Signal Feedback
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Solution Overview
Problem
Existing methods struggle to precisely control the width and height of weld beads in additively-manufactured objects due to limitations in laser sensor measurement and feedback control, particularly when the laser sensor is obstructed by the object being manufactured.
Innovation Solution
A system utilizing a first measurement unit, such as a laser sensor, and a second measurement unit, which measures current, voltage, and filler metal supply rate, to indirectly determine the base shape, allowing for switching between measurement methods based on threshold values and depositing plan information to maintain precise control over weld bead formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a laser sensor is used to directly measure base shape for feedback control, then measurement precision is improved, but the measurement may be obstructed by the object being manufactured
Solution Approach 1:
The patent introduces an intermediary measurement approach by using electrical measurements (current, voltage, filler metal supply rate) as a mediator to indirectly obtain base shape information when direct laser measurement is obstructed. This intermediary method allows the system to bypass the obstruction problem while still achieving the measurement objective.
Solution Approach 2:
The patent changes the measurement parameter from direct optical measurement to indirect electrical parameter measurement. By monitoring changes in current, voltage, and filler metal supply rate, the system infers base shape information without requiring direct line-of-sight measurement, thus avoiding obstruction issues.
2Measurement precision
If only laser sensor measurement is used, then direct base shape measurement is achieved, but feedback control reliability deteriorates when obstruction occurs
Solution Approach 1:
The patent implements a dynamic measurement system that can switch between different measurement methods based on real-time conditions. The system dynamically selects between laser sensor measurement and electrical parameter-based indirect measurement, ensuring reliable feedback control regardless of obstruction status.
Solution Approach 2:
The patent performs preliminary determination of the base shape using electrical measurements before weld bead deposition begins. This preliminary action provides advance information about the base geometry, allowing the system to prepare appropriate welding parameters and ensuring control reliability even if subsequent laser measurements are obstructed.
3Reliability
If indirect measurement using electrical parameters is used, then measurement reliability is improved under obstruction, but measurement precision may deteriorate compared to direct laser measurement
Solution Approach 1:
The patent merges two different measurement approaches - direct laser sensor measurement and indirect electrical parameter measurement - into a unified feedback control system. By combining the advantages of both methods and selecting the appropriate one based on measurement quality and obstruction status, the system achieves both high precision and high reliability.
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 the production of additively-manufactured objects with high precision by selecting appropriate measurement results from either the laser sensor or electrical measurements, ensuring accurate control of weld bead shape and position even when laser sensors are obstructed.
Implementation Method 1
a first measurement unit that is mounted on the torch and that directly measures, in a non-contact manner, a base shape of a base portion on which the weld beads are deposited
Implementation Method 2
manufacturing an additively-manufactured object obtained by depositing a plurality of weld beads formed by melting and solidifying a filler metal using an arc on a base material
Data Source
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AI summary
Provided is a system for manufacturing a laminate molded product in which weld beads are laminated on the basis of a laminate plan, the system comprising: a torch provided to a robot arm; a first measuring unit constituting a shape sensor that is mounted on the torch and that directly measures, without contact, an underlayer shape of an underlayer portion in which the weld beads are laminated; a second measuring unit that measures at least one of an electric current, voltage, and a filler material feeding speed when laminating the weld beads, and that estimates an underlayer shape from the history change thereof; and a control unit that selects measurement results of at least either the first measuring unit or the second measuring unit, and that modifies the control of at least one of the robot arm, electric current, voltage, and filler material feeding speed.