Weld Bead Shape Sensing for Adaptive Laminate Molding Control
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Solution Overview
Problem
In additively-manufactured objects, accurately controlling the width or height of weld beads is challenging, especially when measuring internal built portions, due to obstacles and variations in position information, which complicates feedback control for achieving the desired shape and welding amount.
Innovation Solution
A system that includes a torch on a robot arm with a shape sensor for non-contact measurement of weld bead shapes, a switching unit to adjust measurement output based on weld bead shape and position information, and a correction unit to adjust deposition conditions based on measured data and the deposition plan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If position information of internal built portions is measured using laser sensors, then feedback control for weld bead shape can be performed, but the frame portion becomes an obstacle making measurement difficult and increasing position information variation
Solution Approach 1:
The patent introduces a coordinate transformation mechanism as an intermediary that converts measurement data from the sensor's coordinate system to the workpiece's coordinate system. This allows accurate measurement of internal built portions even when the sensor is positioned externally, as the coordinate transformation compensates for the frame portion obstacles and enables precise feedback control without direct line-of-sight measurement.
2Manufacturing precision
If weld bead height is controlled within tolerance range, then quality of built object is improved, but additional weld beads must be formed or removed increasing manufacturing complexity
Solution Approach 1:
The patent implements a feedback control system where the shape sensor measures the actual weld bead height, compares it with the target height, and adjusts subsequent welding parameters accordingly. This closed-loop feedback enables precise weld bead height control within tolerance ranges without requiring additional weld beads or removal operations, as the welding process self-corrects based on real-time measurement data.
Solution Approach 2:
The patent dynamically adjusts welding parameters such as travel speed, wire feed rate, and heat input based on real-time measurements of weld bead morphology. This dynamic adaptation allows the system to maintain optimal weld bead dimensions throughout the additive manufacturing process, preventing deviations that would otherwise require post-processing corrections.
3Adaptability or versatility
If non-contact measurement is used for weld bead shape, then manufacturing of objects with complex configurations can be achieved, but accurate acquisition of required welding amount information becomes difficult due to position variations
Solution Approach 1:
The patent employs coordinate transformation that maps three-dimensional measurement data from the sensor's perspective into the workpiece's reference coordinate system. This dimensional transformation allows accurate reconstruction of weld bead geometry and calculation of required welding amounts, even when measurements are taken from external positions around complex configurations, thereby preserving complete geometric information.
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 system enables the accurate and consistent manufacturing of additively-manufactured objects with desired shapes, regardless of the object's configuration, by effectively controlling weld bead dimensions and deposition conditions.
Implementation Method 1
a shape sensor attached to the torch measures, in a non-contact manner, a shape of the weld bead that is deposited
Data Source
Figure 1
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Figure 4(A)~4(B)
AI summary
This system for manufacturing a laminate molded product comprises: a torch provided to a robot arm; a measurement unit that contactlessly measures the shape of a laminated welding bead by using a shape sensor attached to the torch and that outputs measurement information pertaining to a representative height of the welding bead and/or the cross-sectional area of the welding bead; a switching unit that, on the basis of the shape of the welding bead and/or position information pertaining to the welding bead as retained in a lamination plan, switches between the measurement information items outputted by the measurement unit; and a correction unit that corrects the conditions for laminating the welding bead on the basis of the measurement information and the lamination plan.