Weld Bead Deposition Planning for Defect-Free Path Intersections
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Solution Overview
Problem
The formation of additively manufactured objects by depositing weld beads often results in internal defects at intersection portions due to gaps and uneven deposition, requiring complex welding condition settings to prevent these issues.
Innovation Solution
A deposition planning method that classifies welding paths into intersection and constant regions, adjusts welding rates to balance deposit amounts between upper and lower layers, and ensures overlapping profiles of weld beads at intersections to maintain uniform deposition height and prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If weld beads are deposited along orthogonal paths to form intersection portions, then the three-dimensional shape can be constructed, but gaps form between weld beads and internal defects occur
Solution Approach 1:
The patent transitions from two-dimensional orthogonal path planning to three-dimensional path planning by introducing layer information. Welding paths are classified into upper layer paths and lower layer paths based on the Z-coordinate, allowing weld beads to be deposited in a staggered manner across different heights. This dimensional approach eliminates gaps by ensuring continuous material deposition throughout the intersection region, preventing internal defects while maintaining the ability to construct complex three-dimensional shapes.
2Manufacturing precision
If welding conditions are adjusted to prevent gaps at intersection portions, then internal defects are suppressed, but the setting becomes complex with many tuning parameters
Solution Approach 1:
The patent segments the welding path planning into distinct categories: upper layer paths and lower layer paths. This segmentation allows the system to apply different deposition strategies to different path types automatically. By classifying paths based on their spatial relationship (whether they form intersections and at what height), the complex problem of gap prevention is broken down into manageable segments with predetermined solutions, eliminating the need for manual tuning of multiple parameters.
Solution Approach 2:
The patent changes the fundamental parameter of path classification from simple two-dimensional trajectories to three-dimensional paths with layer assignments. By incorporating Z-coordinate information and classifying paths as upper or lower layer paths, the system automatically adjusts deposition parameters based on path type rather than requiring manual tuning. This parameter transformation simplifies the control system while maintaining high manufacturing precision.
3Productivity
If weld beads are deposited continuously without stopping, then productivity is improved, but uneven deposition and internal defects occur at intersection portions
Solution Approach 1:
The patent performs preliminary classification of welding paths into upper layer paths and lower layer paths before deposition begins. This advance planning allows the system to pre-determine the optimal deposition strategy for each path segment, ensuring uniform deposition height from the start. By calculating and assigning layer information in advance, the system maintains continuous deposition operations while preventing the formation of uneven surfaces and internal defects at intersection portions.
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 approach effectively prevents internal defects at intersection portions and ensures uniform bead deposition, simplifying the setting of welding conditions and improving the quality of additively manufactured objects.
Implementation Method 1
an additive manufacturing apparatus that deposits weld beads obtained by melting and solidifying a filler metal
Implementation Method 2
the additively manufactured object is formed using shape data representing a three-dimensional shape of the additively manufactured object by an additive manufacturing apparatus that deposits weld beads
Data Source
AI summary
A deposition planning method for an additively manufactured object includes: acquiring shape data; determining a welding path of each layer by slicing a three-dimensional shape of the additively manufactured object into layers; classifying a plurality of welding paths into intersection region paths and constant region paths; dividing the intersection region paths into a lower layer path and an upper layer path of an intersection portion; and determining welding conditions of the intersection region paths such that an upper layer deposit amount is more than a lower layer deposit amount, a sum of the upper layer deposit amount and the lower layer deposit amount is equal to a deposit amount in the constant region paths, and in a cross-section orthogonal to a longitudinal direction of the weld beads formed along the upper layer path, profiles of the weld beads adjacent to each other overlap each other.