Agent Distributor Alignment via Height Profile Detection

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Solution Overview

Problem

Existing additive manufacturing systems face challenges in accurately aligning agent distributors, such as printheads, during the generation of three-dimensional objects, particularly in powder-based build materials, which affects the precision and quality of the printed objects.

Innovation Solution

The method involves forming a predetermined alignment pattern on the build material using a coalescing agent or coalescence modifier agent, detecting the resulting height profile caused by the agent's interaction with the material, and using this information to align the agent distributor. This process utilizes height sensors to compare the detected pattern with a known alignment pattern, allowing for adjustments to ensure accurate alignment without relying on back-and-forth movement of a support bed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional alignment methods using back-and-forth movement of support bed are used, then the alignment process is simple, but the alignment accuracy and manufacturing precision deteriorate

Engineering Contradiction:
Improvealignment accuracyVSAvoidalignment process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical alignment method (back-and-forth movement of support bed) with an optical detection system. Height sensors detect the alignment pattern deposited on the build material surface, and the system calculates alignment offsets based on the detected pattern geometry, eliminating the need for mechanical movement and achieving higher precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an alignment pattern as an intermediary element. This pattern is deposited on the build material and serves as a reference for the height sensors to detect misalignment. The pattern acts as a mediator between the agent distributor and the detection system, enabling precise alignment measurement without direct mechanical interaction.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If height sensors and alignment patterns are introduced to improve alignment precision, then manufacturing precision improves, but device complexity increases

Engineering Contradiction:
Improveagent distributor alignmentVSAvoidalignment system components
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system uses the build material surface itself as the detection medium. The height sensors detect the alignment pattern directly on the build material surface, utilizing the existing workspace rather than requiring separate calibration substrates or additional measurement surfaces. This self-service approach reduces the need for external alignment tools.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The build material surface serves multiple functions: it is both the substrate for building the 3D object and the medium for detecting agent distributor alignment. The alignment pattern is deposited on the same surface where the actual printing occurs, eliminating the need for separate alignment calibration surfaces or additional components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Manufacturing precision

If alignment pattern detection is performed on build material surface, then alignment accuracy improves, but the process requires additional steps affecting productivity

Engineering Contradiction:
Improvealignment detection accuracyVSAvoidprinting process efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The alignment pattern is deposited on the build material surface before the actual printing process begins. The height sensors detect this pre-deposited pattern to determine alignment offsets, and the agent distributor is adjusted accordingly before production printing starts. This preliminary alignment step ensures accurate printing from the beginning without requiring interruptions during the printing process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent performs alignment detection and adjustment in a rapid preliminary step before the main printing process. By completing the alignment calibration quickly using the alignment pattern and height sensors, the system minimizes the time added to the overall process while ensuring high precision for the subsequent production printing.

Inventive Principle:
Principle #21Skipping (Rushing through)

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 enhances the accuracy and precision of the printing process by using the interaction between the agent and build material to create a detectable height profile, enabling precise alignment of the agent distributor and improving the definition and surface quality of the printed objects.

Implementation Method 1

selectively delivering an agent (for example a coalescing agent and/or a coalescence modifier agent) to one or more portions of a surface of the layer of build material... portions of the build material on which coalescing agent has been delivered or has penetrated to heat up above the melting point of the build material and to coalesce

Methodology Applied
Scientific EffectCoalescence: Coagulation

Data Source

PatentEP3200974B1Aligning an agent distributor
Publication Date: 2020.09.23 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3200974B1 patent drawingFigure 1
  • EP3200974B1 patent drawingFigure 2a~2c
  • EP3200974B1 patent drawingFigure 2d

AI summary

A method of aligning an agent distributor in an apparatus for generating a three-dimensional object comprises selectively depositing an agent on a layer of build material to form a predetermined alignment pattern (211, 212, 311, 312), and detecting the alignment pattern (211, 212, 311, 312) from a height profile in a surface of the build material, and performing an alignment operation using the detected alignment pattern (211, 212, 311, 312). An alignment pattern (211, 212, 311, 312) may comprise, for example, a series of triangles which are scanned to determine misalignment.