3D Printing Pre-Heating Beam Scanning for Discharge Prevention
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Solution Overview
Problem
The use of electron beams in three-dimensional object production with powdery materials is hindered by electrical discharges due to charge distribution, which can destroy the structure of the powder layer, and adding conductive materials to prevent discharges complicates the solidifying process and reduces mechanical strength.
Innovation Solution
A method involving a pre-heating step where the powdery material is scanned with a high-energy beam along paths separated by a minimum security distance to prevent summation effects, increasing electrical conductivity and avoiding discharges, while also allowing for efficient heating without additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electron beam is applied to melt/sinter powder, then the powder can be fused together to form three-dimensional objects, but electrical discharges occur due to charge distribution which destroys the powder layer structure
Solution Approach 1:
The patent applies a preliminary action by pre-heating the powder layer with the electron beam before applying the main melting/sintering beam. This pre-heating step raises the powder temperature to a level where electrical conductivity increases, which prevents electrical discharges during the subsequent main processing step. The pre-heating is performed in a controlled manner with the beam scanning along paths separated by minimum security distances to ensure homogeneous heating without creating excessive charge density.
Solution Approach 2:
The patent changes the temperature parameter of the powder layer during the pre-heating step, raising it from ambient temperature to a elevated temperature range. This parameter change (temperature increase) fundamentally alters the electrical conductivity of the powder, transforming it from an insulating state to a conductive state, thereby preventing electrical discharges during the main sintering process.
2Object-affected harmful factors
If conductive material is added to the powder to prevent discharges, then electrical conductivity increases and discharges are avoided, but the solidifying process becomes difficult to control and mechanical strength decreases
Solution Approach 1:
The patent applies self-service by utilizing the powder material itself to generate the necessary electrical conductivity through temperature-induced conductivity enhancement. Instead of adding external conductive materials, the powder's own properties are exploited - when heated to the pre-heating temperature range, the powder particles become sufficiently conductive to prevent discharges during electron beam processing. This eliminates the need for additive materials that would compromise mechanical strength.
3Manufacturing precision
If the beam scans along paths separated by minimum security distance to prevent summation effects, then homogeneous heating is achieved, but the pre-heating process time increases
Solution Approach 1:
The patent applies segmentation by dividing the pre-heating process into multiple scanning passes over the powder layer. The beam scans along a series of parallel paths separated by minimum security distances, and this segmented scanning pattern is repeated for multiple passes. This segmentation ensures that every region of the powder layer receives uniform energy distribution, achieving homogeneous heating while controlling the total process time through optimized scanning parameters.
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 ensures homogeneous heating, prevents large temperature gradients and discharges, and allows for higher beam currents during solidification, resulting in a controlled and efficient fusion process without the need for extra heating equipment.
Implementation Method 1
a pre-heating step with the general purpose of pre-heating the powdery material in a homogeneous manner
Implementation Method 2
the pre-heating step allows the powder layer to be homogenously heated up so as to avoid having too large temperature gradients
Implementation Method 3
As the electron beam hits the powder, a charge distribution develops around the electron target area. If the charge distribution density exceeds a critical limit, an electrical discharge will occur
Implementation Method 4
an electrical discharge will occur since the powder particles will repel each other
Implementation Method 5
the pre-heating step allows the powder layer to be homogenously heated up so as to avoid having too large temperature gradients... increases the electrical conductivity of the powder
Implementation Method 6
The powder sinters or melts and solidifies as the beam moves over the working area
Implementation Method 7
When melting or sintering a powder using a high-energy beam
Data Source
Figure 1
Figure 2
Figure 3a~3c
AI summary
The invention concerns a method for producing three-dimensional objects (3) layer by layer using a powdery material (5) which can be solidified by irradiating it with a high-energy beam. The inventive method comprises a pre- heating step with the general purpose of pre-heating the powdery material (5) in a homogeneous manner, followed by a solidifying step with the general purpose of fusing together the powdery material, wherein the pre-heating step comprises the sub-step of scanning a pre-heating powder layer area (10) by scanning the beam along paths (P1.1 - P5.20) distributed over the pre-heating powder layer area (10), wherein consecutively scanned paths (PM. N, P(M+1 ).N) are separated by, at least, a minimum security distance (?Y), said minimum security distance (?Y) being adapted to prevent undesirable summation effects in the pre-heating powder layer area (10) from said consecutively scanned paths. The invention also concerns a device adapted to be operated by the inventive method.