Hatch Reversal Scanning for Stable Keyhole Transfer in 3D Printing
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Solution Overview
Problem
Existing additive manufacturing methods using laser sintering or melting experience increased material ejection (splashes) at the start of new hatch lines, leading to reduced mechanical properties of the manufactured object, particularly when using metal powder as the building material.
Innovation Solution
A method and device that generate control data for additive manufacturing apparatuses, specifying scanning trajectories for the laser beam with opposed directional components and controlled radiant flux transitions to minimize material ejection by overlapping initial and terminal points of adjacent solidification paths, ensuring a stable keyhole welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the laser beam is switched off at the end of a hatch line and switched on again at the start of the next hatch line, then the laser beam can be moved to the next position, but material ejection (splashes) occurs at the start of the new hatch line
Solution Approach 1:
The patent applies preliminary action by maintaining the laser beam in a ready state during the transition between hatch lines. The beam is not completely switched off but kept at a reduced power level or in a pre-heating mode, so that when the beam needs to start the next hatch line, the material is already prepared for solidification without requiring a full power activation that causes splashes.
Solution Approach 2:
Instead of switching the laser beam off and then on again (conventional approach), the patent inverts the approach by keeping the beam continuously active but modulating its power. The beam power is reduced during transitions and maintained or increased during solidification, reversing the conventional on/off cycle to a continuous modulated cycle that prevents material ejection.
2Object-generated harmful factors
If the laser beam is continuously active during hatch line transitions, then material ejection is reduced, but energy consumption increases
Solution Approach 1:
The patent applies periodic action by using a cyclic modulation of laser power that corresponds to the hatching pattern. The beam power is periodically increased during solidification phases and reduced during transition phases, creating a rhythmic on-off-like pattern that is smoother than complete switching. This periodic modulation maintains beam presence to prevent splashes while managing energy consumption through controlled power cycles.
Solution Approach 2:
The patent changes the laser beam power parameter dynamically during the manufacturing process. Instead of binary on/off states, the power is adjusted to intermediate levels during transitions and optimized levels during solidification. This parameter modulation allows the beam to remain active at lower energy consumption during transitions while delivering full energy when needed for material solidification.
3Reliability
If the initial point of a hatch line is positioned far from the terminal point of the previous hatch line, then the laser beam has sufficient time to stabilize, but the scanning path becomes longer and productivity decreases
Solution Approach 1:
The patent positions the initial point of each hatch line close to the terminal point of the previous hatch line, and applies preliminary action by pre-heating or pre-conditioning the material at these overlap regions before the main solidification passes. This allows the beam to start immediately without traveling a long stabilization distance, as the material is already prepared for solidification at the overlap zone.
Solution Approach 2:
The patent merges the end of one hatch line with the start of the next by creating overlap regions where the laser beam passes through the same area multiple times. The terminal point of one hatch line and the initial point of the next are positioned close together, and the beam trajectory is designed to overlap these regions, combining the stabilization function with the solidification function in a single continuous motion.
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
Improves the homogeneity and quality of the manufactured objects by reducing material ejection and enhancing the stability of the keyhole welding process, resulting in better mechanical properties.
Implementation Method 1
a laser beam is moved across those positions of a layer of the building material that correspond to the object cross-section of the object to be manufactured in this layer, so that the building material is solidified at these positions
Implementation Method 2
supplying heat energy to the building material by irradiating the same with electromagnetic radiation or particle radiation (e.g. laser sintering (SLS or DMLS) or laser melting)
Implementation Method 3
If radiant flux incident on an initial point of a solidification path is increased, then already close to the initial point a stable keyhole welding process can be reached
Implementation Method 4
more energy can then be introduced into the material due to multiple reflection at the sides of the vapor capillary. The temporarily formed vapor capillary is also designated as keyhole
Data Source
AI summary
Disclosed is a method for providing control data for manufacturing a three-dimensional object including accessing computer-based model data of at least one portion of the object, at least one data model specifying the scanning of locations of the region to be selectively solidified, using at least one beam along a first trajectory and a second trajectory substantially parallel thereto, the motion vectors of the beams in the construction plane having mutually opposite directional components during the scan along the two trajectories, and the distance between a starting point of the second trajectory and an end point of the previously scanned first trajectory is less than half a beam width of the beam at the end point of the first trajectory; and providing control data of the at least one data model for the generation of a control data set.