Convex Piston Surface for 3D Metal Printer Printhead
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Solution Overview
Problem
Piston designs with flat surfaces in 3D metal printers suffer from stagnation zones and gas inclusions, which hinder the movement of molten metal and lead to imprecise printing due to the high surface tension and density difference between metal and air, causing gas inclusions to remain and dampen pressure impulses.
Innovation Solution
A piston with a convex or conical pressure side surface that allows gas inclusions to slide off, combined with a guide sleeve and nozzle plate design that facilitates the discharge of gas inclusions into the reservoir, ensuring a uniform pressure build-up and improved actuation of the liquid metal phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flat surface piston is used, then the structure is simple and easy to manufacture, but gas inclusions accumulate on the piston surface forming stagnation zones
Solution Approach 1:
The piston surface is designed with a convex curvature instead of a flat surface. This curved geometry prevents gas inclusions from accumulating by eliminating stagnation zones, allowing gas to be pushed off the surface during piston movement while maintaining manufacturing feasibility.
2Reliability
If the piston moves vertically to discharge gas inclusions, then gas removal is improved, but the pressure impulse is dampened by remaining gas inclusions
Solution Approach 1:
The design extracts gas inclusions from the displacement space by utilizing the convex piston surface geometry. During vertical piston movement, gas inclusions are pushed off the convex surface and discharged into the reservoir, separating the gas removal function from the printing process to maintain pressure impulse integrity.
3Reliability
If complex work steps are implemented to remove gas inclusions, then gas discharge is improved, but the device complexity increases
Solution Approach 1:
The convex piston surface geometry enables self-service gas exclusion. The piston's own movement and geometry automatically discharge gas inclusions during normal operation without requiring additional complex mechanisms or work steps, maintaining device simplicity while improving reliability.
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
The design effectively reduces gas inclusions in the displacement space, enhancing the reproducibility and precision of the printing process by ensuring that gas inclusions are discharged, preventing their accumulation and allowing for improved actuation impulses.
Implementation Method 1
Depending on the viscosity of the liquid phase of the metal or melt and the buoyancy of the gas or air inclusions, these can slide past the surface of the plunger
Implementation Method 2
Since metallic melts have a very high surface tension, the very large difference in density between the air and the melt is often not sufficient to enable gas or air inclusions to rise
Implementation Method 3
If there are gas inclusions in the displacement space during the operation of the 3D printer, these act as a compressible medium and damp the pressure impulse of the plunger
Data Source
AI summary
The invention relates to a piston (5) for a printhead (1) of a 3D printer, particularly a metal printer, comprising a piston rod (17) and a ram (18), the ram (18) having a discharge side (19) that has a convex or tapering surface (39). The invention also relates to a printhead (1) for a 3D printer, particularly a metal printer, comprising a housing (3), a device (28) for supplying a metal (14), a reservoir (7, 27) for a liquid phase (8) of the metal (14), a nozzle device (2) comprising a guide sleeve (11) and a nozzle plate (9), and a piston (5) according to one of the preceding claims, the ram (18), the guide sleeve (11) and the nozzle plate (9) forming a displacement chamber (21), and the ram (18) and the guide sleeve (11) forming at least one area (40) for conducting the liquid phase (8) between the reservoir (27) and the displacement chamber (21).