MHD Pump Induction Heating for Liquid Metal 3D Printing
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Solution Overview
Problem
Magnetohydrodynamic (MHD) 3D printers face challenges in maintaining consistent drop temperatures during transitions between standby and print modes, leading to temperature transients that affect the bonding and mechanical properties of printed parts.
Innovation Solution
Implementing sub-threshold pulsing of the MHD actuation coil, which generates induction heating without ejecting droplets, to maintain consistent temperatures in the pump during both modes, using specific time varying current pulses with varying frequencies, pulse widths, and voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the MHD pump is pulsed only when drops are jetted in standby mode, then energy consumption is reduced, but drop temperature transients occur during mode transitions
Solution Approach 1:
The system applies a preliminary sub-threshold pulse before the main jetting pulse to pre-heat the liquid metal in the pump. This preliminary action ensures that the liquid metal reaches the required temperature before actual jetting occurs, eliminating temperature transients during mode transitions while maintaining energy efficiency.
Solution Approach 2:
The system uses periodic sub-threshold pulses during standby mode to maintain continuous, low-level heating of the liquid metal. This periodic action prevents temperature drops during idle periods without requiring continuous high-power operation, thus maintaining temperature consistency while managing energy consumption.
2Temperature
If induction heating is applied during print mode, then drop temperature is maintained, but temperature spatial profiles become non-uniform
Solution Approach 1:
The system applies induction heating locally to specific regions of the pump chamber where liquid metal is present, rather than heating the entire pump uniformly. By targeting only the necessary areas with sub-threshold pulses, the system maintains drop temperature while minimizing non-uniform temperature profiles in the pump chamber.
3Temperature
If the pump heater is used to maintain temperature in standby mode, then temperature control is achieved, but temperature transients occur during mode switching
Solution Approach 1:
The system uses a preliminary sub-threshold pulse applied before the main jetting operation to pre-condition the liquid metal temperature. This preliminary heating action ensures that when the pump switches from standby to print mode, the liquid metal is already at the required temperature, eliminating transients during mode switching while maintaining effective temperature control.
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 mitigates drop temperature transients, ensures consistent temperatures within the pump, and improves the bonding and mechanical properties of printed parts by maintaining higher drop temperatures during printing.
Implementation Method 1
an actuation coil configured to supply a pulse to the liquid metal to generate an electromagnetic force upon the liquid metal, where the actuation coil supplies a pulse at a first time varying current pulse, and where the electromagnetic force causes the nozzle to eject a drop of liquid metal
Implementation Method 2
the actuation coil also supplies a pulse at a second time varying current pulse, where the electromagnetic force is not sufficient to eject a drop of liquid metal through the nozzle. When the actuation coil supplies a pulse at a second time varying current pulse, a temperature in an upper portion of the pump is from about 800° C. to about 850° C., a temperature in a lower portion of the pump is from about 800° C. to about 850° C.
Implementation Method 3
The metal or metal alloy in the pump is maintained in a molten state using a resistive heating element
Data Source
AI summary
A printer having a pump which includes an inner cavity which retains a liquid metal printing material, and a nozzle, where the nozzle is configured to eject a plurality of liquid metal drops, an actuation coil configured to supply a pulse to the liquid metal to generate an electromagnetic force upon the liquid metal, where the actuation coil supplies a pulse at a first time varying current pulse, where the electromagnetic force causes the nozzle to eject a drop of liquid metal. The actuation coil also supplies a pulse at a second time varying current pulse, where the electromagnetic force is not sufficient to eject a drop of liquid. A method for metal jetting in a printer is also disclosed where differences between the temperature in an upper portion of the pump and the temperature in a lower portion of the pump are minimized.