Solid Propellant Additive Manufacturing Process
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Solution Overview
Problem
Existing methods for manufacturing solid propellants involve batch processes with significant delays and safety concerns due to transportation of raw materials and uncured propellant pieces between different locations, and long curing times.
Innovation Solution
A continuous additively manufacturing process where a propellant mixture is partially cured before dispensing, with the curing completed as the material cools after deposition, using a system comprising a mixer, dispenser, and heater to mix fuel, oxidizer, binder, and curative, and heat the mixture above its cure temperature before extrusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batch processes with separate mixing, casting, and curing locations are used, then manufacturing flexibility is maintained, but production time increases and safety risks arise from transporting uncured propellant
Solution Approach 1:
The patent combines mixing, casting, and curing operations into a single integrated additive manufacturing system. The propellant mixture is prepared, deposited layer-by-layer, and cured in-place within the same equipment, eliminating the need to transport uncured propellant between separate locations and thereby improving safety while reducing production time.
Solution Approach 2:
The additive manufacturing process enables continuous operation where mixing, deposition, and curing occur in an uninterrupted sequence within the same system. This continuous process eliminates idle transportation time and maintains the propellant in a controlled environment throughout manufacturing, addressing both safety and time efficiency concerns.
2Reliability
If traditional curing processes are used, then complete curing is achieved, but curing time extends to days or weeks
Solution Approach 1:
The patent applies localized heating during the additive manufacturing process to raise the temperature of the deposited propellant layers, accelerating the curing reaction. By controlling temperature parameters during deposition, the system achieves complete curing in a matter of hours rather than days or weeks, while maintaining curing completeness through controlled thermal processing.
3Ease of manufacture
If transportation of raw propellant mixture and uncured propellant pieces is required, then process flexibility is maintained, but safety precautions and handling risks increase
Solution Approach 1:
The patent integrates all manufacturing operations within a single additive manufacturing system, eliminating the need to transport raw propellant mixture or uncured propellant pieces between separate facilities. This consolidation maintains process flexibility while removing the safety hazards associated with handling and transporting reactive materials.
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 process reduces production time, minimizes handling risks, and eliminates the need for separate curing ovens, enabling faster and safer production of propellant pieces with improved efficiency and safety.
Implementation Method 1
heating the mixture above its cure temperature before extrusion
Implementation Method 2
the curing of the propellant piece may occur at a third location... the curing process taking days or weeks
Data Source
Figure 1~2
Figure 3~6
AI summary
A method of additively manufacturing propellant elements, such as for rocket motors, includes partially curing a propellant mixture before extruding or otherwise dispensing the material, such that the extruded propellant material is deposited on the element in a partially-cured state. The curing process for the partially-cured extruded material may be completed shortly after the material is put into place, for example by the material being heated at or above its cure temperature, such that it finishes curing before it fully cools. The propellant material may be prepared by first mixing together, a fuel, an oxidizer, and a binder, such as in an acoustic mixer. After that mixing a curative may be added to the mixture. The propellant mixture may then be directed to an extruder (or other dispenser), in which the mixture is heated to or above a cure temperature prior to the deposition, and then deposited.