3D Concrete Printhead Segmentation for Clogging and Mixing
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Solution Overview
Problem
Existing 3D concrete printing technologies face challenges such as clogging, inefficient gas integration, and uneven mixing due to the use of high pressures and stiff granular mediums, which affect the quality and consistency of the final product.
Innovation Solution
The development of a printhead design that facilitates high-pressure in-line mixing of fluids with stiff granular mediums, accommodating particles of variable sizes without proportional pressure increases, and minimizing cleaning efforts and pressure losses. This design includes a convergent-divergent section and shearing blades to promote mixing and interaction between primary and secondary fluids, with a regulator device to control the secondary fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure is used to pump stiff granular mediums through the printhead, then the material can be delivered, but clogging occurs and pressure losses increase
Solution Approach 1:
The printhead is divided into multiple chambers (first chamber for primary fluid, second chamber for secondary fluid) with separate inlet ports. This segmentation allows granular material to flow through one chamber while gas flows through another, preventing clogging in the granular material pathway while maintaining delivery capability.
Solution Approach 2:
A gas permeable barrier acts as an intermediary between the primary fluid chamber and secondary fluid chamber. This barrier allows gas to pass through while preventing granular material from entering the gas chamber, enabling material delivery without clogging the gas pathways.
2Adaptability or versatility
If high pressure is increased to accommodate larger particles, then particle size range increases, but pressure losses increase proportionally
Solution Approach 1:
The printhead separates granular material flow and gas flow into different chambers. This allows the system to accommodate variable particle sizes in the primary fluid chamber without requiring proportional pressure increases, as the gas injection pathway remains independent and is not blocked by particle size variations.
3Stability of the object's composition
If gas is injected into stiff granular medium at high pressure, then mixing is improved, but clogging and safety risks increase
Solution Approach 1:
The printhead segments the injection process into two independent streams: granular material through the first chamber and gas through the second chamber. This segmentation enables effective mixing upon convergence while preventing clogging by keeping the gas pathway separate from the granular material pathway, reducing safety risks associated with high-pressure gas injection into dense material.
Solution Approach 2:
The gas permeable barrier serves as an intermediary that allows controlled gas transfer while preventing granular material from entering the gas chamber. This intermediary function maintains mixing effectiveness while eliminating clogging risks in the gas injection system.
4Device complexity
If conventional printhead design is used, then structure is simple, but cleaning efforts and maintenance are required
Solution Approach 1:
The printhead is segmented into distinct chambers with separate inlet ports for primary and secondary fluids. This segmentation allows for easier cleaning and maintenance of each chamber independently, reducing overall cleaning effort despite the increased structural complexity of having multiple chambers and a permeable barrier.
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 printhead design achieves accelerated carbonation of cementitious mixtures, enhancing the buildability and mechanical properties of 3D printed concrete, such as increased compressive strength, flexural stiffness, and refined pore structure, while reducing operational inefficiencies and safety risks.
Implementation Method 1
The shearing blade is configured to provide shear force onto the primary fluid and the secondary fluid, thereby promoting mixing of and interaction between the primary fluid and the secondary fluid
Implementation Method 2
The main body defines an inner bore extending from the first inlet to the outlet nozzle, wherein the inner bore includes a convergent-divergent section
Implementation Method 3
direct carbonation of fluid cementitious materials by use of an attachment design... carbon dioxide used to carbonate cement in the described additive manufacturing processes and systems can be sourced from carbon dioxide that has been captured from other processes
Data Source
AI summary
A printhead for three-dimensional printing of concrete includes a main body and a regulator device. The main body includes a multi-stage, convergent-divergent cylinder, shearing blades, a pressure chamber, and a secondary inlet. The pressure chamber surrounds the cylinder for temporary storage and regulated processing of a secondary fluid. The secondary inlet transfers the secondary fluid from the pressure chamber to the multi-stage, convergent-divergent cylinder to form a mixture, which is discharged from the printhead. The printhead can, for example, be used for additive manufacturing of cement-based materials.