3D Printing Nozzle With Active Mixing For Concrete
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Solution Overview
Problem
Current 3D printing methods for concrete and mortar face issues such as high unreacted material waste, low strength due to high water/cement ratios, low packing density, poorly defined edges, and slow construction processes, particularly in powder-based systems and pellet-based methods.
Innovation Solution
A 3D printer system with an actively driven mixer and nozzle design that allows for precise and homogeneous mixing of accelerators with concrete or mortar, enabling rapid setting and precise dispensing, along with a smoothing element to address surface finish and reinforcement integration for improved mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If powder-based 3D printing methods are used, then layer-by-layer construction is achieved, but high proportions of unreacted powdered material remain and water/cement ratios must be high resulting in low strengths
Solution Approach 1:
The invention changes the physical state of the concrete from powder to liquid/slurry form, and controls the water/cement ratio precisely through the mixing unit. This allows the concrete to be deposited in a controlled liquid state that maintains strength while enabling layer-by-layer construction.
Solution Approach 2:
The mixing unit acts as an intermediary between the concrete supply and the deposition point. It provides active mixing and precise control of the concrete's rheological properties, enabling the concrete to maintain appropriate consistency for 3D printing while preventing premature setting and ensuring high strength.
2Ease of operation
If dry powdered concrete is applied, then material can be stored and transported easily, but packing density is low and strength is reduced
Solution Approach 1:
The invention transforms the concrete from a dry powder state to a liquid/slurry state with optimized water/cement ratio. This parameter change increases the packing density and strength while the mixing unit ensures precise control of the liquid concrete's properties for optimal deposition.
3Productivity
If water or binder is printed selectively onto powdered concrete, then hardening occurs in printed areas, but edges are poorly defined and surface finish is rough
Solution Approach 1:
The mixing unit serves as an intermediary that provides active mixing and precise rheological control of the liquid concrete. This ensures the concrete maintains consistent flow properties during deposition, resulting in well-defined edges and smooth surfaces while enabling rapid hardening through controlled accelerator addition.
Solution Approach 2:
The invention changes the concrete delivery state from dry powder to controlled liquid/slurry with precise water/cement ratio. This parameter change enables the concrete to be deposited with sharp edges and smooth surfaces, while the mixing unit controls the hardening process for optimal productivity.
4Productivity
If accelerator is added to liquid concrete, then setting time is reduced and construction speed increases, but the accelerator must mix homogeneously throughout the concrete
Solution Approach 1:
The mixing unit employs active, dynamic mixing mechanisms that continuously agitate the liquid concrete as the accelerator is added. This dynamic mixing ensures homogeneous distribution of the accelerator throughout the concrete volume, enabling rapid and uniform setting that increases construction speed while maintaining precision.
5Productivity
If compressed air is used to atomize and accelerate shotcrete, then application speed increases, but the accelerator mixes only partly within the nozzle and partly during flight
Solution Approach 1:
The mixing unit acts as an intermediary mixing chamber that ensures complete homogeneous mixing of the accelerator with the liquid concrete before deposition. This active mixing mechanism guarantees 100% mixing completeness within the nozzle, eliminating the incomplete mixing that occurs with compressed air atomization methods.
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
Enables the creation of 3D printed objects with enhanced strength, reduced material waste, precise control over layer bonding, and improved surface finish, allowing for faster construction and increased mechanical stability through rapid setting and reinforcement integration.
Implementation Method 1
an actively driven mixing unit with a mixing tube is provided between the additional opening and the discharge opening
Implementation Method 2
the concrete, mortar or the like mixed with the accelerator can be dispensed from the discharge opening
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A nozzle (21) for dispensing concrete, mortar, or the like has a main opening (2) for supplying the concrete and at least one additional opening (3) for supplying an additive, in particular a setting accelerator, as well as a discharge opening (6). An actively driven mixing unit (24) with a mixing tube (1) is provided between the additional opening (3) and the discharge opening (6). According to the invention, in order to use such a nozzle for 3D printing, the inner diameter of the mixing tube (1) is a maximum of 8 cm, preferably a maximum of 6 cm, and in particular 2-4 cm. It is possible to design the process such that the concrete or mortar begins to stiffen already in the nozzle (21). Due to the thin mixing tube, concrete can be dispensed homogeneously, precisely, and with pinpoint accuracy from the nozzle.A valve (10) for temporarily stopping the material flow can be provided between the mixing unit (24) and the discharge opening (6) and/or the nozzle (21) can have an inlet (16) for compressed air for blowing out the concrete, so that the material discharge can be operated with compressed air as desired.