Viscous Material Transfer Piston Design for Bone Cement Handling
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Solution Overview
Problem
Existing mixing apparatuses are inadequate for handling highly viscous materials like bone cement, which experience increased viscosity during polymerization, leading to insufficient shear force and inefficient mixing, especially in small batches.
Innovation Solution
A mixing apparatus with a stationary circumferential gear driving a planetary mixing element, combined with a central mixing element, that rotates and revolves to provide controlled shear force, along with a wiping element for efficient material transfer and separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional mixing apparatuses are used for highly viscous materials, then the mixing time increases, but the mixing efficiency and homogeneity deteriorate
Solution Approach 1:
The mixing system is segmented into multiple planetary mixing elements (at least two) that independently traverse circular paths around the central axis, each providing distinct mixing zones. This segmentation allows simultaneous mixing action at different locations, reducing overall mixing time while maintaining homogeneity through distributed shear force application.
Solution Approach 2:
The planetary mixing elements dynamically traverse circular paths around the central axis while rotating on their own axes. This dynamic motion creates varying shear forces throughout the viscous material, preventing stagnant zones and ensuring uniform mixing even in highly viscous conditions where conventional static mixers fail.
2Device complexity
If mixing apparatuses designed for liquid polymerization mixtures are used, then the device complexity remains low, but the mixing effectiveness deteriorates for highly viscous cements
Solution Approach 1:
The mixing apparatus uses multiple planetary mixing elements instead of a single central mixer, segmenting the mixing function across several components. This segmentation provides redundant mixing action and ensures that at least some mixing elements remain effective even as viscosity increases, maintaining reliability without requiring complex mechanical systems.
Solution Approach 2:
The planetary mixing elements act as intermediaries between the central mixing axis and the viscous material. These elements traverse circular paths and transfer shear force through the material in a controlled manner, enabling effective mixing of highly viscous cements without requiring excessive mechanical complexity or force.
3Loss of time
If high shear force is applied to increase mixing speed, then the mixing time decreases, but the material structure may be damaged
Solution Approach 1:
The planetary mixing elements apply shear force periodically as they traverse circular paths around the central axis. This periodic action distributes the mechanical stress over time and space, preventing concentrated force application that could damage material structure while still achieving rapid mixing through repeated shear cycles.
Solution Approach 2:
The mixing apparatus applies shear force locally at different positions around the central axis through multiple planetary elements. Each element creates localized mixing zones with controlled shear intensity, ensuring that no single region experiences excessive force that could damage the material structure while collectively achieving thorough mixing.
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 apparatus effectively mixes highly viscous materials with viscosities up to 500 Pascal/second within 90 seconds, ensuring complete mixing and efficient transfer of bone cement in small batches, even after the liquid phase has disappeared.
Implementation Method 1
A mixing apparatus with a stationary circumferential gear driving a planetary mixing element, combined with a central mixing element, that rotates and revolves to provide controlled shear force
Data Source
AI summary
An apparatus for transferring a viscous material comprising: a) a first container capable of containing a viscous material; b) a transfer piston insertable in the first container so that the piston forms a circumferential seal with respect to the container, the transfer piston including a hole; and c) a mechanism for attaching an aperture of a second container to the hole in the transfer piston wherein insertion of the transfer piston into the first container causes the viscous material to pass through the aperture into the second container.