Bone Cement Mixing System with Sieve and Shield
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Solution Overview
Problem
Current bone cement mixing systems face issues with incomplete mixing, air inclusions, and clogging due to the transfer of bone cement powder into the monomer liquid, leading to unpredictable mechanical properties and inefficiencies in the mixing process.
Innovation Solution
A bone cement system with a sieve element and a dispensing opening having a specific ratio of through-opening to sieve element area, along with a distance between the shield and sieve element, ensures complete monomer transfer and prevents cement powder ingress into the conveyor, using a vacuum to aspirate air and monomer liquid, and a funnel-shaped dispensing opening for efficient mixing and dispensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sieve element is arranged between the reservoir container and mixing facility to prevent cement powder ingress, then clogging is prevented, but incomplete mixing occurs due to poor monomer distribution
Solution Approach 1:
The mixing facility is divided into multiple mixing chambers (first mixing chamber and second mixing chamber) separated by a partition wall with through-openings. The sieve element is positioned in the first mixing chamber while the shield with through-openings is in the second mixing chamber. This segmentation allows the monomer to be distributed through controlled openings while maintaining separation between the powder and liquid phases initially, then mixing them homogeneously in the second chamber.
Solution Approach 2:
The partition wall with through-openings acts as an intermediary structure between the first and second mixing chambers. It allows the monomer liquid to pass from the first chamber (where the sieve prevents powder ingress) to the second chamber (where the shield provides additional flow control). This intermediary structure enables both clogging prevention and homogeneous mixing by controlling the flow path of the monomer.
2Manufacturing precision
If vacuum mixing is used to remove air inclusions, then cement quality is improved, but air in the conveyor causes destabilization during storage
Solution Approach 1:
The mixing facility is designed with a dispensing opening that allows the mixed bone cement to be extracted or taken out from the mixing chambers. The shield with through-openings and the sieve element work together to ensure that during storage, the mixed cement remains in the mixing facility under controlled conditions, preventing air ingress into the conveyor system while allowing complete removal during dispensing.
3Device complexity
If tubes are used to introduce monomer liquid into cement powder, then mixing is simplified, but cement powder clogs the tubes during storage
Solution Approach 1:
Instead of introducing the monomer liquid through tubes into the cement powder (which causes clogging), the invention inverts the approach by having the monomer liquid flow over the sieve element and through the shield with through-openings in a controlled manner. The monomer is introduced from the reservoir container through the sieve and shield structures, allowing liquid flow without powder ingress, thus preventing clogging while maintaining mixing simplicity.
4Productivity
If the shield has large through-openings for efficient monomer flow, then mixing speed increases, but cement powder may pass through causing clogging
Solution Approach 1:
The flow control is segmented into two stages: the sieve element in the first mixing chamber with small openings that prevent powder passage, and the shield with larger through-openings in the second mixing chamber that allows efficient monomer flow. This segmentation enables the system to achieve both high productivity (through the larger openings) and reliable clogging prevention (through the sieve element).
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 solution ensures complete and homogeneous mixing of bone cement, preventing clogging and maintaining consistent mechanical properties by ensuring all monomer interacts with the cement powder before it solidifies, resulting in a more reliable and efficient bone cement application.
Implementation Method 1
using a vacuum to aspirate air and monomer liquid
Implementation Method 2
swelling of the polymers of the powder component in the methylmethacrylate leads to the formation of a dough
Implementation Method 3
the activator, N,N-dimethyl-p-toluidine, reacts with dibenzoylperoxide while forming radicals. The radicals thus formed trigger the radical polymerization of the methylmethacrylate
Data Source
AI summary
A bone cement system (100) is provided having a mixing facility (10) for mixing and dispensing of bone cement, a reservoir container (112) for a monomer, and a conveyor (122). The mixing facility (10) has a mixing cylinder (20), which stores a bone cement powder. The monomer can be conveyed from the reservoir container (112) into the mixing cylinder (20) by the conveyor (122). A sieve element is (4) is arranged between the reservoir container (112) and the mixing facility (10), in order to prevent ingress of the bone cement powder from the mixing cylinder (20) into the conveyor (122). The mixing device (10) included a dispensing opening (23) for dispensing a bone cement mixed from the bone cement powder and the monomer. The dispensing opening (23) includes a shield (1) having at least one through-opening (2). The ratio of the area of the through-opening (2) to the area of the sieve element (4) is at least 1 to 3, and the distance between the shield (1) and the sieve element (4) is at least 1 mm.