Magnetic Preload Cutting Tool Eliminates Thrust Washers
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Solution Overview
Problem
Current surgical cutting instruments face issues with inconsistent preload force due to dimensional variations, reliance on thrust washers that can break down and cause seizing, and size limitations in small diameter applications, leading to retention problems and increased maintenance.
Innovation Solution
The use of permanent magnets with different polarities between the outer and inner tubular members to create a controlled preload force, eliminating the need for thrust washers and allowing for precise control of the preload force, regardless of hand piece unit engagement, and incorporating a retention feature to maintain the inner tubular member's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a compression spring and housing assembly are integrated into the inner tubular member, then the inner tubular member can be preloaded against the outer tubular member, but the design becomes complex and size limitations are imposed
Solution Approach 1:
The patent extracts the compression spring and housing assembly from the inner tubular member design, replacing them with a magnet-based preload mechanism. This removes the complex mechanical components while maintaining the preload function through magnetic attraction forces between magnets positioned on the inner and outer tubular members.
Solution Approach 2:
The patent replaces the mechanical compression spring system with a magnetic field-based system. Magnets are positioned on both the inner and outer tubular members to create attractive forces that provide the necessary preload, eliminating the need for mechanical springs and housing assemblies.
2Force
If a thrust washer is used to preload the inner tubular member against the outer tubular member, then the preload function is achieved, but the thrust washer can break down and cause seizing
Solution Approach 1:
The patent replaces the mechanical thrust washer with a magnetic field-based preload system. Magnets positioned on the inner and outer tubular members create attractive forces that provide consistent preload without contact between the tubular members, eliminating the risk of thrust washer breakdown, shedding, and seizing.
Solution Approach 2:
The magnetic field acts as an intermediary between the inner and outer tubular members, transmitting the preload force without direct mechanical contact. This magnetic mediation eliminates the need for physical thrust washers that can deteriorate and cause reliability issues.
3Ease of manufacture
If dimensional variations in cutting instrument components and hand piece unit are present, then manufacturing is simplified, but the preload force becomes inconsistent
Solution Approach 1:
The magnetic preload system incorporates feedback through the magnetic field interaction between the inner and outer tubular members. The magnetic attraction force automatically compensates for dimensional variations, maintaining consistent preload regardless of manufacturing tolerances in the components or hand piece unit.
Solution Approach 2:
The patent uses magnetic field parameters (strength, polarity, positioning) to control the preload force independently of mechanical dimensional variations. By adjusting magnetic properties rather than relying on precise mechanical fits, consistent preload is achieved despite manufacturing tolerances.
4Device complexity
If the inner tubular member is retained within the outer tubular member without a retention feature, then the design is simplified, but retention problems occur
Solution Approach 1:
The patent replaces mechanical retention features with magnetic retention. Magnets positioned on the tubular members create attractive forces that retain the inner member within the outer member without requiring additional mechanical retention components, achieving both simplicity and reliability.
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 provides a consistent and controlled preload force, reduces the risk of seizing and shedding, and simplifies the design by eliminating the need for thrust washers and compression springs, while allowing for precise control of the preload force, enhancing the reliability and maintenance of surgical cutting instruments.
Implementation Method 1
a force is created between the first magnet and the second magnet when the inner tubular member is slidably disposed within the outer tubular member
Implementation Method 2
the force comprises an attractive force. In another embodiment, the attractive force creates a preload force between the inner tubular member and the outer tubular member
Data Source
AI summary
The present disclosure relates to a cutting tool that includes an outer tubular member having a first magnet and an inner tubular member having a second magnet wherein the inner tubular member is slidably disposed within the outer tubular member. A force, such as an attractive force, is created between the first magnet and the second magnet. The attractive force creates a preload force between the inner tubular member and the outer tubular member. A method of creating a force between an inner and outer tubular member is also disclosed.