Turbine Rotor-Spindle Joint Grooves for Fast-Stopping Medical Cutters
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Solution Overview
Problem
Medical cutting devices with turbine rotors made of stainless steel experience issues with joint failure and poor attachment/detachment of cutting tools due to high inertial moment, leading to heat generation and prolonged rotation stoppages when high-pressure air is stopped.
Innovation Solution
A medical cutting device with a turbine rotor formed from a metal with a density of 4.0 g/cm³ or more and a Young's modulus/density ratio of 20 or more, where the rotor is fixed to a spindle using an adhesive with grooves on both surfaces to enhance the fixing force, and a quick stop mechanism involving seal members to prevent rotor fall-off and rapid rotation cessation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a turbine rotor is formed of stainless steel, then the material strength and durability are improved, but the inertial moment increases causing large load on the joint portion and potential failure
Solution Approach 1:
The joint portion is segmented into multiple engagement surfaces with grooves on both the turbine rotor and spindle. This segmentation distributes the load across multiple contact points rather than a single interface, reducing the stress concentration and preventing joint failure under high inertial loads.
Solution Approach 2:
The joint portion utilizes a composite structure combining the turbine rotor material (stainless steel or other high-density metal) with an adhesive material. This composite approach leverages the high strength of the metal rotor while the adhesive provides additional bonding strength to handle the inertial forces, creating a synergistic joint that withstands the load.
2Strength
If a turbine rotor is formed of stainless steel, then the material strength is improved, but the attachment and detachment of cutting tools becomes poor
Solution Approach 1:
The joint portion is designed with segmented grooves that create distinct engagement zones. This segmentation allows for controlled attachment and detachment points, enabling the cutting tool to be securely fixed during operation while allowing for easy removal when needed, thus improving operational ease without compromising material strength.
3Strength
If a turbine rotor is formed of stainless steel, then the material strength is improved, but heat generation occurs at the joint portion causing failure
Solution Approach 1:
The joint portion is divided into multiple grooved engagement surfaces that distribute the contact area. This segmentation reduces friction concentration at any single point, thereby reducing heat generation during rotation and preventing thermal failure while maintaining the high strength of stainless steel material.
Solution Approach 2:
An adhesive material is introduced as an intermediary between the turbine rotor and spindle at the joint portion. This adhesive layer acts as a mediator that reduces direct metal-to-metal contact and friction, thereby minimizing heat generation while still providing strong mechanical bonding to maintain joint integrity under high-strength material conditions.
4Strength
If a turbine rotor is formed of stainless steel, then the material strength is improved, but the rotation stops slowly after air supply is stopped
Solution Approach 1:
The grooved structure at the joint portion creates multiple engagement points that increase friction during deceleration. This segmented friction distribution provides greater rotational resistance after air supply stops, enabling faster cessation of rotation while the high-strength stainless steel material maintains structural integrity during the deceleration process.
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 solution increases the fixing force of the turbine rotor to the spindle, preventing joint failure and ensuring quick stopping of the rotor and cutting tool after air supply cessation, while maintaining high-speed operation without deformation or noise issues.
Implementation Method 1
the joint portion has grooves in the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle
Data Source
Figure 1
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Figure 3A
AI summary
A medical cutting device including: a rotation portion including a turbine rotor and a spindle, wherein the turbine rotor is formed of a metal having a density of 4.0 [g/cm3] or more and a value of Young's modulus [GPa]/density [g/cm3] of 20 or more, wherein the spindle has a hollow and substantially cylindrical shape and a cutting tool is to be inserted into a hollow interior, wherein the rotation portion has a joint portion where an inner peripheral surface of the turbine rotor is fixed to an outer peripheral surface of the spindle by an adhesive, and wherein the joint portion has grooves in at least one of the inner peripheral surface of the turbine rotor and the outer peripheral surface of the spindle.