Propeller-Shaped Cutting Shaft for Biological Sample Homogenization
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Solution Overview
Problem
Existing apparatuses for cutting up biological sample material face increased friction issues due to non-positive coupling engagement, leading to difficulties in rotating the shaft at high speeds without slippage, especially when handling solid materials like cattle brain tissue.
Innovation Solution
The apparatus features a shaft that is axially movable and laterally guided, with a positive rotational coupling engagement allowing axial displacement, and a propeller-shaped cutting device that exerts an advancing force, reducing friction by allowing the shaft to rotate without contact with the sample container base.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a non-positive coupling engagement is used to connect the rotary drive device to the shaft, then the coupling structure is simple, but friction increases and slippage occurs during high-speed rotation
Solution Approach 1:
The coupling member is designed to transition from a static pressing force arrangement to a dynamic positive engagement system. During rotation, the propeller-shaped cutting device generates axial thrust that actively pushes the shaft against the stop, creating a dynamic positive coupling engagement that automatically engages during operation rather than relying solely on static pressing force.
Solution Approach 2:
The stop acts as an intermediary element between the shaft and the sample container base. Instead of the shaft directly contacting the base under high pressing force, the stop mediates the interaction by providing a positive engagement surface that the shaft engages against during rotation, distributing forces and reducing direct friction.
2Reliability
If high pressing force is applied to prevent slippage in non-positive coupling, then coupling reliability improves, but friction at the shaft-base contact increases
Solution Approach 1:
The harmful friction contact between the shaft working end and the sample container base is extracted and replaced. Instead of direct contact under high pressing force, the shaft engages with the stop through positive coupling, and the ball bearing extracts the frictional interaction by providing a low-friction support point that does not rely on high pressing force.
Solution Approach 2:
The axial thrust force generated by the propeller-shaped cutting device during rotation is converted from a potential harmful force (that could increase friction) into a beneficial force that presses the shaft against the stop to create positive engagement. The harmful friction is transformed into useful engagement force.
3Stability of the object's composition
If the shaft is fixed in position during rotation, then lateral stability is maintained, but friction and heat generation increase
Solution Approach 1:
The shaft is designed with dynamic positioning capability, allowing controlled axial movement during rotation. The shaft can move axially to engage with the stop for positive coupling while maintaining lateral guidance through the guidance element, transitioning from a static fixed position to a dynamically adjustable position that optimizes both stability and friction reduction.
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 design minimizes friction, enabling efficient cutting of biological samples with reduced risk of slippage and undesirable lateral movement, even with very solid materials, while maintaining effective sample homogenization.
Implementation Method 1
the cutting device is constructed in the shape of a propeller such that it exerts an advancing force in the direction of the coupling end on the shaft, when the shaft rotates in the working direction
Data Source
AI summary
An apparatus for cutting up biological sample material, including a sample container, a rotary drive device separate from the sample container, and a shaft rotatably arranged in the sample container, wherein the shaft has a laterally projecting cutting device in the region of a working end and has a coupling piece in the region of a coupling end, said coupling piece being accessible from outside and being designed for coupling engagement with a coupling counterpart of the rotary drive device, wherein the shaft (14) is arranged with lateral guidance and in an axially displaceable manner in the sample container (10), the coupling piece (19) and the coupling counterpart (21) are designed for producing coupling engagement which is positive-locking in the direction of rotation (23) and permits an axial displacement, and the cutting device (16) is designed in a propeller shape in such a way that, during rotation of the shaft (14) in the working direction, it exerts a propulsive force on the latter in the direction of the coupling end (18).