Surgical Sagittal Saw Indexing Head with Low Blade-Slap Coupling
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Solution Overview
Problem
Current surgical sagittal saws with tooless heads generate significant noise due to loose blade fit and require excessive manual force for indexing, and are prone to corrosive bonding issues.
Innovation Solution
A surgical sagittal saw with a rotating indexing head and a coupling assembly that uses ball bearings and a retention assembly to facilitate easy rotation and secure blade placement, minimizing noise and manual effort through a tapered blade slot and retention mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a tooless mechanism with spring loaded device is used for coupling saw blades to the saw head, then blade replacement becomes simple and tool-free, but the blade fit becomes loose causing significant noise generation
Solution Approach 1:
The coupling mechanism is divided into separate functional elements: the tooless release button mechanism for easy blade replacement, and the distinct retention members (clamps or clips) that secure the blade. This segmentation allows independent optimization of each function - the release mechanism remains simple while the retention structure provides tight blade fit to eliminate noise from blade slap against the saw head.
Solution Approach 2:
The patent modifies the physical parameters of the blade-coupling interface by introducing retention members with specific geometric features (clamps, clips, or tensioning elements) that apply controlled force to hold the blade tightly. This changes the contact pressure and fit tightness parameters, ensuring minimal clearance between blade and coupling surfaces to prevent noise-generating movement while preserving easy release capability.
2Adaptability or versatility
If traditional indexing mechanisms are used for rotating the saw head, then the saw can be positioned at different angles, but excessive manual force is required for rotation
Solution Approach 1:
The patent introduces an intermediary mechanism between the user's manual input and the saw head rotation - such as a gear system, cam mechanism, or ratchet-and-pawl assembly. This intermediary translates small manual forces applied to a control element (button, lever, or wheel) into controlled rotational movement of the saw head, reducing the direct force requirement while maintaining positioning versatility through indexed stops.
Solution Approach 2:
The indexing mechanism employs dynamic elements that change their mechanical characteristics during operation - for example, a spring-loaded detent that provides light resistance during rotation but locks firmly at indexed positions, or a cam profile that varies the mechanical advantage throughout the rotation cycle. This dynamic behavior allows easy rotation through most of the range while providing secure positioning at discrete angles.
3Object-generated harmful factors
If tight fit between blade and saw head slot is achieved to minimize noise, then blade slap is reduced, but blade insertion and removal becomes difficult
Solution Approach 1:
The coupling mechanism performs preliminary action by pre-positioning retention members (clamps or clips) in a ready state that automatically engages with the blade upon insertion. The spring-loaded retention members are预先 positioned to apply holding force as soon as the blade enters the coupling slot, ensuring immediate tight fit and noise reduction without requiring additional tightening steps that would complicate removal.
Solution Approach 2:
The patent inverts the traditional coupling approach by using retention members that automatically release when a simple action (pressing a button or lever) is applied. Instead of requiring forceful removal against tight friction fits, the mechanism uses a released state of the retention members that allows easy blade extraction, while maintaining tight holding force during normal operation through the same retention structure.
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 reduces noise generation by ensuring a snug blade fit and minimizes manual force required for indexing, maintaining the saw's functionality while reducing wear and tear.
Implementation Method 1
A first set of ball bearings are disposed between the neck and the collar to facilitate rotation of the neck relative to the collar
Implementation Method 2
a coupling assembly for receiving a saw blade that minimizes the post insertion movement of the blade in the coupling assembly
Data Source
AI summary
A surgical sagittal saw with a head that is able to index, rotate, relative to the longitudinal axis of the saw housing. The head has a neck that extends into an open distal end of the housing. A biasing assembly holds the head and neck sub-assembly in the open distal end of the housing. The biasing assembly is rotatable relative to the housing. A separate lock mechanism selectively holds the head in a fixed orientation around the saw housing longitudinal axis.