Ophthalmic Instrument Tip Clocking via Laser Welding
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Solution Overview
Problem
Ophthalmic surgical instruments face challenges with inconsistent clocking of beveled tips due to multiple threaded connections, leading to unpredictable tip orientation, and difficulties in defect-free welding of titanium components, which affects sterilization, durability, and manufacturing efficiency.
Innovation Solution
A multi-diameter shaft with a horn and surgical tip assembly featuring a plug with an angle-locating feature, allowing for precise angular positioning and welding, along with a tubular shell and irrigation tube design that facilitates laser welding without additional material, ensuring consistent clocking and defect-free assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple threaded connections are used to support the tip, then the tip can be securely fastened with required preload, but the clocking orientation of the bent/beveled end becomes inconsistent and unpredictable
Solution Approach 1:
The patent replaces the threaded mechanical connection system with a laser-welded mechanical connection system. The tip is laser-welded to the horn, and the horn is laser-welded to the shaft, eliminating threads entirely. This substitution maintains secure fastening through weld strength while providing consistent clocking orientation because the welded connections eliminate the angular variability inherent in threaded assemblies.
Solution Approach 2:
The patent changes the connection method from threaded (angular/rotational) to welded (fixed positional). This parameter change in the connection mechanism transforms the system from one where orientation varies with thread engagement to one where orientation is fixed by the weld geometry, thereby achieving both secure fastening and consistent clocking.
2Strength
If threaded connections are used with preloading, then the tip remains secure during sonic vibration, but the combination of threads, preloads, and tolerance stack-up makes it difficult to predict tip direction
Solution Approach 1:
The patent substitutes threaded connections with laser-welded connections. The welds provide sufficient strength to withstand sonic vibration without requiring preload adjustments. More importantly, the welded connections eliminate the cumulative angular uncertainty from multiple threaded interfaces, making the tip's angular position predictable and consistent.
Solution Approach 2:
The patent extracts and removes the threaded connection elements from the system. By eliminating the threads, the patent removes the source of angular variability caused by thread engagement and preload application, leaving only the welded connections which provide both strength and angular consistency.
3Reliability
If titanium components are welded, then durability and defect-free assembly are achieved, but welding titanium is difficult and requires precise control to avoid defects
Solution Approach 1:
The patent uses laser welding technology to join titanium components. Laser welding provides precise control over the welding process, enabling defect-free assembly of titanium parts while maintaining ease of manufacture through automated, controllable processing.
Solution Approach 2:
The patent applies laser welding parameters (energy density, pulse duration, focal point) to successfully weld titanium components. By optimizing these parameters, the patent achieves defect-free titanium welds while maintaining manufacturing efficiency.
4Manufacturing precision
If press-fit assembly is used to set clocked rotational position, then the bent/beveled end orientation can be controlled, but the connection lacks the strength and robustness of threaded connections
Solution Approach 1:
The patent replaces press-fit connections with laser-welded connections. The welded joints provide both the strength and robustness of traditional threaded connections while maintaining the ability to control clocked orientation through precise positioning during the welding process.
Solution Approach 2:
The patent merges the functions of connection strength and orientation control into a single welded joint. The weld simultaneously provides mechanical strength and fixes the angular position, eliminating the need to choose between press-fit (good orientation, weak connection) and threaded (strong connection, poor orientation control).
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 provides a reliable, durable, and easily sterilizable ophthalmic surgical instrument with consistent tip orientation and defect-free welding, enhancing manufacturing efficiency and reducing manufacturing costs while maintaining high quality and aesthetic standards.
Implementation Method 1
facilitates heating and flowing of the material from the tubular shell into welded bonding contact with the irrigation tube
Implementation Method 2
weld material holding the plug on the shaft in a selected angular and longitudinal position
Implementation Method 3
a horn fixedly threaded into the shaft and that is constructed to provide sonic vibration energy to an end opposite the shaft
Implementation Method 4
the recess is constructed to engage the irrigation tube on the annular flange of the plug when the internal subassembly is assembled into the outer subassembly
Data Source
AI summary
An ophthalmic surgical instrument comprises a multi-diameter shaft, a horn fixedly threaded into the shaft, a surgical tip for ophthalmic surgery including a tip end and threadably engaging the horn opposite the shaft, and a plug on the shaft. Weld material holds the plug on the shaft in a selected angular and longitudinal position with an angle-locating recess on the plug's circumference having a predetermined angular clocked relation to a face direction of the tip end. The plug's recess engages an irrigation tube on a subassembled handle with shell and irrigation tube, such that the subassembled handle has a known clocked position relative to the tip end of the tip, thus facilitating use by a surgeon. A related method is also disclosed and claimed.