Needle Shield Laser Welding Plug Shell Assembly
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Solution Overview
Problem
Conventional needle shields face issues with disassembly, adhesion, and particulate formation during assembly, which can lead to needle damage and contamination, and are not suitable for electronic field quality assurance testing due to the lack of an air gap between the plug and shell.
Innovation Solution
A needle shield design featuring a soft plug non-removably bonded to a rigid shell using radiation energy, with a gap between the plug and shell to allow for electronic field testing, and a securing ring to prevent disassembly, reducing insertion and removal forces and preventing particulate formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the plug and shell are mechanically assembled using crimping, then the assembly process is simple, but particulates are formed during assembly which may contaminate the needle shield
Solution Approach 1:
The patent replaces the mechanical crimping system with a laser welding system. The laser welding process joins the plug and shell without mechanical contact that generates particulates, thereby eliminating contamination while maintaining assembly effectiveness.
Solution Approach 2:
The patent changes the joining method from mechanical (crimping) to thermal (laser welding). This parameter change in the joining process eliminates particulate formation while achieving secure attachment of the plug to the shell.
2Reliability
If the plug is injection molded into the shell, then the plug is securely mounted, but no air gap exists between the plug and shell which prevents electronic field testing
Solution Approach 1:
The patent applies local quality by creating a localized air gap between the plug and shell at the testing region, while maintaining secure mounting through laser welding at the bonding interface. This allows electronic field testing to occur through the air gap while the laser weld ensures reliable attachment.
Solution Approach 2:
The patent segments the plug-shell assembly into distinct regions: a bonding region with laser weld for secure mounting and a testing region with air gap for electronic field testing. This segmentation allows both functions to coexist without interference.
3Reliability
If the needle shield is securely mounted to prevent disassembly, then protection is improved, but removal forces become excessively high which may damage the syringe or needle
Solution Approach 1:
The patent replaces mechanical crimping with laser welding to create a controlled bond between the plug and shell. This thermal bonding method provides secure mounting while allowing for controlled removal forces that do not exceed damage thresholds for the syringe or needle.
Solution Approach 2:
The patent changes the bonding mechanism from mechanical interlocking to thermal fusion, which provides reliable attachment while enabling removal forces to be controlled within safe limits, preventing damage to connected components.
4Volume of moving object
If the rigid plastic shell is made thin to reduce size, then the device becomes more compact, but the shell becomes prone to breaking during disassembly
Solution Approach 1:
The patent replaces mechanical crimping with laser welding, which distributes stress more evenly across the shell structure. This allows the use of thinner shell material while maintaining sufficient strength during assembly and removal operations.
Solution Approach 2:
The patent changes the joining method to laser welding, which creates a stronger bond relative to the shell thickness, enabling the use of thinner shell material without compromising structural integrity during disassembly.
5Device complexity
If the plug and shell are mechanically assembled, then disassembly may occur during removal, but alternative secure mounting methods complicate the construction
Solution Approach 1:
The patent replaces complex mechanical assembly methods with laser welding, which provides reliable plug-shell connection stability while maintaining simple construction. The laser welding process creates a direct bond without requiring additional mechanical components or complex assembly steps.
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 design ensures secure mounting of the plug to the shell, prevents needle damage and contamination, and allows for effective electronic field testing while simplifying assembly and reducing removal forces.
Implementation Method 1
The plug is non-removably bonded to the shell in at least a portion of the contact area by at least partially melting a portion of the shell and the plug in the contact area through the application of radiation energy
Implementation Method 2
The plug is laser welded to the shell at a laser weld bond to secure the plug to the shell
Data Source
AI summary
A needle shield is removably mountable to a syringe to protect a user from inadvertent needle pricks and limit contamination of a needle of the syringe. The needle shield includes a plug having an external surface and a shell having an inner surface defining a cavity therein. The plug is positioned within the cavity and a portion of the external surface of the plug is in contact with the inner surface of the shell at a contact area. The plug is non-removably bonded to the shell in the contact area by melting a portion of the shell and the plug in the contact area through application of radiation energy. A securing ring may alternatively be fixed to the shell through the application of radiation energy to secure a shoulder of the plug between the ring and a rib of the shell. The radiation energy is preferably applied by laser welding.