Spring-Locked Assembly Nest for Precise Pen Injector Positioning
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Solution Overview
Problem
The challenge in the manufacturing of drug delivery devices is to securely and automatically assemble sub-assemblies, such as cartridges and housings, on an assembly line, requiring a precise and stable orientation and locking mechanism to maintain the sub-assemblies in predetermined positions during the assembly process.
Innovation Solution
An assembly nest with a locking mechanism that includes a resilient member, such as a coil spring, to move between unlocked and locked positions, ensuring the sub-assemblies are securely held in place using locking pins, arms, or clamping mechanisms, allowing for precise orientation and retention of tubular sub-assemblies on an automated production line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking mechanism is added to secure sub-assemblies in predetermined positions, then the reliability and positioning precision are improved, but the device complexity increases
Solution Approach 1:
The locking mechanism utilizes the insertion motion itself to trigger the locking action. As the sub-assembly is inserted into the nest, the movement automatically actuates the locking pin or resilient arm to engage with the sub-assembly, making the system self-locking without requiring external actuators or complex control systems.
Solution Approach 2:
The patent replaces complex actuated locking systems with simple passive mechanical elements such as spring-loaded resilient arms or gravity-assisted locking pins. These elements rely on basic mechanical principles (elasticity, gravity) rather than powered actuators, reducing overall system complexity while maintaining reliable locking functionality.
2Reliability
If a locking mechanism with actuation is used to change locking position, then the reliability is improved, but the ease of operation and device complexity worsen
Solution Approach 1:
The locking mechanism automatically engages during the normal insertion process of the sub-assembly into the nest. The actuation force is derived from the insertion motion itself, eliminating the need for separate locking operations. This self-service approach simplifies operation while ensuring reliable locking.
Solution Approach 2:
The locking action is performed preliminarily during the insertion phase, before the assembly process begins. By locking the sub-assembly in place during insertion, the system eliminates the need for subsequent locking operations, simplifying the overall workflow and improving ease of operation.
3Manufacturing precision
If multiple locking points are used to prevent axial and non-axial movement, then the positioning precision is improved, but the device complexity increases
Solution Approach 1:
The locking function is segmented into multiple independent simple elements (e.g., radial locking pins and axial resilient arms) that work together. Each element handles a specific direction of constraint, and their combined effect provides multi-directional positioning precision without requiring a single complex locking structure.
Solution Approach 2:
The locking mechanism is designed with multi-functional elements that simultaneously constrain multiple degrees of freedom. For example, a single resilient arm structure can provide both radial positioning and axial positioning, eliminating the need for separate locking mechanisms for each direction and reducing overall structural complexity.
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 assembly nest effectively secures sub-assemblies in predetermined positions, preventing axial and non-axial movement, enabling efficient assembly and movement along the production line while simplifying the construction by eliminating the need for actuation to change the locking mechanism's position.
Implementation Method 1
The resilient member is a coil spring arranged about the pin and arranged to urge the gripping end against a sub assembly mounted to the base
Data Source
AI summary
An assembly nest for transporting a tubular sub assembly of a drug delivery device on an automated production line, in which the tubular sub assembly includes a tubular body and a cap that is wider than the tubular body. The assembly nest includes a base against which a sub assembly of a drug delivery device is mountable to orientate said sub assembly in a predetermined position; and locking mechanism having a resilient member to urge the locking mechanism into one of: an unlocked position, in which a sub assembly of a drug delivery device can be mounted to the base; or a locked position, in which the locking mechanism engages a mounted sub assembly to retain it in its predetermined position on the base.