Articulated Endoscope Bending Section Moulding Without Weak Hinge Welds
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Solution Overview
Problem
The manufacture of integrally moulded one-piece bending section bodies for endoscopes is challenging due to small size, complex structure, and the formation of welding zones that reduce mechanical strength, particularly at hinge members.
Innovation Solution
A method and mould design with separable parts forming sub-cavities, allowing controlled injection of plastic material to avoid welding zones at critical areas by ensuring that each cavity is separated by an odd number of cavities without external fluid inlets, promoting fusion within the segment bulk rather than at hinge members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If multiple injection points are used to mould the bending section body, then the manufacturing process becomes feasible, but welding zones are formed that reduce mechanical strength at hinge members
Solution Approach 1:
The mould cavity is segmented into multiple sub-cavities corresponding to different segments of the bending section body. Each sub-cavity can be independently controlled for material injection, allowing the process to be divided into manageable zones that reduce unwanted welding at critical hinge locations.
Solution Approach 2:
Different regions of the bending section body are treated differently during injection. The hinge member regions are designed to avoid welding zones by controlling material flow, while other regions can accommodate necessary welding. This creates local quality variations in the material structure optimized for each region's functional requirements.
2Manufacturing precision
If material flows from multiple injection points, then complete coverage of the mould cavity is achieved, but welding zones form where flows meet reducing structural integrity
Solution Approach 1:
The mould design pre-establishes flow paths and injection sequencing that guide material flow to meet at predetermined locations away from hinge members. By planning the injection sequence and cavity pressure distribution in advance, the harmful welding zones are directed to non-critical areas before the moulding process begins.
3Ease of operation
If the bending section body is made small and highly flexible, then maneuverability in the body cavity is improved, but the structure becomes more susceptible to failure at hinge members
Solution Approach 1:
The hinge members utilize thin film structures that provide the necessary flexibility for the bending section to navigate tortuous paths in the body cavity. However, the injection moulding process is specifically designed to avoid creating welding zones in these thin film hinge regions, preserving their structural integrity while maintaining flexibility.
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 approach results in an elongate articulated bending section body with improved mechanical strength and reduced risk of failure at hinge members, ensuring robustness under operational forces.
Implementation Method 1
injecting said liquified plastic material into said first number of sub-cavities via the external fluid inlets and into the odd number of sub-cavities via said first number of sub-cavities only, allowing the liquified plastic material to set to form said elongate articulated bending section body
Data Source
AI summary
A method for moulding an elongate articulated bending section body (4) for a medical device including a number of segments (7) interconnected via a number of hinge members (8). The method includes the use of a mould having a first number of sub-cavities where each of the sub-cavities has at least one external fluid inlet through which a liquified plastic material is injected into the mould. The sub-cavities are so distributed that each sub-cavity is separated from another sub-cavity by an odd number of sub-cavities without an external fluid inlet.