Flexible Tube Die Segmentation for Short Soft Tip Control
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Solution Overview
Problem
Existing flexible tube production apparatuses face difficulties in producing a short soft tip portion at the front end of catheters, as the switching valve mechanism leads to residual resin being extruded along with the soft tip resin, resulting in an elongated soft tip length.
Innovation Solution
A flexible tube production apparatus with multiple extruders and a die system that includes switchable valves and supply passages, allowing for precise control of resin flow to minimize the length of the soft tip by efficiently switching between different resin extrusions and ensuring minimal residual resin is extruded with the soft tip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a switching valve mechanism is used to switch between resin for continuous hardness change and resin for soft tip, then the soft tip can be formed by inline extrusion molding, but residual resin in the flow passage causes the soft tip length to become long
Solution Approach 1:
The die flow passage is segmented into multiple sections: a first flow passage for receiving resin during continuous hardness change extrusion, and a second flow passage for receiving resin during soft tip extrusion. This segmentation allows independent control of resin flow paths, enabling complete discharge of residual resin from the first passage before soft tip resin is supplied, thus achieving short soft tip length while maintaining inline extrusion molding capability
Solution Approach 2:
Before switching to supply resin for the soft tip, the system performs a preliminary action of completely discharging the resin currently present in the first flow passage. This is achieved by switching the switching valve to discharge mode, which empties the residual resin that would otherwise contaminate the soft tip portion, thereby enabling precise control of soft tip length
2Manufacturing precision
If residual resin is discharged before soft tip resin supply, then soft tip length can be controlled, but production time increases due to additional discharge step
Solution Approach 1:
The system maintains continuous useful action by overlapping the resin discharge process with the preparation for next resin supply. The switching valve transitions smoothly between discharge and supply modes without idle time, and the resin discharge occurs during the natural transition phase between different extrusion stages, eliminating additional waiting time and maintaining high production efficiency while achieving precise soft tip length 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
Enables the continuous extrusion molding of a resin layer with varying hardness and a short soft tip, improving the flexibility and operational ease of catheters by reducing the length of the soft tip portion.
Implementation Method 1
a first extruder (1) that extrudes a first resin, a second extruder (2) that extrudes a second resin
Data Source
AI summary
A die has an inner die that has a straight portion of circular columnar outer shape and a convergent tapered portion provided closer to an extrusion port side than the straight portion and an outer die that houses the inner die. A first supply passage connecting a first valve and a flow passage, a second supply passage connecting a second valve and the flow passage, and a third supply passage connecting a third valve and the flow passage are provided inside the die. Downstream side end portions of the first supply passage and the second supply passage are connected to a portion of the flow passage formed between the straight portion and the outer die and a downstream side end portion of the third supply passage is connected to a portion of the flow passage formed between the tapered portion and the outer die.