Flexible Mold Core for Degradable Stent Injection Molding

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Solution Overview

Problem

The existing injection molding process for degradable intravascular stents faces challenges such as difficulty in demolding, deformation, and damage due to heat expansion and cold contraction, leading to structural inaccuracies.

Innovation Solution

An injection molding method using a flexible mold core structure, where a metal rod is wound with a flexible metal film, applying inward bending stress, and assembled with a mold sleeve for injection molding, allowing for easy separation and reuse, while preventing deformation through inward curling of the metal film after demolding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an integrated mold structure is used for injection molding, then the manufacturing process is simple, but the stent is tightly bonded to the mold and difficult to demold, causing damage and fracture

Engineering Contradiction:

Improvemold structure simplicityVSAvoiddemolding difficulty

Core Design Contradiction:

Ease of manufactureVSEase of operation

Solution Approach 1:

The mold structure is divided into multiple independent components: a mold body and a separate flexible mold core. The flexible mold core can be detached from the mold body after injection molding, allowing the stent to be easily removed without damaging the stent or requiring complex demolding operations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The mold core is designed with flexible characteristics, allowing it to dynamically adjust its shape and size. This flexibility enables the mold core to expand during injection molding to form the stent, then contract after demolding to facilitate easy separation from the stent without causing damage.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If the stent is demolded before temperature decreases in an integrated mold design, then the demolding process is straightforward, but the stent suffers serious deformation due to heat expansion and cold contraction

Engineering Contradiction:

Improvedemolding process simplicityVSAvoidstent dimensional accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The flexible mold core is designed to automatically contract to a smaller size after the injection molding process. This preliminary contraction action creates clearance between the mold core and the stent, enabling easy demolding before the stent cools down, thus avoiding deformation caused by thermal contraction while maintaining dimensional accuracy.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If a flexible mold core structure is used with detachable components, then demolding becomes easy and deformation is reduced, but the device complexity increases

Engineering Contradiction:

Improvedemolding easeVSAvoidmold structure complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The mold core is constructed using flexible materials that can elastically deform. This flexibility allows the mold core to be inserted into and removed from the mold body without complex mechanical linkages or actuation mechanisms, simplifying the overall structure while still achieving easy demolding and reduced deformation.

Inventive Principle:

Principle #30Flexible shells and thin films

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 method facilitates easy demolding, reduces damage, and maintains structural integrity by preventing heat-induced deformation, enabling the production of stents with various shapes and micro-structures, and allows for reusability of the mold components.

Implementation Method 1

after the metal rod is removed, the flexible metal film will curl inwards

Methodology Applied

Scientific EffectElastic recovery: Elastic Recovery

Implementation Method 2

performing injection molding processing of the degradable intravascular stent

Methodology Applied

Scientific EffectInjection molding:

Implementation Method 3

the stent is prone to serious deformation due to the influence of heat expansion and cold contraction after demolding

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11712820B2Injection molding method for degradable intravascular stent with flexible mold core structure

Publication Date: 2023.08.01 BEIJING INST OF TECH

AI summary

Disclosed is an injection molding method for a degradable intravascular stent with a flexible mold core structure. The injection molding method includes the following steps: Step 1, winding a metal rod with a flexible metal film, and applying an inward bending stress to the flexible metal film; Step 2, fixing the flexible metal film to the metal rod, and processing a complementary structure of the degradable intravascular stent on the surface of the flexible metal film; Step 3, performing injection molding processing; Step 4, ending the injection molding, removing the mating body of the flexible metal film and the metal rod and the degradable intravascular stent formed on the surface of the flexible metal film by injection molding, performing cooling, separating the metal rod from the flexible metal film, withdrawing the metal rod, and then removing the flexible metal film to obtain a formed degradable intravascular stent.