Co-Injection Shoe Sole Manufacturing with Supercritical Foaming
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Solution Overview
Problem
Conventional footwear manufacturing techniques require separate molding steps for each component of the sole structure, leading to increased costs, complexity, and cycle time, as well as limitations in material composition due to the need for adhesives and restricted movement of components.
Innovation Solution
A method involving co-injection of materials into a single mold using separate injection lines with plasticization, mixing, and injection zones, where supercritical fluids are used to foam the materials, allowing for the formation of a sole structure with a midsole and outsole in a single step, potentially embedding a plate within the sole structure without traditional bonding methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional separate molding steps are used for each sole component, then each component can be formed with specific material properties, but manufacturing time and process complexity increase
Solution Approach 1:
The patent combines multiple separate molding operations into a single co-injection molding process where midsole and outsole materials are injected simultaneously through separate injection lines into a shared mold cavity, eliminating sequential processing steps and reducing manufacturing cycle time
2Ease of manufacture
If conventional separate molding steps with adhesives are used, then components can be formed independently, but the need for bonding increases process complexity and cost
Solution Approach 1:
The invention merges the formation of multiple sole components into a single integrated molding process where midsole and outsole are co-injected and bonded together through direct material bonding during injection, eliminating the need for separate adhesive application and bonding operations
Solution Approach 2:
The patent replaces mechanical/chemical bonding systems (adhesives, stitching, overmolding) with a direct material bonding mechanism that occurs during the co-injection process itself, where the injected materials bond together through the injection process without requiring additional bonding agents or operations
3Ease of manufacture
If adhesives are used to bond sole components, then components can be assembled, but material composition options are limited
Solution Approach 1:
The invention substitutes adhesive-based assembly with direct material bonding through co-injection, allowing a broader range of material combinations including thermoplastics, thermoplastic elastomers, and other materials that would not be compatible with adhesive bonding, thereby expanding material composition versatility
4Manufacturing precision
If conventional separate molding processes are used, then each component can be optimized individually, but the number of machines and operations increases
Solution Approach 1:
The patent consolidates multiple separate molding machines and operations into a single co-injection molding system with multiple injection lines feeding into one mold cavity, reducing the total number of machines while maintaining the ability to optimize each component's material properties through dedicated injection parameters
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 reduces manufacturing time and costs, eliminates the need for adhesives, and expands material composition options while ensuring secure component integration and improved component properties.
Implementation Method 1
The first blowing agent can be a supercritical fluid within the first mixing zone
Implementation Method 2
The first blowing agent can nucleate within the mold to expand and foam the first material within the mold
Implementation Method 3
The first blowing agent can nucleate within the mold to expand and foam the first material within the mold
Data Source
AI summary
A method of manufacturing a sole structure includes melting a first material in a first plasticization zone of a first injection line and melting a second material in a second plasticization zone of a second injection line. A first blowing agent is injected into the first material within a first mixing zone of the first injection line. The first blowing agent is a supercritical fluid within the first mixing zone. The first material and the second material are co-injected into a mold to form the sole structure. The first material is injected from a first injection chamber and the second material is injected from a second injection chamber. The first blowing agent nucleates within the mold to expand and foam the first material within the mold.