Light Safety Shoe Weight Reduction via Composite Sole Injection
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Solution Overview
Problem
Existing safety shoes are excessively heavy due to the use of dense materials for durability and safety features, leading to discomfort during prolonged wear.
Innovation Solution
The safety shoe is designed with a lightweight sole made of polyester-based polyurethane, an expanded polyethylene-based functional insert, and a non-woven anti-puncture sheet, combined with a safety toecap, to achieve reduced weight and maintain durability and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dense materials are used for sole and safety components, then safety and durability are improved, but weight increases significantly
Solution Approach 1:
The patent employs composite materials throughout the shoe construction: the upper combines breathable mesh with synthetic overlays, the midsole uses EVA foam with polyurethane layers, and the outsole combines rubber with thermoplastic polyurethane. This multi-material composite approach optimizes the weight-strength-durability balance by selecting materials with specific properties for each functional zone, reducing overall weight while maintaining safety and durability standards.
Solution Approach 2:
The patent applies local quality by providing enhanced protection only where needed: a safety toe cap is placed specifically at the toe region, an anti-puncture sheet is positioned at the heel area, and reinforced synthetic overlays are applied at high-wear zones. This localized approach to safety features avoids the need for uniformly dense materials throughout the entire shoe, significantly reducing weight while maintaining required safety standards.
2Ease of manufacture
If traditional bonding methods are used to attach sole to upper, then manufacturing is simpler, but durability and performance are reduced
Solution Approach 1:
The patent replaces the traditional mechanical bonding system (adhesives and stitching) with a direct injection molding process. The thermoplastic polyurethane outsole is molded directly onto the upper assembly, creating a permanent mechanical interlock through material fusion. This substitution eliminates bonding weaknesses while maintaining manufacturing efficiency, achieving both durability and ease of manufacture.
3Strength
If heavy materials are used to ensure resistance to abrasion and damage, then protection is improved, but user comfort during prolonged wear deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully selecting material densities and thicknesses to optimize the strength-comfort balance. The midsole uses EVA foam with specific density ranges to provide cushioning, while the outsole uses thermoplastic polyurethane with controlled thickness to deliver abrasion resistance without excessive weight. The safety toe cap and anti-puncture sheet are positioned and sized to provide minimum required protection with minimal weight addition, significantly improving user comfort during prolonged wear.
Data Source
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AI summary
The present invention relates to a light safety shoe (1), comprising: - an upper ( 2 ); a sole (3) made by means of injection molding directly onto said upper (2); a safety toecap (4) placed at the toe of the shoe (1); - a anti -puncture sheet (9) housed in said sole (3); - a functional insert (7) placed within said sole (3), below said anti-puncture sheet (9). According to the invention, the light safety shoe (1) has, with reference to a European size 42, a weight lower or equal to 400 grams.