Leather Sheet Shaping with Thermoplastic Injection
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Solution Overview
Problem
Current methods for producing moulded outer soles with three-dimensional leather inserts lack a rapid, inexpensive, and safe process to prevent the leather from springing out of shape after cutting and pre-modeling.
Innovation Solution
A process involving a socket punch that compresses the leather sheet against a die, followed by injecting a thin layer of thermoplastic polyurethane to stabilize the shape, forming an indeformable film that adheres to the die's surface profile, ensuring the leather maintains its shape during moulding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a flat leather piece is punched and modelled using conventional techniques, then the insert can be produced with predefined dimensions and profile, but the leather springs out of shape and cannot maintain stability
Solution Approach 1:
The patent applies parameter changes by injecting thermoplastic material that undergoes phase transition from molten state to solid state. The thermoplastic material is injected in molten form to penetrate and bond leather fibers, then cools and solidifies to form a stable matrix that prevents spring-back, thereby changing the physical parameters of the leather insert to achieve shape stability.
Solution Approach 2:
The patent creates a composite material structure by combining leather with thermoplastic material. The thermoplastic material penetrates the leather fibers and bonds them together, forming a composite structure where the thermoplastic acts as a binding matrix that stabilizes the leather insert shape and prevents deformation during subsequent molding processes.
2Manufacturing precision
If multiple separate processes (punching, modeling, stabilizing) are used to produce stable leather inserts, then shape accuracy can be achieved, but production time and complexity increase
Solution Approach 1:
The patent merges multiple separate processes into a single integrated operation. The punching, modeling, and stabilizing functions are combined into one die that performs all operations simultaneously during a single production cycle, eliminating the need for separate modeling and stabilizing steps while maintaining shape accuracy.
Solution Approach 2:
The patent applies preliminary action by incorporating the stabilizing function into the punching operation itself. The thermoplastic material is injected during the punching process to pre-stabilize the leather insert shape, so that when the insert is later placed in the molding die, it already maintains its intended shape without requiring additional stabilization steps.
3Ease of manufacture
If conventional punching and modeling techniques are used without additional stabilizing measures, then production cost is low, but the leather insert cannot maintain its three-dimensional shape
Solution Approach 1:
The patent uses parameter changes by utilizing the phase transition properties of thermoplastic material. The material is injected in molten state to penetrate and bond leather fibers, then cooled to solidify and lock the shape. This phase change approach provides effective shape stabilization at low cost, avoiding the need for expensive alternative stabilization methods.
Solution Approach 2:
The patent introduces thermoplastic material as an intermediary substance that facilitates shape stabilization. The thermoplastic material acts as a mediator between the leather fibers and the final shaped insert, penetrating and bonding the fibers to create a stable composite structure that maintains the three-dimensional shape without requiring complex equipment or processes.
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 solution allows for accurate shaping and prevents spring-back of the leather, enabling stable incorporation of the modelled insert into the moulding process without additional shaping costs or instability issues.
Implementation Method 1
a thin layer of plastic material, such as thermoplastic polyurethane, is injected in one of the two sides of the sheet, which compresses the sheet against the walls of the die or punch
Implementation Method 2
the pre-modelled sheet is forced to perfectly adhere to the wall of the die or punch under the pressure of the injection material
Implementation Method 3
Once it solidifies and cools down, the layer of plastic material forms a surface indeformable film that obstacles spring-back of the modelled leather sheet
Implementation Method 4
Once it solidifies and cools down, the layer of plastic material forms a surface indeformable film
Data Source
AI summary
A process used to cut and model sheets of leather or other modellable materials, according to which cutting and modeling are carried out by means of a die and a lid-punch that cooperate to cut a leather sheet positioned and tightened between the die and the lid-punch according to predefined cutting lines and at the same time model the sheet in a stable way by a plastic film injected on one of the two sides of the sheet.