Ski Boot Sole Overmolding Eliminates Glue
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Solution Overview
Problem
The production of ski-mountaineering boots is costly due to the chemical inconsistency between elastomeric materials used for the sole and plastic materials used for the rigid casing, requiring expensive chemical catalysts and special glues for attachment.
Innovation Solution
The method involves using a thermoplastic material with a higher melting temperature to over-inject the rigid casing directly onto a thermoplastic polyurethane sole, eliminating the need for glues and simplifying the production process by fixing a metal rigid front insert onto the sole before injection molding, allowing for a stable and unmovable joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If elastomeric material is used for the sole and plastic material for the rigid casing, then the sole provides high friction for gripping snow and ice, but the chemical inconsistency between materials requires expensive chemical catalysts and special glues for attachment
Solution Approach 1:
The patent merges the sole and rigid casing into a single integrated component made entirely of thermoplastic material. The sole is molded as one piece with the rigid casing through overmolding, eliminating the need for separate attachment processes and expensive chemical catalysts while maintaining the high friction surface needed for gripping snow and ice.
Solution Approach 2:
The patent changes the material parameter from chemically inconsistent elastomeric-plastic combination to a consistent thermoplastic material throughout. This parameter change allows the use of standard thermoplastic bonding processes instead of expensive chemical catalysts and special glues, significantly reducing manufacturing costs while maintaining functional performance.
2Strength
If expensive chemical catalysts and special glues are used to attach the sole to the rigid casing, then the attachment is strong, but the production costs increase significantly
Solution Approach 1:
The patent combines the sole and rigid casing into a single molded part, eliminating the need for separate bonding materials such as expensive chemical catalysts and special glues. The integration is achieved through overmolding where thermoplastic material is molded directly over the sole, creating a strong mechanical bond without additional material costs.
Solution Approach 2:
The patent uses the sole itself as the mold surface for creating the rigid casing. The mold cavity is designed to copy the sole's geometry, allowing the rigid casing to be formed directly over the sole in a single molding operation, eliminating the need for separate attachment materials and reducing production costs.
3Ease of manufacture
If the sole is attached to the rigid casing using gluing, then the attachment is achieved, but the process is relatively long and laborious
Solution Approach 1:
The patent merges the sole attachment process into the rigid casing molding process itself. Through overmolding, the thermoplastic material is molded directly over the sole in a single continuous operation, eliminating separate gluing steps and significantly reducing production time and labor requirements.
Solution Approach 2:
The patent performs preliminary positioning of the sole within the mold cavity before the rigid casing material is injected. The sole is pre-placed and secured in the correct position, allowing the thermoplastic material to flow over it and bond automatically during the molding process, eliminating the need for subsequent attachment operations.
4Strength
If a metal rigid front insert is fixed onto the sole before injection molding, then a stable and unmovable joint is achieved, but an additional fixing step is required
Solution Approach 1:
The patent performs preliminary fixation of the metal rigid front insert onto the sole before the injection molding process. The insert is secured in the correct position on the sole, and then the thermoplastic material is molded over both components, automatically encapsulating and bonding the insert to the sole-casing assembly in a single subsequent molding operation.
Solution Approach 2:
The patent combines multiple components (metal insert, sole, and rigid casing) into a single integrated assembly through overmolding. The thermoplastic material bonds all three components together in one process step, creating a stable and unmovable joint while maintaining relative simplicity in the manufacturing process.
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 production costs and time by eliminating the need for glues and simplifying the manufacturing process, while ensuring a strong and durable bond between the sole and the rigid casing.
Implementation Method 1
injecting a second thermoplastic material inside the closed cavity (101) that already accommodates the sole (10), so that such first thermoplastic material can overlap the sole (10) and, at the same time, fill the remaining empty space
Implementation Method 2
The production method of ski boot (1) comprises, in sequence, the steps of: separately realizing the sole (10) of shell (2) in a first thermoplastic material; inserting the sole (10) inside a mold (100) for the injection molding of plastic material
Data Source
Figure 1~2
Figure 3~6
Figure 7~9
AI summary
A production method of a ski-boot (1) comprising a substantially shoe-shaped rigid shell (2) adapted to accommodate the foot of the user, and which comprises: a rigid casing (9) shaped so as to accommodate and enclose the foot of the user, and a sole (10) which is arranged to cover the bottom wall (9b) of the rigid casing (9); the production method of the ski-boot (1) comprising the steps of realizing, by means of an injection molding process, at least the front plate-like portion (10, 20a) of the sole (10) of the rigid shell (2); inserting the front plate-like portion (10, 20a) of the sole (10) inside a mold (100, 200) for the injection molding of plastic material, which is internally provided with a closed cavity (101, 201) that substantially copies in negative the shape of the rigid shell (2) to be realized; injecting a thermoplastic material inside the closed cavity (101, 201) that already accommodates the front plate-like portion (10, 20a) of the sole (10), so that the plastic material can overlap the front plate-like portion (10, 20a) and, at the same time, fill the remaining empty space, thus to form the rigid casing (9) of the rigid shell (2); and finally extracting the resulting piece from the mold(100).