Cross-Country Ski Hot and Cold Bonding Method
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Solution Overview
Problem
Existing methods for producing cross-country skis suffer from thermal stresses due to material-specific thermal expansion, leading to fluctuations in the preload, which is crucial for the running properties, and existing solutions either weaken the cohesion of the composite body or fail to maintain precise preload adjustment.
Innovation Solution
A method involving the hot-bonding of a ski body made from layers with low thermal expansion, using heat-curing adhesives for core layers, and cold-bonding the tread covering and cover layer to minimize thermal stresses, ensuring a stable and precise preload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If all layers are hot-bonded together in a single step, then the bond strength between layers is improved, but thermal stresses cause fluctuations in preload
Solution Approach 1:
The bonding process is divided into two distinct stages: first bonding the core layers (low thermal expansion) together, then separately bonding the tread covering (high thermal expansion) to the core. This segmentation prevents thermal stresses from affecting preload precision while maintaining bond strength through appropriate adhesive selection for each stage.
Solution Approach 2:
The patent changes the bonding temperature parameter between stages: the first bonding stage uses temperatures appropriate for core layer adhesion, while the second stage bonds the tread covering at temperatures that account for its higher thermal expansion coefficient, thereby minimizing thermal stress impact on preload.
2Manufacturing precision
If cold-bonding is used for all layers, then thermal stresses are avoided, but the bond strength is significantly weakened
Solution Approach 1:
The patent changes the temperature parameter from cold-bonding to controlled hot-bonding for the core layers, achieving both sufficient bond strength and acceptable thermal stress levels through optimized temperature selection and adhesive formulation.
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 achieves a stable bond between core layers while avoiding thermal stresses, allowing for precise preload adjustment and maintaining the strength of the composite body, thus enhancing the running properties of cross-country skis.
Implementation Method 1
Heat-curing adhesives are applied to the connecting surfaces between the individual layers of the ski body. The adhesive connections are then made by heating above the curing temperature of the adhesive.
Implementation Method 2
The heating of the layer structure during hot pressing of the composite body can cause thermal stresses, which can be attributed to the material-specific thermal expansion of the individual layers.
Data Source
Figure 1~3
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AI summary
Method for producing a cross-country ski (1), wherein a plurality of layers, in particular a ski core (5), reinforcing layers (4), a cover layer (7) and/or a running-surface coating (3), are adhesively bonded to form a composite body, wherein, in a first step, the ski core (5) and the reinforcing layers (4) are adhesively bonded in the hot state to form a ski body (11), wherein the ski body (11), as reinforcing layers (4), has an upper flange (12) and a lower flange (13), wherein, in a second step, the ski body (11) and at least one further layer (14), in particular the running-surface coating (3), are adhesively bonded to one another in the cold state, and ski (1) which can be produced using said method.