Graphite Core Cookware for Even Heat Distribution
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Solution Overview
Problem
Existing multi-layer bonded cookware technologies face challenges in reducing weight and improving thermal characteristics, particularly in achieving efficient heat distribution and conductivity, especially when using solid state bonding techniques.
Innovation Solution
The cookware is constructed with a multi-layer composite structure comprising a graphite core layer between metal layers, where the metal layers are metallurgically bonded using a solid state bonding technique, with dimples on the lower metal layer extending through holes in the graphite core and bonded to an upper metal layer, and the use of pyrolytic graphite for enhanced thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional roll-bonding techniques using aluminum or copper strips are used to bond stainless steel layers, then thermal conductivity is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the bonding method from conventional roll-bonding to solid state bonding, and replaces aluminum/copper strips with a graphite core layer. This parameter change achieves both improved thermal conductivity through graphite's intrinsic properties and simplified manufacturing through the solid state bonding process that directly bonds stainless steel layers without requiring intermediate metal strips
Solution Approach 2:
The patent creates a composite structure with a graphite core layer sandwiched between stainless steel layers. This composite material approach provides the thermal conductivity benefits of graphite while maintaining the corrosion resistance and structural integrity of stainless steel, eliminating the need for separate aluminum or copper bonding layers
2Weight of moving object
If solid state bonding techniques are used to bond metal layers, then weight is reduced, but thermal characteristics and heat distribution need improvement
Solution Approach 1:
The patent employs a composite material structure where a graphite core layer is integrated between stainless steel layers through solid state bonding. Graphite is significantly lighter than aluminum or copper while providing superior thermal conductivity in the plane of the layer, thus reducing overall weight while improving heat distribution across the cookware base
Solution Approach 2:
The patent changes the core layer material from traditional aluminum or copper to graphite, fundamentally altering the thermal and weight parameters. Graphite's layered structure provides excellent in-plane thermal conductivity for even heat distribution while its low density reduces the overall weight of the cookware
3Reliability
If stainless steel is used for the cooking surface to ensure corrosion resistance, then reliability is improved, but thermal conductivity deteriorates
Solution Approach 1:
The patent creates a composite structure with stainless steel outer layers providing corrosion resistance and a graphite core layer providing high thermal conductivity. The stainless steel layers maintain their protective function while the graphite core efficiently distributes heat across the cooking surface, resolving the contradiction between corrosion resistance and thermal performance
Solution Approach 2:
The patent applies different material properties to different parts of the cookware structure: stainless steel is used where corrosion resistance is critical (outer surfaces in contact with food and environment), while graphite is used in the core where thermal conductivity is most important for heat distribution, achieving local optimization of material properties
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
The resulting cookware achieves reduced weight and improved thermal characteristics with even heat distribution, suitable for induction cooking and offering enhanced thermal conductivity and resistance to wear.
Implementation Method 1
the use of pyrolytic graphite for enhanced thermal conductivity
Implementation Method 2
The bonding between layers of these different materials is commonly achieved by conventional roll-bonding techniques... A solid state bonding technique using high static pressure and heat applied over time
Data Source
Figure 1
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AI summary
Provided is cookware made from a bonded multi-layer composite having at least one upper metal layer, a lower metal layer having a plurality of upwardly protruding, spaced-apart dimples formed thereon, and a graphite core layer disposed between the at least one upper metal layer and the lower metal layer. The graphite core layer has a plurality of spaced-apart holes extending through the graphite layer. The plurality of dimples extend through the plurality of holes, and the plurality of dimples are metallurgically bonded to the at least one upper metal layer and an outer portion of the lower metal layer is metallurgically bonded to the at least one upper metal layer. The at least one upper metal layer has a layer of stainless steel or titanium bonded to a sub-layer of aluminum. A method of making the bonded multi-layer composite cookware is also disclosed.