Multi-Layer Cookware with Dimpled Bonding to Prevent Hot Spots
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Solution Overview
Problem
Existing multi-layer composite cookware experiences hot spots due to high thermal conductivity materials like aluminum and copper, leading to food sticking and premature degradation of non-stick coatings, and conventional manufacturing methods result in significant scrap losses.
Innovation Solution
A multi-layer composite cookware construction with a stainless steel cook surface featuring raised dimpled portions, formed by selectively bonding stainless steel, aluminum, and another stainless steel layer using pressure and temperature, which reduces thermal conductivity in the dimpled areas to prevent hot spots and minimizes scrap through a diffusion bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high thermal conductivity materials like aluminum and copper are used in multi-layer composite cookware, then heating speed is improved, but hot spots occur on the cooking surface causing food sticking and premature degradation of non-stick coatings
Solution Approach 1:
The patent applies local quality by creating a multi-layer composite structure where different materials are strategically positioned: a stainless steel layer with raised dimpled portions provides localized thermal management, an aluminum or copper layer provides high thermal conductivity in specific zones, and a PTFE non-stick coating protects the cooking surface. This localized material distribution allows different regions of the cookware to have different thermal properties, preventing hot spots while maintaining fast heating.
Solution Approach 2:
The patent employs composite materials by bonding together stainless steel, aluminum/copper, and PTFE in a multi-layer construction. The stainless steel layer with dimpled portions bonded to the high-conductivity aluminum or copper layer creates a composite structure that combines the corrosion resistance and thermal management of stainless steel with the high thermal conductivity of aluminum or copper, eliminating hot spots while maintaining fast heating performance.
2Ease of operation
If PTFE non-stick coating is applied to the cooking surface, then food sticking is prevented, but the coating degrades prematurely due to localized hot spots
Solution Approach 1:
The stainless steel layer with raised dimpled portions provides localized thermal management that protects the PTFE coating in critical areas. The dimpled structure creates thermal barriers that prevent excessive heat from reaching the PTFE coating, thereby extending its service life while maintaining non-stick performance.
Solution Approach 2:
The stainless steel layer with raised dimpled portions acts as a protective barrier that cushions the PTFE coating from thermal degradation before it occurs. This protective layer prevents hot spots from directly affecting the PTFE, thereby extending its useful life.
3Ease of manufacture
If conventional manufacturing methods are used for multi-layer composite cookware, then production is simplified, but significant scrap losses occur
Solution Approach 1:
The raised dimpled portions are formed in the stainless steel layer before the bonding process. This preliminary formation of the dimpled structure allows for near-net-shape manufacturing, minimizing the need for subsequent machining or material removal and thereby reducing scrap losses.
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 cookware heats uniformly, reducing sticking issues and extending the life of non-stick coatings, while the diffusion bonding method minimizes scrap losses and allows for near-net shape manufacturing with minimal waste.
Implementation Method 1
the aluminum layer 4 thermally expands, forcing the first stainless steel layer 2 to expand into the through holes 14 of the perforated template 10 to form a plurality of dimples or bubbles 20
Implementation Method 2
solid state bonding between the layers of materials occurs
Implementation Method 3
a greater amount of thermal energy from the heat of the cooking range or the like is transmitted by conduction through the flat surfaces compared with the thermal energy conducted through the raised bubbles
Data Source
Figure 1~2B
Figure 3
Figure 4
AI summary
Cookware comprising a selectively bonded composite of at least two layers of materials wherein the first of the at least two layers of materials has a plurality of spaced-apart bubbles formed on its surface, defining a cooking surface of the cookware, and a second layer of two layers of material is bonded thereto, wherein the bonding between the bubbles and the second material is of a lesser degree than the bonding between the first and second layers of materials in areas intermediate the bubbles, whereby a coefficient of heat conductivity is greater in the intermediate areas than in the bubbles.