Induction Cooking Vessel Bottom Structure Against Thermal Deformation

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Solution Overview

Problem

Aluminum cooking vessels are not suitable for induction surfaces due to their non-magnetic nature, and when coupled with ferritic stainless steel to enable induction use, they deform excessively upon heating, leading to inefficient thermal transmission and potential loss of contact with cooking surfaces.

Innovation Solution

A vessel design featuring a metal element with recessed parts and seats that allow for thermal expansion clearance, ensuring a stable coupling between the aluminum body and the ferritic stainless steel plate, reducing deformation and maintaining efficient contact with cooking surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a ferritic stainless steel plate is coupled to an aluminum pot bottom to enable induction use, then magnetic compatibility is improved, but bottom deformation increases due to differential thermal expansion

Engineering Contradiction:

Improvemagnetic compatibilityVSAvoidbottom deformation

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The patent applies the thermal expansion principle by designing the aluminum bottom with a convex curvature that anticipates the differential thermal expansion between aluminum and ferritic stainless steel. The pre-formed convex shape compensates for the expansion mismatch that occurs during heating, preventing excessive bottom deformation while maintaining induction compatibility through the coupled steel plate.

Inventive Principle:

Principle #37Thermal expansion

Solution Approach 2:

The patent uses composite materials by coupling ferritic stainless steel plate with aluminum pot bottom. This composite structure combines the magnetic properties of ferritic steel (for induction compatibility) with the lightweight and thermal conductivity properties of aluminum, while the convex design manages the thermal expansion differences between the two materials.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If a ferritic stainless steel plate is coupled to an aluminum pot bottom, then induction compatibility is improved, but contact with cooking surface is lost due to bottom convexity

Engineering Contradiction:

Improveinduction compatibilityVSAvoidcontact with cooking surface

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The convex design of the aluminum bottom pre-compensates for differential thermal expansion between aluminum and ferritic stainless steel. By anticipating the expansion mismatch, the design ensures that the bottom maintains proper contact with the cooking surface even when heated, preventing the reliability issue of losing contact while preserving induction compatibility.

Inventive Principle:

Principle #37Thermal expansion

3Strength

If aluminum penetrates into holes of ferritic stainless steel for joining, then coupling strength is improved, but riveting complexity increases

Engineering Contradiction:

Improvecoupling strengthVSAvoidjoining process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The joining process utilizes the self-service principle by leveraging the natural malleability of aluminum to automatically penetrate and fill the holes in the ferritic stainless steel plate during pressing. The aluminum deformably flows into the holes and rivets itself without requiring separate riveting operations, simplifying the overall joining process while maintaining strong coupling.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent applies parameter changes by utilizing the temperature and pressure conditions during the joining process to alter the physical state of aluminum. Under pressing, the aluminum becomes more malleable and flows into the holes, then upon cooling and pressure release, it solidifies and rivets in place, creating a strong joint without complex procedures.

Inventive Principle:

Principle #35Parameter changes

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 design effectively constrains the aluminum body, minimizing deformation and maintaining efficient thermal transmission and contact with cooking surfaces, even when used on induction or conventional surfaces.

Implementation Method 1

the expansion of the ferritic steel plate/disc due to the heating is about half the expansion of the aluminum given the same thermal conditions

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP2910157B1Vessel for cooking food with anti-deformation bottom

Publication Date: 2018.10.31 BALLARINI PAOLO & FIGLI SPA

Figure 1~2
Figure 3~4
Figure 5

AI summary

A vessel for cooking food on induction or conventional surfaces, comprising a shaped body (2) with a surface that defines a volume for containing the food during cooking, and a metal element (3) arranged on the bottom of the vessel, the metal element (3) defining a support surface (α)for the vessel and having a plurality of parts that are recessed with respect to said support surface (α)in which through holes (F) are made, the recessed parts (4) of the metal element (3) being housed within seats (7) of the shaped body (2), at least one part of said holes (F) having at its interior a mushroom-shaped portion of the shaped body (2), in a manner so as to project from the hole and cover the perimeter thereof, so as to constrain the metal element (3) to the shaped body (2); between the walls of the shaped body (2) which define said seats (7) and said recessed parts (4), and between the walls which define said holes (F) and at least the stalks (14) of said mushrooms (12), a clearance is present.