Seamless Metal Shell Assembly for Personal Care Handles

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Solution Overview

Problem

The challenge lies in manufacturing personal care devices with outer metal shells that offer a tight fit and easy mounting of functional components while maintaining rigidity and ergonomic shape, without compromising the complex three-dimensional design and esthetic appeal, and avoiding sharp edges that can irritate the skin.

Innovation Solution

The solution involves forming a one-piece, homogenous, integral, and seamless outer metal shell with a ring-like or sleeve-like shape and undercuts, which provides superior strength and rigidity, allowing for a tight fit and small size, and is achieved through hydraulic pressure deformation to match the contours of functional components, ensuring ergonomic handling and a smooth surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If openings and perforations are made in the metal shell for inserting functional components, then ease of manufacture and assembly is improved, but sharp and burred edges are created that can irritate skin

Engineering Contradiction:

Improveease of assemblyVSAvoidskin irritation from sharp edges

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful sharp edges created by openings into a beneficial feature by providing protrusions that extend through the openings to cover and protect the sharp edges. The protrusions serve as both functional mounting elements and protective covers, eliminating skin irritation while maintaining ease of assembly.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Strength

If the outer metal shell has a tight fit and small dimensions to accommodate functional components, then strength and rigidity are improved, but ease of manufacture and assembly deteriorates

Engineering Contradiction:

Improvestrength and rigidityVSAvoidease of assembly

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent divides the metal shell into multiple segments or sections, each with specific openings and protrusions designed for particular functional components. This segmentation allows for modular assembly while maintaining overall tight fit and structural strength, making manufacturing and assembly easier without compromising rigidity.

Inventive Principle:

Principle #1Segmentation

3Strength

If the metal shell is formed as a one-piece seamless structure, then strength and esthetic appearance are improved, but manufacturing complexity increases

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent employs hydraulic pressure deformation to form the one-piece seamless metal shell with complex three-dimensional shapes and integrated protrusions. This hydraulic forming process achieves the desired complex geometry in a single operation, maintaining structural strength while avoiding the need for multiple assembly steps or welding operations.

Inventive Principle:

Principle #29Pneumatics and hydraulics

4Manufacturing precision

If hydraulic pressure is applied to deform the metal shell into complex shapes, then manufacturing precision and design flexibility are improved, but processing complexity increases

Engineering Contradiction:

Improveprecision of complex shapesVSAvoidprocessing complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical forming systems with hydraulic pressure deformation to achieve precise complex three-dimensional shapes. The hydraulic system provides controlled, uniform pressure distribution that accurately forms the metal shell geometry, simplifying the overall manufacturing process while maintaining high precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables precise forming of complex shapes with reduced processing steps and eliminates the accumulation of dirt and skin irritation from sharp edges, while maintaining a strong and aesthetically pleasing structure.

Implementation Method 1

forming the outer metal shell includes a hydraulic pressure forming step applying hydraulic pressure onto a side of a metal shell blank positioned in a mold to deform the metal shell blank and press an opposite side of the metal shell blank against the mold to adopt a contour of the mold

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

deform the metal shell blank and press an opposite side of the metal shell blank against the mold to adopt a contour of the mold

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentEP4278926A1Personal care device and method of manufacturing such personal care device

Publication Date: 2023.11.22 BRAUN GMBH

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Figure 3
Figure 4a)~4b)

AI summary

The present invention relates to a personal care device such as an electric hair cutter like shaver or toothbrush, and to a method of manufacturing such personal care device. More particularly, the personal care device comprises a handle and a function head supporting at least one personal care tool, said function head being attached to said handle, wherein at least one of said handle and said function head includes an outer metal shell formed in one piece with an integral, homogeneous, seamless structure having a ring-like or sleeve-like shape with closed annular cross-sections. Said outer metal shell includes at least one undercut portion.