Seamless Metal Shell Forming for Compact Personal Care Handles
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Solution Overview
Problem
Existing personal care devices with metal shells face challenges in manufacturing complex shapes with a tight fit and ergonomic design while avoiding skin irritation from sharp edges, and require numerous processing steps with expensive tools.
Innovation Solution
A personal care device with a one-piece, integral metal shell having undercuts and hydraulic pressure-formed structure, incorporating plastic chassis members to cover edges and facilitate easy mounting of functional components, ensuring a seamless and strong outer shell with a cool touch feel and reduced skin irritation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the outer metal shell has a tight fit and small dimensions to accommodate functional components, then the device achieves a compact size and strong structure, but it becomes difficult to manufacture the metal shell precisely and difficult to assemble the functional components
Solution Approach 1:
The device is divided into modular functional components (motor unit, battery, control electronics, display) that can be manufactured separately and then assembled into the metal shell. This segmentation allows each component to be optimized and manufactured independently, reducing the overall manufacturing difficulty while maintaining a compact integrated device.
Solution Approach 2:
Functional components are nested within the metal shell structure, with smaller components housed within larger ones. The motor unit, battery, and electronics are arranged in a nested configuration that maximizes space utilization while maintaining easy access for assembly and maintenance.
2Volume of moving object
If the outer metal shell has a tight fit and small dimensions, then the device achieves a compact size, but the edges of openings and perforations become sharp and burred causing skin irritation
Solution Approach 1:
The metal shell is designed with pre-formed rounded edges and recesses at all openings and perforations before assembly. This preliminary design feature prevents sharp edges from contacting the user's skin, eliminating the harmful effect of skin irritation before it can occur during device use.
Solution Approach 2:
The metal shell exhibits different local qualities: smooth rounded edges at user-contact areas versus precise sharp edges at functional openings for component insertion. This localized differentiation allows the shell to maintain structural integrity and manufacturing precision while providing skin-safe surfaces where needed.
3Shape
If numerous processing steps with expensive tools are used to manufacture the metal shell, then complex shapes with tight fit can be achieved, but the manufacturing process becomes complicated and costly
Solution Approach 1:
Hydraulic pressure forming is used to create complex three-dimensional shapes in the metal shell and functional components. This hydraulic forming process achieves precise complex geometries with tight tolerances in a single step, eliminating the need for multiple sequential processing operations and reducing both manufacturing complexity and cost.
Solution Approach 2:
The manufacturing process utilizes parameter changes in material properties during forming, where the metal is subjected to controlled hydraulic pressure and temperature conditions to achieve the desired complex shape. This allows complex geometries to be formed directly from blank material without requiring numerous intermediate machining steps.
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 solution allows for precise formation of complex shapes with a tight fit and small footprint, enhancing ergonomic handling and aesthetic appeal while minimizing processing steps and skin irritation risks.
Implementation Method 1
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 said mold to adopt a contour of the mold
Data Source
Figure 1~2
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 which is formed with 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 said mold to adopt a contour of the mold.