Seamless Metal Shell Forming for Personal Care Assemblies
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Solution Overview
Problem
The manufacturing of personal care devices with outer metal shells faces challenges in achieving a tight fit and easy mounting of functional components while maintaining strength, rigidity, and ergonomic design, especially when the shell has a complex three-dimensional shape and requires a seamless, one-piece structure.
Innovation Solution
The outer metal shell is formed in a one-piece, homogenous, and seamless structure with annular cross-sections and undercuts, allowing for hydraulic pressure deformation to match the contours of functional components, providing strength, rigidity, and a tight fit, while also accommodating complex shapes and ergonomic needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the outer metal shell is made as a one-piece seamless structure, then strength and rigidity are improved, but manufacturing complexity increases and mounting of functional components becomes difficult
Solution Approach 1:
The patent divides the one-piece metal shell into multiple sections or zones, each with specific geometric features. The shell includes an intermediate section with maximum cross-sectional area and end portions with smaller cross-sectional areas, allowing differential forming approaches while maintaining overall one-piece integrity.
Solution Approach 2:
The patent introduces undercut features that extend in multiple dimensions, creating complex three-dimensional geometries that cannot be formed by simple unidirectional deformation. These undercuts provide mounting access while preserving the one-piece seamless structure.
2Strength
If the outer metal shell has a tight fit with small dimensions, then strength is improved, but mounting of functional components becomes difficult
Solution Approach 1:
The patent incorporates pre-formed undercut features and openings during the hydraulic pressure forming process, before final assembly. These features are created in advance to facilitate subsequent mounting operations, allowing functional components to be accessed and installed without compromising the tight fit of the overall structure.
Solution Approach 2:
The undercut features act as intermediary structures that provide access pathways to the interior mounting space. These undercuts serve as intermediate zones that connect the exterior tight-fitting shell to the interior component mounting area, enabling easy access while maintaining external compactness.
3Shape
If hydraulic pressure is applied to deform the metal shell, then complex shapes can be achieved, but processing equipment complexity increases
Solution Approach 1:
The patent employs hydraulic pressure forming equipment to deform the metal shell blank into complex three-dimensional shapes. The hydraulic system applies controlled pressure to achieve the desired intermediate section with maximum cross-sectional area and end portions with smaller areas, along with undercut features.
Solution Approach 2:
The patent utilizes controlled changes in hydraulic pressure parameters to achieve different deformation stages. By adjusting pressure magnitude and application timing, the process forms complex geometries including undercuts and varied cross-sectional areas in a single integrated forming operation.
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 metal shells with complex shapes, reduces the number of processing steps, and avoids the accumulation of dirt and skin irritation from sharp edges, while maintaining a cool touch and aesthetically pleasing appearance.
Implementation Method 1
forming step for forming the outer metal shell (7, 8) into the desired shape includes hydraulic pressure deforming a metal shell blank (14) to match contours of a 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.