Tolerance-Compensating Coupling Section for Personal-Care Implements
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Solution Overview
Problem
Mass production of multi-component personal-care implements, such as electric toothbrushes, faces challenges in maintaining uniformity and precision due to factors like mold shrinkage and deformation during assembly, leading to strict tolerance requirements that are difficult to achieve across different manufacturing locations and conditions.
Innovation Solution
A coupling section with a tolerance-compensation element, including a drive shaft and a bushing with a through-hole, allows for adjustable positioning and alignment, enabling longitudinal, lateral, and angular adjustments to compensate for variations in parts, thereby relaxing strict tolerances and simplifying the assembly process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If strict tolerances are applied to ensure uniformity and precision of multi-component parts, then manufacturing precision is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by modifying the tolerance parameters of the coupling section components. Instead of maintaining strict tolerances across all components, the invention allows for relaxed tolerances in the coupling section while maintaining overall assembly precision through the tolerance compensation mechanism.
Solution Approach 2:
The coupling section acts as an intermediary element between the handle and attachment tool. It mediates the tolerance variations by providing a interface that can accommodate dimensional variations in the components it connects, thereby simplifying the overall assembly process while maintaining precision.
2Manufacturing precision
If strict tolerances are enforced across all components, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The invention changes the tolerance parameters for the coupling section components, allowing for broader acceptable ranges in dimensional accuracy. This makes mass production easier while maintaining overall assembly precision through the tolerance compensation capability of the coupling section.
Solution Approach 2:
The coupling section is segmented into distinct components (first coupling component and second coupling component) that can be manufactured separately with relaxed tolerances. This segmentation allows each component to be produced more easily while the assembly provides overall precision through their coordinated interaction.
3Reliability
If tight tolerances are maintained for all parts, then reliability of assembly is improved, but productivity decreases
Solution Approach 1:
By changing the tolerance parameters to be more relaxed for the coupling section components, the manufacturing process becomes faster and more productive. The coupling section compensates for these relaxed parameters, maintaining assembly reliability without sacrificing production speed.
Solution Approach 2:
The coupling section provides self-service by automatically compensating for tolerance variations in the components it connects. This self-compensation mechanism maintains assembly reliability without requiring additional precision-control measures that would slow down production.
4Ease of manufacture
If tolerance compensation mechanisms are added to relax tolerances, then ease of manufacture is improved, but device complexity increases
Solution Approach 1:
The coupling section is divided into separate components (first and second coupling components) with specific features. This segmentation provides the tolerance compensation functionality while keeping each individual component relatively simple in design and manufacture.
Solution Approach 2:
The coupling section serves multiple functions: it connects the handle and attachment tool, compensates for tolerance variations, and maintains assembly precision. This multi-functionality is achieved through a relatively simple structure that provides both mechanical connection and tolerance compensation.
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 solution enables more flexible and cost-effective manufacturing by allowing for minor deviations in part dimensions and alignment, ensuring reliable assembly and functionality of multi-component personal-care implements while maintaining necessary precision.
Implementation Method 1
at least one first magnetic coupling element mounted adjacent at the free end of the drive shaft for connection, by magnetic interaction, with at least one second magnetic coupling element of a replaceable attachment tool
Data Source
AI summary
A coupling section for coupling a handle of a personal-care implement and a replaceable attachment tool includes a drive shaft having a free end terminating in a bushing; a first magnetic coupling element mounted adjacent to the bushing; a tolerance-compensation element having a through-hole sized to receive the drive shaft therethrough and mounted adjacent to the bushing. The free end of the drive shaft is disposed in the bushing so that there is a space between an inner surface of the bushing and an outer surface of the drive shaft's portion disposed therein, so that a position of the drive shaft can be adjusted inside the bushing during assembly. The tolerance-compensation element, which at least partially encircles the drive shaft, is affixed to the drive shaft and to the bushing. A handle of the personal-care implement and a process of making the handle are also disclosed.