Lipstick Case Flexible Lip Torque Control
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Solution Overview
Problem
Lipstick cases face challenges in achieving an optimal torque for rotating the inner body relative to the outer body, leading to either unintended stick ejection due to low torque or user fatigue from high torque requirements, and existing solutions like lubricants or flexible lips suffer from dimensional dispersion issues causing variability in torque and quality perception.
Innovation Solution
A lipstick case design featuring a flexible lip with inclined sections that absorb dimensional differences, providing a consistent braking torque by bending during rotation, thus stabilizing the torque across manufacturing variations without increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flexible lip is used to control torque between inner body and outer body, then rotation control is improved, but dimensional dispersion causes variability in torque and quality perception
Solution Approach 1:
The patent changes the geometric parameters of the lip, specifically introducing an inclined section with a defined angle relative to the radial direction. This parameter modification allows the lip to compensate for dimensional variations while maintaining consistent torque control across different manufactured cases.
Solution Approach 2:
The patent adds a new dimensional aspect to the lip design by incorporating an inclined section that extends axially rather than purely radially. This dimensional change transforms the contact mechanism from a simple radial bearing to an inclined plane interaction, enabling torque control that is less sensitive to radial dimensional dispersion.
2Ease of operation
If torque between inner body and outer body is made too low, then ease of operation is improved, but unintended rotation and stick ejection occur
Solution Approach 1:
The patent modifies the friction parameter by changing the contact geometry to an inclined section. This parameter change optimizes the balance between friction force (preventing unintended rotation) and required torque (maintaining ease of operation), resolving the contradiction between operational ease and rotational stability.
3Reliability
If torque between inner body and outer body is made too high, then rotation control stability is improved, but user fatigue occurs due to significant force requirement
Solution Approach 1:
The patent optimizes the inclination angle parameter of the lip section to achieve the desired torque balance. By carefully selecting this geometric parameter, the design maintains sufficient friction for rotation stability while minimizing the force required by the user, thus preventing fatigue.
4Adaptability or versatility
If the transverse dimension of the lip is increased to absorb dimensional differences, then adaptability is improved, but torque between inner body and outer body increases
Solution Approach 1:
The patent resolves this contradiction by shifting the adaptability mechanism from the transverse dimension to the axial dimension through the inclined section. The lip absorbs dimensional differences through its axial inclination rather than increased transverse size, thereby maintaining lower rotation torque while preserving adaptability to manufacturing variations.
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 ensures a consistent and adaptable braking torque, reducing variability in user experience and perceived quality across different cases, while maintaining ease of use and minimizing manufacturing complexity.
Implementation Method 1
The lip thus makes it possible to impose a minimum torque by friction to obtain rotation
Implementation Method 2
the inclined section of the braking portion is stressed in bending in the direction of rotation around the main axis of the outer body relative to the inner body
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a case (1) for a stick of material to be applied by friction, in particular a stick of lipstick, including: a hollow cylindrical inner body (2), having a main axis (X), open at a proximal end (5), capable of receiving the stick of material; a hollow cylindrical outer body (7), having a main axis (X), open at a proximal end (10), into which the inner body (2) is inserted such as to pivot relative to the outer body (7) about the main axis (X), an outer cylindrical surface (4) of the inner body (2) facing a cylindrical inner surface (8) of the outer body (7); the case also including at least one flexible lip (34) for controlling the rotation torque about the main axis (X) of the inner body (2) inside the outer body (7).