Upper part for a spice mill
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Solution Overview
Problem
Existing spice mill upper parts made from plastic materials face deformation and damage during the injection moulding process due to forced demoulding, limiting the use of brittle plastics and increasing production waste, as they require circumferential projections that are prone to deformation when removed from the moulding tool.
Innovation Solution
The introduction of an elastically deformable snap element aligned with the opening of the upper part allows for a rotatable connection to the lower part, enabling the snap element to be formed within the injection moulding tool and removed without deformation, allowing for the use of brittle plastics and improved holding action through multiple snap elements arranged symmetrically around the axis of rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a circumferential projection is provided on the lower edge of the upper part for rotatable connection, then the holding action on the lower part is improved, but the upper part is deformed during forced demoulding from the injection moulding tool
Solution Approach 1:
The connection between upper and lower parts is segmented from a single circumferential projection to multiple discrete snap elements (at least two, preferably three or four) distributed around the circumference. Each snap element independently provides holding action while allowing uniform stress distribution during demoulding, preventing deformation of any single connection point.
Solution Approach 2:
Instead of forming the connection element as an integral part of the upper part that must be forcibly removed, the snap elements are designed to be formed within the mould cavity and then released through openings in the upper part. This inverts the traditional demoulding approach, allowing elements to be created inside the mould and extracted through separate pathways.
2Ease of manufacture
If the circumferential projection is kept small and designed without undercuts to facilitate easy removal, then the production waste is reduced, but the holding action on the lower part is weakened
Solution Approach 1:
The snap elements incorporate undercuts that extend in the radial dimension, creating geometric interlocking features. These undercuts allow the elements to be formed with complex 3D geometries including recesses and protrusions that provide strong holding action, while the elements are still removable through the openings by elastic deformation during demoulding.
Solution Approach 2:
The snap elements are designed with elastic deformability, allowing their physical state to change during demoulding. The elements can be elastically deformed to pass through the openings during removal, then return to their original shape to provide strong holding action when connected to the lower part. This parameter change enables both easy removal and strong connection.
3Adaptability or versatility
If relatively brittle plastic material is used for the upper part, then the material properties are optimized for the application, but the material is damaged or destroyed during forced demoulding
Solution Approach 1:
Openings are pre-formed in the upper part design, creating release pathways before the demoulding process begins. These openings allow the snap elements to be extracted from the mould cavity without requiring forced removal of the entire upper part, preventing stress concentration and damage to brittle materials during the demoulding operation.
Solution Approach 2:
The openings in the upper part serve as intermediary pathways that mediate between the snap elements and the external demoulding force. Instead of applying force directly to the brittle upper part to remove the projection, the force is transmitted through the openings, allowing gentle extraction of snap elements without damaging the main structure.
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 minimizes production waste, prevents material deformation, and enhances the holding action between the upper and lower parts, enabling the use of brittle plastics like polylactide (PLA) while allowing for easy assembly and disassembly without forced demoulding.
Implementation Method 1
a preferably elastically deformable snap element is provided that is aligned flush with the opening in plan view
Data Source
AI summary
An upper part for a spice mill at least partly of a plastic material includes an upper cover surface with at least one opening, in particular a through-opening for ground spices, a circumferential lateral surface, and a milling element or a mounting for the milling element. A preferably elastically deformable snap-action element, by which the upper part can be rotatably connected to a lower part, is arranged so as to be flush with the opening in plan view.