Metal Coffee Filter Hole Geometry for Uniform Extraction
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Solution Overview
Problem
Coffee filters with inconsistent hole size and geometry lead to variations in coffee extraction yield and taste, resulting in inconsistent brew quality due to factors like burrs, occlusions, and improper fabrication, which cause issues in achieving the optimal 20% extraction range for high-quality coffee.
Innovation Solution
A method of fabricating coffee filters with precisely formed tapered exit regions and uniform hole distribution, using micro-machining to ensure consistent hole size and geometry, and a system for qualifying filters to ensure uniformity, including a machine vision imaging system to assess hole circularity and cumulative area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used to create coffee filter holes, then manufacturing is simpler and faster, but hole size and geometry become inconsistent leading to variable extraction yield
Solution Approach 1:
The patent applies preliminary action by forming tapered exit regions and uniformity enhancement regions in the metallic member before drilling the holes. This pre-preparation of the substrate geometry ensures that subsequent hole formation produces consistent size and shape, eliminating the need for complex post-processing while maintaining manufacturing simplicity
Solution Approach 2:
The patent changes the physical parameters of the metallic member by creating zones with different properties: tapered exit regions that guide hole formation and uniformity enhancement regions that maintain consistent hole geometry. These parameter changes in the substrate enable precise hole formation through standard drilling processes
2Manufacturing precision
If micro-machining is applied to the first major surface to remove part of the hole uniformity enhancement region, then hole uniformity is improved, but manufacturing time and complexity increase
Solution Approach 1:
The micro-machining operation is performed as a preliminary step before hole formation, removing material to create the uniformity enhancement region. This advance preparation ensures that when holes are subsequently formed, they maintain uniform geometry without requiring additional corrective machining operations that would consume more time
Solution Approach 2:
The micro-machining process changes the surface parameters of the first major surface by removing material to a predetermined depth. This parameter change creates a controlled geometry that guides hole formation and ensures uniformity, enabling faster overall fabrication by eliminating the need for multiple iterative adjustments
3Manufacturing precision
If tapered exit regions are formed extending from the second major surface to interior vertices, then hole formation precision is improved, but the fabrication process becomes more complex
Solution Approach 1:
The tapered exit regions are formed as a preliminary structural feature in the metallic member before hole formation. This pre-created geometry serves as a template that guides the hole formation process, ensuring precise hole placement and geometry while using standard manufacturing equipment rather than requiring complex specialized processes
4Manufacturing precision
If hole uniformity enhancement region is provided between the first major surface and the vertices of exit regions, then hole size consistency is improved, but manufacturing complexity increases
Solution Approach 1:
The hole uniformity enhancement region is created as a preliminary structural feature by removing material to a predetermined depth before hole formation. This pre-prepared zone ensures that holes formed within it maintain consistent size and geometry, while the process remains relatively simple as it uses conventional material removal techniques followed by standard hole formation processes
Data Source
AI summary
A coffee filter includes a metallic member having a flat portion in which tapered exit regions are formed that extend from the bottom of the flat portion to vertices interior to the flat portion. The flat portion is provided with a hole uniformity enhancement region between the top of the flat portion and the exit region vertices that are interior to the flat portion. The top of the flat portion is micro-machined to remove a part of the hole uniformity enhancement region to a predetermined depth into the hole uniformity enhancement region. Holes are formed in the top of the flat portion extending from the micro-machined top of the flat portion through the hole uniformity enhancement region to the vertices of the tapered exit regions. The predetermined depth of the micro-machined top of the flat portion is selected to prevent the micro-machined top of the flat portion from meeting the tapered exit regions to promote and maintain uniformity of the holes.