Coffee Grinder Interlocking Plug Design to Reduce Burr Misalignment
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Solution Overview
Problem
Existing coffee grinders with interlocking plugs suffer from excessive 'play' or 'wiggle' between the plug and frustoconical burr due to manufacturing tolerances, leading to inconsistent grinding results, with some coffee beans being ground too fine while others remain under-grounded.
Innovation Solution
A coffee grinder design featuring an interlocking plug with tapered side surfaces and a cylindrical upper portion that securely engages a frustoconical burr, reducing lateral movement and ensuring proper alignment through a coaxial upper cylindrical surface, thereby minimizing variance in grind size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If flat side surfaces are used on the interlocking plug gears, then the structure is simpler to manufacture, but there is excessive play or wiggle between the plug and frustoconical burr
Solution Approach 1:
The invention changes the geometric parameters of the interlocking plug by transitioning from flat side surfaces to tapered side surfaces that are angled relative to the shaft axis. This parameter change allows the tapered surfaces to engage with corresponding tapered surfaces on the frustoconical burr, eliminating play and wiggle while maintaining manufacturability through standard machining processes.
2Manufacturing precision
If a frustoconical center post is used in the interlocking plug, then tapered side surfaces can engage properly, but the center post engages first and prevents proper seating of the side surfaces
Solution Approach 1:
The invention inverts the conventional design by using a cylindrical center post instead of a frustoconical one. This inversion allows the tapered side surfaces to engage first, guiding the frustoconical burr into proper alignment, while the cylindrical post provides stable support without interfering with the seating of the tapered surfaces.
3Ease of operation
If there is significant movement between the interlocking plug and frustoconical burr, then assembly is easier, but the burr gets pushed out of alignment during grinding
Solution Approach 1:
The invention applies preliminary action through the tapered side surfaces that guide and pre-align the frustoconical burr with the interlocking plug during assembly. This preliminary alignment action ensures proper positioning before the grinding process begins, preventing misalignment during operation while maintaining ease of assembly.
Data Source
AI summary
A coffee grinder has a housing that includes a ring burr, a shaft extending through the ring burr, a frustoconical burr, and an interlocking plug. An internal bore of the frustoconical burr has an upper cylindrical surface adjacent the top end, an interlocking portion adjacent the bottom edge, and a tapered side surface. The interlocking plug is shaped to extend through the internal bore of the frustoconical burr, and includes an upper cylindrical portion that fits through the upper cylindrical surface, and a lower portion that includes a sidewall surface which is also tapered such that the sidewall surface interlocks with the side surface of the frustoconical burr.