Reversible Flat Key Profiling with Inclined Milling Cutter
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Solution Overview
Problem
Existing methods for profiling the broad sides of reversible flat keys require multiple operations to create undercut groove walls, which is inefficient and limits the complexity of locking hierarchies.
Innovation Solution
A method where the cutter shaft axis is inclined at an angle to the key's longitudinal center plane, allowing for the creation of undercut groove walls in a single operation using a milling cutter with a cone surface, enabling the profiling of both broad sides simultaneously and allowing for variation grooves and ribs to differentiate locking systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a milling cutter with axis perpendicular to the broad side is used, then the groove walls have positive angles avoiding friction, but undercut groove walls cannot be produced
Solution Approach 1:
The patent changes the orientation parameter of the milling cutter axis from perpendicular to inclined at an angle α (5°-50°) relative to the longitudinal center plane of the key. This parameter change enables the production of undercut groove walls while the groove flanks are designed with angles greater than 90° to the key normal to avoid harmful friction.
2Manufacturing precision
If multiple operations are used to profile both broad sides with undercut grooves, then complete key profiling is achieved, but production time increases
Solution Approach 1:
The patent combines the profiling of both broad sides into a single operation by using a milling cutter with an inclined axis that can simultaneously machine both sides of the key as it passes through the clamping device, thereby reducing production time while maintaining complete key profiling.
Solution Approach 2:
The key is advanced periodically through the milling cutter in the longitudinal direction, allowing the rotating milling teeth to continuously engage and profile both broad sides alternately as the key moves through the machining zone.
3Adaptability or versatility
If the milling cutter axis is inclined, then undercut groove walls are produced, but the groove wall friction may increase
Solution Approach 1:
The patent carefully balances two parameters: the cutter axis inclination angle α (5°-50°) to produce undercuts, and the groove flank angle β (>90° to key normal) to minimize friction. The groove flanks are specifically designed with angles greater than 90° to the key normal direction to ensure that even with the inclined cutter, harmful friction is avoided.
4Ease of manufacture
If simple groove profiles are used, then manufacturing is easier, but locking hierarchy complexity is limited
Solution Approach 1:
The patent applies different groove and rib patterns to specific local areas of the key broad sides. Variation grooves and ribs are strategically positioned to create unique profiles for different locking systems and hierarchy levels, while maintaining the overall simple structure that can be manufactured with the inclined milling cutter.
Data Source
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AI summary
The method involves clamping a key blank (1) in a clamping device such that a broadside (3) of a rotating flat key lies freely. The key blank is clamped in a position that is rotated around a longitudinal central axis such that another broadside (3') lies freely. A miller shaft axis is inclined to a longitudinal plane (2) of the key blank around a tilt angle (phi), where the inclination angle lies between 10 and 40 degree. An undercut guide groove walls is formed by a rib of a milling tooth (16) of a miller (17). Independent claims are also included for the following: (1) a base profile for a rotating flat key (2) a rotating flat key comprising a locking system formed from a number of lock cylinders.