Cylinder-lock key for master-key system - has curved portion leading to guide groove bottom and four or more straight guide faces extending in different directions

摘要

The grooved guide profile (12) has a curved portion (25) leading to its bottom There are also four or more straight guide faces (23, 24, 26, 27) extending in different directions, the width of each being between 0.2 and 1.3 mm. The curved portion can comprise a combination of circular, parabolic, hyperbolic or elliptical sections. Adjacent straight guide faces can include obtuse angles, and none of them can be vertical or horizontal. ADVANTAGE - Simple to produce, and very difficult to counterfeit.