Lock apparatus

A lock apparatus, comprising:

• a lock device which has a lock shell and a cylindrical lock core unit received in said lock shell, said lock core unit having an axial key hole and being provided with a latch actuator;
• and
• a coded key which is extendible into said key hole of said lock core unit and which is operable so as to permit rotation of said lock core unit relative to said lock shell for moving said latch actuator from a locking position to an unlocking position, said key having a head portion and a shank portion that extends from said head portion, said shank portion having a cross-section in the form of a circular sector with first and second planar surfaces that extend along length of said shank portion, and a curved surface that interconnects said first and second planar surfaces and that has an arc length greater than 180.degree., said shank portion being formed with a plurality of key bit projections and key bit grooves on one of said first and second planar surfaces, said key bit projections and said key bit grooves having inclined actuating surfaces that form different angles with said one of said first and second planar surfaces to set code of said key, said angles being in a range from 0.degree. to about 180.degree..