Key plate and method for manufacturing the same

A key plate for insertion into a keyhole formed in a cylinder lock containing a plurality of tumblers movable between a normally locked position and an unlocked position, the key plate comprising a grip portion and a keyhole insertion portion formed in such a manner as to extend from a leading end portion of said grip portion, said keyhole insertion portion including two streaks of cord grooves formed in a flat surface thereof, said key plate being structured such that, when said keyhole insertion portion of said key plate is inserted into the keyhole formed in the cylinder lock, said respective cord grooves respectively press against the plurality of tumblers moving the tumblers from the normally locked position to the unlocked position to thereby allow said cylinder lock to be locked and unlocked, wherein a connecting groove connects respective rear end portions of said two streaks of cord grooves.

A method for manufacturing a key plate, in which said key plate is clamped on a mounting member fixed onto a table of a milling machine, and said key plate is milled by a milling cutter starting on the leading end side thereof, said method comprising the steps of:

• milling a flat surface of said key plate with a given cutting depth to thereby form one of two cord grooves;
• then, milling said flat surface continuously from the rear end portion of said one groove to thereby form a connecting groove;
• and further, milling said flat surface continuously from said connecting groove to thereby form the rear end portion of the other groove and toward the leading end portion thereof, whereby two streaks of cord grooves and said connecting groove can be worked continuously.

A key plate, comprising:

• a key plate body extending longitudinally and having a grip portion and a keyhole insertion portion connected to the grip portion, the keyhole insertion portion including a flat surface with a generally U-shaped groove formed into the flat surface, the generally U-shaped groove having a longitudinally-extending first cord groove, a longitudinally-extending second cord groove and a transversely-extending connecting groove disposed adjacent the grip portion and interconnecting the first cord groove and the second cord groove.