The locking tongue is the original locking mechanism with a tacit cooperation with the lock beam. The tongue part and the tongue groove of the lock beam are combined. When the lock beam is pressed down, the ramp is used to synthesize the pressure of the lock beam, and the base plane of the lock tongue is used to prevent the upper jump of the lock beam. The opening function of the lock is completed by the matching of the groove at the bottom of the lock tongue and the lock core. At the same time, the rotation of the lock core is not driven when the lock tongue is compressed by the lock beam.