casing 1 a mounting plate 6 and a lock cylinder 7 the casing 1 is a hollow rectangular member having an opening 10 in one end there the top and bottom sidewalls of the opening open end 10 of the casing 1 are fastened pivotally with the mounting plate 6 by pivot pins 62 so that the casing 1 can be turned relative to the mounting plate 6 the lock cylinder 7 is provided at the bottom side of the casing 1 the mounting plate 6 and the jamb plate 8 are respectively fixedly fastened to a door panel a and a doorjamb b see fig7 the jamb plate 8 has a bolt 81 perpendicularly extended from the front side the bolt 81 has a head 82 referring to fig2 and 3 and fig1 again the doorplate assembly l is comprised of the aforesaid casing 1 a locating frame bar 2 a movable frame bar 3 a top locking strap 4 a bottom locking strap 5 the aforesaid mounting plate 6 the aforesaid lock cylinder 7 and a link 73 the other end opposite to the open end 10 of casing 1 is a close end 11 the casing 1 has a sliding slot 12 longitudinally extended from the close end 11 to the open end 10 in the front sidewall a back hole 14 in the back sidewall two pivot holes 13 in the top and bottom sidewalls corresponding to the open end 10 and two beveled guide edges 101 formed in the front sidewall corresponding to the open end 10 to expand one end of the sliding slot 12 the locating frame bar 2 is a hollow rectangular frame bar fitted into the casing 1 having a longitudinal sliding.