Middle tightener

The utility model discloses a middle tightener, which is suitable for fixing a wire and an insulating column and comprises a bottom plate, a pressing plate, two J-shaped studs and fastening nuts. The bottom plate is in a long strip shape, a first arc-shaped groove penetrating through the bottom plate is formed in the middle of the bottom plate, and the central axis of the first arc-shaped groove perpendicularly intersects with the axis of the bottom plate in the length direction. The pressing plate is an S-shaped plate, a second arc-shaped groove which penetrates through the pressing plate and is matched with the first arc-shaped groove of the bottom plate is formed in the middle of the pressing plate, a through hole is formed in one end of the pressing plate, an open groove is formed in the other end of the pressing plate, and a screw of a J-shaped stud can penetrate through the through hole. The inner diameter of the open slot is matched with the outer diameter of a screw rod of the other J-shaped stud; and