Sprue bush with strong adaptability and anti-overflow function

The sprue bush with the strong adaptability and the anti-overflow function comprises a top device, the lower end face of the top device is fixedly connected with a bottom device, and the top device comprises a sealing cover, a threaded column, a nut, a positioning column, an inserting hole, a positioning hole, a first positioning groove, a connecting hole and a positioning block. The sealing cover is arranged on the upper portion of the top device, and the positioning columns are symmetrically and fixedly connected to the inner end face of the sealing cover. The movable block is not fixed in the movable groove by releasing threaded connection of the fixing screw, then the movable plate is pulled, and therefore the device can adapt to different sizes and is fixed through the fixing screw after adjustment is completed, and the sealing cover is connected to the surface of the positioning block in a sleeving mode. And the positioning column is slidably connected into the first positioning groove for positioning,