Connecting casing

The utility model discloses a jointing sleeve, comprising a sleeve body and an isolator in the sleeve body, wherein the sleeve body comprises two conical tubes whose bottoms are butted and the isolator is provided between the two conical tubes; the two conical tubes are respectively provided with an internal sliding tube which can slide along the inner walls of the conical tubes; the inner walls of the sliding tubes are cylinder; and two springs are mounted between the isolator and the sliding tubes. When in use, users should inserts the steel bars or steel tubes to be connected into the sliding tubes, select connecting sleeves of the type corresponding to the diameters of the steel bars or the steel tubes, tightly combine the inner walls of the sliding tubes with the steel bars or the steel tubes via the support function of the springs, and connect the two steel bars or steel tubes via the friction force between the steel bars or the steel tubes and the sliding tubes. The joint sleeve can be detached simply