Maintaining device for oil well casing

The utility model relates to a maintaining tool for casings, in particular to a maintaining device for an oil well casing. According to the technical scheme, the maintaining device for the oil well casing comprises a sliding valve, a bumper jar, a hydraulic cylinder, a piston, a piston rod, a rigid expanding head, an elastic expanding head, a guide head and a rotating joint, the sliding valve is connected to the bumper jar, the bumper jar is connected with the hydraulic cylinder, the piston is arranged in the hydraulic cylinder, the piston is connected with the piston rod, the lower portion of the piston rod is connected with the rotating joint, the rotating joint is connected with the rigid expanding head and the elastic expanding head, and the elastic expanding head is connected with the guide head. The maintaining device for the oil well casing has the advantages of being easy to use and good in maintaining effect, guaranteeing normal production of an oil well, improving production efficiency of the oil we