Mechanical hydraulic double-acting expansion device suitable for expansion tube drilling

The invention provides a mechanical hydraulic double-acting expansion device suitable for expansion tube drilling. The device comprises an anchor, a hydraulic cylinder assembly and a variable-diameter expansion cone assembly; the lower end of the anchor is connected with the upper end of an insertion connection tube through a coupling, the hydraulic cylinder assembly comprises a hydraulic cylinder body and a piston tube capable of being arranged in an inner cavity of the hydraulic cylinder body in a movable and penetrating mode, the upper end of the hydraulic cylinder body is connected with the insertion connection tube through a cylinder body adjusting sleeve, the lower end of the hydraulic cylinder body is tightly attached to the piston tube which is arranged in an inner cavity of the cylinder body adjusting sleeve in a penetrating mode, the upper end of the piston tube is arranged in the insertion connection tube in an inserted mode and tightly attached to the inner side face of the insertion connection tube, a protruding ring is arranged on the outer side wall of the piston tube and divides the inner cavity of the hydraulic cylinder body into an upper cavity and a lower cavity, and liquid injecting holes communicated with the lower cavity are formed in the side wall of the piston tube; the variable-diameter expansion cone assembly comprises a sealed cone part and a variable-diameter expansion cone part, the upper end of the sealed cone part is connected to the lower end of the piston tube, and the lower end of the sealed cone part is connected with the upper end of the variable-diameter expansion cone part. By means of the mechanical hydraulic double-acting expansion device suitable for expansion tube drilling, construction operations of an expansion tube in a sleeve and an open-well system can be completed.