Double-wedge type hydraulic expansion shaft structure

The invention provides a double-wedge type hydraulic expansion shaft structure used in the field of rolling mill equipment, which comprises an oil cylinder, a piston, an adjusting nut and a connecting sleeve, a core rod is slidably arranged in the middle of a hollow main shaft in a penetrating manner, the piston of the oil cylinder is fixedly butted with the front end of the core rod, and the rear end of the core rod is connected with four axial wedges through a cross fork head; cross-shaped axial sliding ways are arranged on the outer side of the rear section of the main shaft, the axial wedges are correspondingly arranged in the four axial sliding ways, the outer sides of the wedge faces of the axial wedges are matched with wedge faces of the radial wedges, the inner side faces of the axial wedges make sliding contact with the main shaft, and the radial sliding ways are arranged at the front end and the rear end of each radial wedge. The guiding device is used for guiding the radial wedge to convert the axi