The structure press is mostly horizontal. According to the structure type, the hydraulic machine has two columns, four columns, eight columns, welded frame and multi-layer steel strip winding frame, and the medium and small vertical hydraulic machines are also C-frame type. The C-frame hydraulic press has three sides open for easy operation but poor rigidity. The welded frame hydraulic press for stamping has good rigidity and is open at the front and rear but closed at the left and right. In the vertical four-column free forging hydraulic machine of the upper transmission, the cylinder is fixed in the upper beam, the plunger is rigidly connected with the movable beam, and the movable beam is guided by the column, and moves up and down under the pressure of the working fluid. There is a workbench on the beam that can move back and forth. An anvil and an anvil are respectively installed under the movable beam and on the work surface. The working force is supported by a frame composed of upper and lower beams and columns. Large and medium-sized free forging presses driven by pump-accumulators often use three working cylinders to achieve three-stage working force. A balance cylinder and a return cylinder that exert an upward force are also provided outside the cylinder.