A frame for a hydraulic apparatus includes at least two supporting pillars parallel to each other, a supporting assembly mounted on the at least two supporting pillars, and a link mechanism mounted on the supporting assembly and coupling the core plate to the adjustable die plate. The supporting assembly includes a fixed die plate, an adjustable die plate slidably, and a core plate. The fixed die plate includes a periphery sidewall and a surface perpendicular to the periphery sidewall, the fixed die plate defines a ring-shaped indentation in the surface and extending along a circumferential direction of the fixed die plate, the fixed die plate further defines at least two first through openings interconnected with the ring-shaped indentation and cut through the periphery sidewall.