The invention discloses a vertical
pile driver with a pre-digging function for mounting a highway protective fence in the technical field of protective fence mounting equipment. The vertical
pile driver comprises a movable base. A pre-digging
assembly is mounted on the left side of a weight box, a
pile driving
assembly is welded to the center of the bottom of a lifting plate, a pile foundation centering
assembly is welded to the bottom of the right side of a mounting frame, and a rubber buffer layer is bonded with the top of the weight box through glue. Due to the fact that the downward hammering force of an
impact block driven by a
telescopic cylinder is smaller than the downward hammering force of hydraulic cylinders, after pit digging and pile foundation pre-burying are completed, the hydraulic cylinders are used for hammering firstly, the hammering force is large, preliminary hammering is achieved, pile foundations are rapidly hammered into the ground; and before the pile foundations are hammered to the proper height, the hydraulic cylinders are closed, the
telescopic cylinder is started, slight hammering is carried out, and the pile foundations are slowly hammered into the ground, so that the situations that the hammering force of the hydraulic cylinders is too large, the downward hammering lengths of the pile foundations are too large, exposed parts of the pile foundations are short, and subsequent guardrail installation cannot be completed can be avoided, and that the extending lengths of the pile foundations are the same is guaranteed.