Hydraulic system of pipe rolling device and rotary-excavating drilling machine

The invention discloses a hydraulic system of a pipe rolling device and a rotary-excavating drilling machine. The hydraulic system is characterized in that an oil inlet of a main valve is connected with a hydraulic source; an oil return port is connected with an oil-return path; a first working oil port is connected with the free oil inlet end of a one-way balance valve; the free oil outlet end of the one-way balance valve is connected with a lifting oil port; a second working oil port is connected with a lowering oil port of a motor of the pipe rolling device; the hydraulic control end of the one-way balance valve is connected onto an oil path between the second working oil port and the lowering oil port; an oil inlet of a first overflowing valve is connected onto an oil path between the first working oil path and the free oil inlet end, and an overflowing port of the first overflowing valve is connected with an oil path between the second working oil port and the lowering oil port; an oil inlet of a second overflowing valve is connected onto an oil path between the free oil outlet end and the lifting oil port, and an overflowing port of the second overflowing valve is connected onto an oil path between the second working oil port and the lowering oil port. By implementation of the invention, the pipe rolling device can realize the functions of pipe rolling and pipe unrolling, and the rolled pipe can keep certain pre-tightening force.