Mechanical constant-resistance single prop continuous prop lifting pre-tightening device and method

A continuous prop lifting pre-tightening method for mechanical constant-resistance single prop having a piston rod, comprising the following steps:

• 1) connecting the two ends of an oil pipe and the two ends of an oil pipe to oil ports of a continuous prop lifter and a manual pressurizing pump;
• 2) removing prop rod clamping bolt and clamping nut, and prop casing clamping bolt and clamping nut, so that a prop rod clamping hoop and a prop casing clamping hoop having two leaves are in an open state;
• 3) fitting the two leaves of the prop rod clamping hoop and the prop casing clamping hoop over a prop rod and a prop casing of the single prop respectively;
• 4) inserting the prop rod clamping bolt and the clamping nut, the prop casing clamping bolt and the clamping nut into the prop rod bolt hole and the prop casing bolt hole respectively, closing and locking the prop rod clamping hoop and the prop casing clamping hoop respectively;
• 5) setting an oil circuit control switch in an manual pressurizing pump to an oil supply position, and pressurizing continuously by means of a manual pressurizing pump handle, so that the piston rod extends out and a conical bush assembled inside the prop rod clamping hoop is squeezed and clutches the prop rod, and thereby the prop rod of the single prop is lifted, meanwhile, observing the indication on an pressure meter to ensure the indication is within a rated operating pressure range;
• 6) terminating the application of pre-tightening force if the force on the single prop reaches preset pre-tightening force;
• if the single prop doesn't come into contact with the roof to be supported, setting the oil circuit control switch in the manual pressurizing pump to an oil return position and relieving the pressure continuously by means of the manual pressurizing pump handle, so that the piston rod retracts and the conical bush is decoupled from the prop rod;
• when the piston rod retracts completely, setting the oil circuit control switch in the manual pressurizing pump to the oil supply position, and applying pressure continuously by means of the manual pressurizing pump handle again, so that the piston rod extends out again, the conical bush assembled inside the prop rod clamping hoop is squeezed and clutches the prop rod, and thereby the prop rod of the single prop is lifted again;
• 7) terminating the application of pre-tightening force if the force on the single prop reaches the preset pre-tightening force;
• if the single prop still doesn't come into contact with the roof to be supported, repeating the step 6 till the preset pre-tightening force is reached.