Double-loop secondary expansion jack and application method

Abstract

The invention discloses a double-loop secondary expansion jack and an application method, and is suitable for underground coal mines. The double-loop secondary expansion jack comprises an upper piston jack and a lower piston jack; a fastening expansion device is arranged between the upper piston jack and the lower piston jack; hydraulic oil is fed in an ejector expansion liquid inlet cavity to realize primary expansion and hydraulic locking; hydraulic pressure is injected in a jacking anchorage pipe expansion liquid inlet cavity to realize secondary expansion and hydraulic locking; after expansion is finished, hydraulic oil is released in a jacking anchorage rod de-anchoring liquid return cavity to realize jacking anchorage pipe de-anchoring; the hydraulic oil is controlled to feed in a jacking press de-anchoring liquid return cavity to realize jacking press de-anchoring so as to finish whole expansion process; and an expansion liquid feeding hydraulic loop and a de-anchoring liquid return hydraulic loop are separately arranged on two sides of the jack. The double-loop secondary expansion jack is simple in structure and excellent in matching property with an anchor rope lock, improves effective prestress of a lock and a lock ring on a tray, improves the locking firmness degree of a lock cylinder of the lock, further improves the roof support quality, and guarantees the roof safety in construction.

Description

technical field [0001] The invention relates to a double-circuit secondary expansion jack and a use method thereof, and is especially suitable for a double-circuit secondary expansion jack used underground in coal mines and a use method. Background technique [0002] Nowadays, during the production and construction of the first-line roadway in coal mines, the standard problems of locks and the matching of locks and pump jacks are seriously ignored. I mistakenly think that the reading of the tension pump is the prestress size provided to the roof, and the actual loss is 50%-70%. Some Ф17.8×6200mm anchor cables require a prestress of 130KN, and the actual applied pressure is only 40-65KN, while ordinary rebar anchors The torque value of the rod is 300N.m, and the actual construction prestress is 60-70KN. Therefore, the pressure of some anchor cables on the roof construction is actually not as large as the prestress provided by one anchor rod. There is a serious roof safety haz...

AI Technical Summary

Problems solved by technology

[0007] At present, all jacks on the market are single-circuit one-time rising and pulling jacks. The jacking anchor pipe and the jacking pressure device are mechanically connected as a whole. The press moves upward synchronously, and the jack can only be raised and pulled once. In the process of raising and pulling, the loss of prestress is too large due to the quality of the lock and the matching problems between the lock and the jack described in the background technology above.

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