Experiment And Analysis Study On Percussion Device Of CHF-20 Percussion And Rotary Reverse Circulation Drilling Rig

Abstract: With the fast development of our national economic construction and the implementation of West-China development strategy, the infrastructure's construction of our country speeds up. In recent years, the foundation design of skyscrapers, underground facilities, bridges and quay presents a trend of maximization, that is, large diameter piles foundation has replaced group foundations. Meanwhile, in the China's strategy to develop its western regions, it was infrastructure construction that carried on at first. Thus, projects of building western railways and bridges become numerous, and so does the demand of drill rigs. At present, large-calibre engineering equipments for pile foundations of our country mostly adopt the single function rig, namely single-rotation rigs or single-impaction rigs. Such rigs often result in lower efficiency and longer period while drilling in complicated stratum. Co-developed by Jilin University and Jilin Mining Mechanical Factory, the CHF-20 rig realized the targets of rotation and impaction. In piles engineering, there are two methods to slag: circulation and anti-circulation. When compared to each other, the latter possesses priorities such as a higher efficiency , lower power consumption, less bit wear and better well completion. With the diameter and depth of drilling well increasing gradually, it is more difficult to drag, which demonstrates the circulation technology's superiority instead. This paper has been trying to analyze three kinds of circulation ways separately: pump-suction anti-circulation, efflux anti-circulation and gas anti-circulation. Percussion device is a main component of impaction rig, by contrast, slot and crank beam percussion device can realize automatic impaction, which not only lightens worker's labour intensity but also improve construction efficiency, so it possesses original superiority. This paper analyzed slot and crank beam percussion device's performance, and then draw conclusions that the second kind (α2>α1 ) bludgons is superior to the first type impaction organization. Furthermore, this paper has tried to analyze the relationship between impaction course of drilling tool and the movements of oscillating sheave. While drilling, the synchronism of one pair of ropes is a steady important factor that guarantee the stability of bit's impaction. The CHF-20 type impaction-anti-circulation engineering rig adopts automatic and simultaneous winching to solve double ropes'synchronous problem while impacting. The article analyses structure, principle and forces balance of both bevel gear and straight gear simultaneous winching. Weight of the drilling tool, the stroke and frequency of striking are three basic craft parameters in impaction drilling. This paper carried on theoretical calculation toward the two parameters of impaction frequency and stroke, getting the craft parameters of the corresponding stratum . Through analyzing and calculating we can draw that there are certain match relations between frequency and stroke to assault, propose, to different strata , it should be different to assault frequency and stroke at the same time . The author carried on the test on the CHF-20 type impaction anti-circulation engineering rig in the large-way-Alben bridge pile...