Research And Application Of Frictional Heat-Mechanical Energy Rock Fragmentation Theory And Technology

Thermo-mechanical rock fragmentation drilling technology (TM) is a kind of new drilling method, which connects traditional thermal rock fragmentation with mechanical rock fragmentation. It abandoned the classical old theory that it is harmful that friction between cutting tools and rock brings heat energy. It used friction heat energy to crack rock, then cut rock by tungsten carbide tools (or impregnated diamond block) and gained a great increase in cracking ratio of rock. It is significant because of its high rock fragmentation's efficiency. Ninety percent of bit's nonproductive power loss converts to friction heat energy at the course of pure mechanical rock fragmentation, then the part of energy is flushed by washing fluid. Thermo-mechanical rock fragmentation drilling tool may use the energy to heat rock, which not only reduces energy capability what is needed, but also increases mechanical drilling rate. Its rate enhances 2-3 times than its conventional drilling. So thermo-mechanical rock fragmentation drilling tool may extensively enhance drilling efficiency and increase total capacity usage ratio. Thus the theory and technology's application makes society and economical benefit obvious. The research about thermo-mechanical rock fragmentation is significant. Firstly it may extensively enhance tungsten carbide or diamond cutting tool's rock fragmentation speed, reduce rock fragmentation cost,increase rock fragmentation efficiency and enlarge the scope of tungsten carbide coring drilling ,which makes tungsten carbide rock fragmentation drilling tool replace expensive diamond drilling tool cutting to drill rank Ⅺhard rock. secondly its applied range is wide. It can be applied to geology drilling ,oil and gas well drilling ,various engineering hole hard rock drilling and underground ,tunnel driving etc rock fragmentation. Consequently it offers a kind of high efficient ,lower power-wasting newly rock fragmentation method. Main ideas: first, we must know temperature conditions what thermo-mechanical is needed after we studied heat energy effect on rock strength ,hardness ,abrasiveness; then mensurated if thermo-mechanical drilling tool arrived to its needed temperature, and determined its hole bottom temperature field and built mathematical model; thereafter we studied the means of selecting fetal material and developed resistant to friction and refractory new material; and ascertained its optimum drilling rules parameters, furthermore generalized its law; did a series of tisco manganese steel bit tests and came to a conclusion; continued to perfect the design of thermo-mechanical rock fragmentation drilling tool (including coring drilling tool); finally did field tests. Thermo-mechanical rock fragmentation theory is a newly drilling technology based on mechanical rock fragmentation. The paper has studied its mechanism especially about rock temperature field. The key of the theory is to found hole bottom temperature field and its mathematical model through analysis and study. Methods of computer planning solution are applied to calculate optimum compounding of bit fetal material. We designate four bit fetal indexes of physical mechanics and gained compounding of fetal material by methods of computer planning solution. And we have obtained conclusion after we finished test of the fetal material of new compounding. Also we have analyzed and calculated some drilling technology parameters, such as drilling pressure P, rotational speed N, and flow rate Q, and come to a conclusion that they affect drilling efficiency and obtained their optimum match parameter, bit life and drilling aging by multiple tests. We have done experiments with Tisco manganese steel bit which is applied to thermo-mechanical rock fragmentation drilling. We have designed and processed a set of drilling tool that is fit for field test after indoor simulation test and obtained a good result. 1.It is known that compression strength of most rock is falling while temperature is rising. Especially, rock strength changes significantly when temperature is up to 600oC. Consequently we have testified the method's feasibility and deduced that a lot of rock's ideal cracking temperature is above 600 oC. There is two main reasons that cause rock strength's descending: one is non-uniform expansion orchemical decomposition, heat or gas expansion, phase-change of mineral when rock is heated. The other is hot impact action which is caused by heat shock chilling and heating or the two action co-operation cause rock strength's reducing. Granite belongs to difficultly slip stratum because of its high hardness and strength, but its these features are wide-range reduced for quartz phrase change takes place among 573-580 oC, so it is fit for thermo-mechanical rock fragmentation drilling. Thermo-mechanical rock fragmentation mechanism has two forms: one is heat stress action about 600 oC which causes strength's reducing and enhances fragmentation efficiency. The other is that rock surface temperature arrives to fusion state among 800 oC -900 oC and enhances drilling efficiency. Thus there is contradiction between rock fragmentation efficiency and bit life. So we must continue to study and produce high-temperature friction material to increase bit life and drilling efficiency. We can found temperature equation to determinate relation of temperature T and depth Z if we know temperature has a effect on rock strength. Experimental result accorded with calculation result of mathematical model, which it is right and it can calculate certain deep temperature. 2.The dissertation used blend rule to direct mathematical model foundation and method of planning solution to calculate optimum compounding of fetal body. We choose an optimum compounding after synthetized all of influencing factors: Ni10, ZQSn(6-6-3)38, Mn5.4, SiC4.6, WC42(digit of these is percentage) 3.Experiment of Tisco manganese steel bit. Abrasion of Tisco manganese steel have three states: surface contact abrasion between hardware and scouring between flowing gas or liquid and metal surface. High manganese steel has a main feature that its surface is hardened quickly and produces high density crystals under attacking violently and extrusion contact. But it still holds its good toughness and plasticity order. The test shows that Tisco manganese steel bit is good that it isn't easy to break-up for its integrality in application. So Tisco manganese steel bit is convenient and cheap because it has not bit fetal body. 4.Thermo-mechanical rock fragmentation bit may drill grade 6-9 rock. Several experiment obtained the following optimum range of drilling parameter: (1). Pump pressure 18-22KN is best range whichdrill penetration rate increases with pressure's rising. (2). Rotary speed 450-665r/min is wonderful scope that penetration rate increases with rotary speed's rising. (3). Penetration rate grows with pump pressure's increment in 1.2-1.5MPa. (4). Little flow rate leads penetration rate's increase in 6-8L/min. (5). When P×N=1.33×106kgr/min and Q=6-8L/min,thermo-mechanical rock fragmentation drilling efficiency is better than other states. We have gained three chief paths of enhancing drilling efficiency: increasing the product of P, reducing flow rate and improving dit's structure to enhance friction coefficient between friction part and rock. For example, the effect adopt acicular alloy or glomerocryst diamond to friction part are better than alloy block. There is a function relation between P,N,Q and penetration rate, so we may adjust diversity parameter to get the match penetration rate. 5.The appraisal of thermo-mechanical rock fragmentation technology: (1). Drilling efficiency is high and its cost is low. In drilling IX grade granite, diamond drilling penetration rate may to 1.8m/h, while thermo-mechanical drilling may to 3m/h that its life is to 14.5m. (2). Bit construction is simple and its generating method of heat energy is reliable. The technology adopts friction to get heat energy unlike the technology of pure hot rock fragmentation. Its cost is fall down and its equipment is simplified. (3). It is better than tungsten carbide bit in drilling range and effect. (4). We take P×N as a parameter that is equivalent with speed rate and temperature effect and we may know that enhance rotary speed to instead of high bit weight. (5). Thermo-mechanical bit is heated while it contacts with rock and produce heat energy that we may calculate. That is to say, friction between two material produces heat energy is down with elastic ratio's rising. The idea is unlike to friction part as a heater in nature, which is important direct significance to study high-temperature material of friction part. 6.We have designed a new core drilling tool that add to a overflow valve, which satisfying the demand of removal cutting and producing heat effect. So we can apply it to production through indoor experiment. 7.We have obtained good result by field test.