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在日本,热力破岩法主要用于切割花岗岩。经验表明,热力方法比机械方法有效而且经济,其凿岩成本约比机械凿岩低30%。东京大学矿业研究所研制了切割花岗岩用的汽油压气火钻,还研究了火钻射流的热力特性。火钻的结构示于下图。喷管临界直径为11.4毫米,燃烧室直径为44毫米。火钻用空气冷却,汽油则采用高压氮气从燃料箱中压出。试验时燃烧室的压力为5～6公
In Japan, thermal rock breaking is mainly used to cut granite. Experience has shown that thermal methods are more efficient and economical than mechanical methods, and their rock drilling costs are about 30% lower than mechanical rock drilling. The Institute of Mining at the University of Tokyo developed a gas-pressure, gas-burned diamond for cutting granite, and also studied the thermal properties of the burnt jet. The structure of the fire drill is shown in the following figure. The critical diameter of the nozzle is 11.4 mm and the diameter of the combustion chamber is 44 mm. Fire drill air cooling, the use of high pressure nitrogen gas is squeezed out of the fuel tank. Test chamber pressure of 5 to 6 public