阿特拉斯科普柯钉锤钻具介绍.ppt

* Drill strings for Bench Drilling This shows the development of extension drilling - extension eq. in the 1960’s, SPEEDRODS during the late 1970’s and guide tubes during the 1980’s To this picture you can also talk about (but maybe not in this position): - Extension equipment is the cheapest to buy - Speed rods are more expensive, but also more efficient in transferring percussion energy. They are more rigid and facilitate hole straightness and they are also more suitable for rod handling systems. - TAC guide tubes are used when you encounter hole deviation problems. * * * * * * * One of the most common failure reasons for standard R 32 drifter rods is a breakage in the bit end, either right behind the bit skirt or slightly inside the bit. This is the most sensitive area on a rod and it is subjected to high bending stress during the drilling cycle, especially when starting a new hole. The bit is normally lost in the hole when this type of failures occurs. The hole has to be re-drilled causing lost time in the drilling cycle which in turn affects the productivity. * What did we do to increase the durability of the rods and make it easier to uncouple the bits? We invented the conical rope thread where we have a patent pending. We use a hexagonal 35 mm rod to increase the stiffness and durability, this means that we get 25% more material in the most sensitive area of the rod which gives an even higher increase in metal fatigue resistance. The front of the thread is 32 mm which means that it is possible to use a 45 mm bit. There is enough material in the most sensitive area of the bit to ensure a very good service life. * * Couplings The purpose of the coupling is to keep two threads well connected during drilling. The stress wave should not go through the coupling but through the connected ends of the string. The coupling is not made to take the full stress of the compressive stress wave and definitely not tensile stress waves going back up the string wi