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The Face Design of DTH Drill Bit
Jul 30, 2018

As fuel prices continue to rise, the efficiency of construction machinery has become a very important indicator in engineering projects. The rock drilling machine with the choice of efficiency should be equipped with high-quality rock drilling tools.

       In the rock drilling operation, a series of factors such as the end face structure of the down-the-hole drill bit, the shape of the powder discharge groove, the tooth shape and size of the cemented carbide, and the angle of the teeth of the edge tooth directly affect the rock drilling efficiency and the smoothness of the wall of the blasthole. As well as the life of the drill bit, it is required to select different DTH drill bits according to different drilling methods and rock types.

      In order to improve the rock drilling efficiency and the service life of the drill bit, there have been some changes in the structure of the medium and high pressure down-the-hole drill bit in foreign countries in recent years, such as the partial adjustment of the tooth structure of the end face of the drill bit to improve the rock drilling speed; The tooth height is increased to facilitate the rapid removal of cuttings, reducing the secondary crushing rate, and also making the bit alloy teeth easy to grind; the length of the top of the drill bit is shortened to avoid stuck, broken handle and top block Phenomenon; At the same time, the anti-fatigue strength requirements of steel for medium and high pressure down-the-hole drill bits are more stringent.

      The shape of the end face of the down-the-hole drill bit is directly related to the rock drilling efficiency and the service life of the drill bit. At present, the medium and high pressure down-the-hole drill bits commonly used are mainly used in five end face shapes: a flat drill bit, a fast rock drill bit, a convex/elastic bit, a medium core concave drill bit and a rocket type drill bit.


       Planar drill bit (Fig. la): The drill bit is relatively rugged and suitable for drilling hard and extremely hard rock. It is also suitable for medium hard rock and abrasive rock. The drill bit uses a larger diameter ball-toothed alloy with a powder discharge groove on the head to effectively remove rock chips.

       Fast drill bit (Fig. lb): The core teeth of the drill bit are spring teeth, the side teeth are ball teeth, the larger powder discharge holes and the powder discharge groove are arranged, and the end faces are flat. This type of bit has a higher rock drilling speed when drilling hard rock and hard abrasive rock.


       Spherical concave drill bit (Fig. 2(b)): This type of drill is divided into two shapes, a concave structure and a concave double-sided tooth structure, using spherical tooth-shaped alloy teeth. Concave structure shape The middle part of the end face of the drill bit is micro-recessed conical shape, which is most suitable for drilling rock formations with medium hardness and hardness, low abrasiveness and broken geological structure. The drilling deflection can be well controlled during drilling. The concave bilateral tooth structure shape is primarily used for downhole drills with diameters greater than 203 mm (8 inches). The structural drill bit is concavely fitted with a double staggered scalloped alloy with a reinforced double-sided tooth structure for hard and hard, abrasive and fault geological formations.


Rocket type drill bit (Fig. 3): This is a new type of end face joint introduced by foreign downhole drilling tool manufacturers in recent years.

It has a diameter of 90~115mm and has a high rock drilling speed for soft rock and medium hard rock. A spheroidal shape alloy drill bit is used for drilling hard rock and abrasive rock, and a resilient tooth shape alloy tooth drill bit is used for drilling soft rock.

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