Influence of Tungsten Carbide Button Bit on Rock Drilling Speed

The rock drilling speed is one of the important indicators for the quality of tungsten carbide button bit. In the case of fixed models, lithology, operating systems, etc., the geometric parameters of the bit have a great influence on the rotational speed. The geometric parameters of the button bit include its shape, number, diameter, the distribution of button, the powder discharge system, the tooth height, incline angle of side teeth and so on

At present, the button generally uses hemispherical teeth and bullet teeth, and the two types have their certain adaptability. The bullet teeth have a higher pressure ratio. Under the condition that the rock abrasiveness is not high and the impact energy of the rock drill is insufficient, the performance is better. Obviously, when the rock is tough and the impact energy is big, the solidity is not as good as that of the hemisphere. The number of teeth (especially the number of side teeth) is one of the most important parameters of the button bit.

When the impact energy is the same, the increase in the number of button can reduce the impact load on the single button and reduce the broken button while the rotational speed decreases within a certain range. The diameter of the side teeth is slightly increased, and the wear resistance and chipping resistance of the bit are remarkably improved. The inner arrangement of button bit in minor diameter is basically fixed when the number of side teeth is fixed. As for the large-diameter button bit, its inner arrangement is more selective, thereby improving the rock drilling speed.

When we use the pneumatic drill, the impact energy is insufficient and the rock is more tough. The more the teeth are, the worse the performance will be. When the air pressure is increased, the rock is soft, and the impact energy is sufficient, the button bit in the same diameter will perform better with more teeth. When the level of radial abrasion of the rock is very high, if the number of the side teeth is small and the teeth are thin, the ability of the button bit to resist radial wear and slow the premature valgus fragmentation of the side teeth is reduced, so the rock drilling speed is also obviously decreased.

The use of button bit has a certain adaptability. We must ensure that impact energy is sufficient and it can be applied in the soft and brittle rock when we use it. Its structure has a great influence on its performance. Under the condition that the impact energy of the rock drill is small and the rock has great toughness and high abrasiveness, it will be extremely ineffective and sometimes even cannot be used at all. (In this case, a special heavy-duty sheet-shaped bit should be used) With the sufficient impact energy, the diameter of side teeth should be as long as possible in order to delay the excessive exposure of the teeth. As for the bit in the major diameter, the incline angle of side teeth can be slightly larger and the tungsten carbide with great abrasion resistance should be selected. 

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