The basic requirements for teeth are high rock breaking efficiency and long service life. To meet this requirement, firstly, the geometric shape of the teeth should be reasonable; The second is that the material of the teeth should be wear-resistant and have sufficient strength.
At present, there are two types of teeth for cone drills: milling teeth (also known as steel teeth) and hard alloy teeth (referred to as insert teeth).
L Milling tooth profile
The teeth of the milling cone bit are integrated with the cone shell, which is formed by milling the rough cone. In order to improve the wear resistance of the teeth, hard alloy powder is applied to the tooth surface.
The tooth profile of milling teeth is mainly wedge-shaped teeth. The outer diameter retaining teeth can be made into P-shaped, T-shaped, or L-shaped shapes.
a. Wedge shaped teeth: suitable for crushing soft and medium hard formations with high plasticity, with teeth sharp angles ranging from 65-90. Those with small teeth sharp angles are suitable for soft formations, while those with large teeth sharp angles are suitable for harder formations.
b. Scoop Chisel: There is also a type of wedge-shaped tooth that is asymmetric on both sides and concave on one side, called Scoop Chisel, suitable for drilling soft formations.
c. Conical teeth: There are two types: single cone and double cone, which break rocks by crushing. The 60 ° -70 ° medium conical teeth are used to drill medium hard formations, such as limestone and dolomite. 90 ° cone and 120 ° double cone teeth are suitable for hard formations with high abrasiveness, such as hard sandstone and quartzite.
d. Triple edged teeth: formed by cutting a plane every 120 ° on the conical surface of double conical teeth, suitable for intersecting layers of hard and brittle formations and soft and plastic formations.
e. Spherical teeth: With high strength and wear resistance, they can crush and impact hard formations with high abrasiveness, such as flint, quartzite, basalt, and granite.
f. Projectile shaped teeth: It is a deformation of spherical teeth, with higher teeth but certain strength, suitable for hard formations with high abrasiveness.
g. Flat top shaped teeth: cylindrical teeth with chamfers at the ends, used only on the back cone of the tooth to prevent wear and maintain the gauge diameter.
h. Oblique wedge-shaped teeth: Basically wedge-shaped, but the tooth edge is narrow at one end and wide at the other end. Used on the outer teeth of drill bits in medium to soft formations. The wide side has high wear resistance and is installed on the outer edge of the drill bit to cut the wellbore wall and prevent the drill bit from becoming smaller.
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