The service conditions of the button bit are very harsh, and its service life directly affects the cost and efficiency of rock drilling. Because the button bit is composed of cemented carbide button embedded in the bit body, the failure mode of the button bit is mostly the failure of the carbide button. Therefore, the quality of the carbide buttons is crucial to the drilling life of the button bit.

The parameters related to the carbide button of the button bit mainly include the determination of the number and the diameter of the button and the selection of a reasonable button layout and button shape.

Determination of the number of buttons and button diameter

The number of carbide buttons and the button diameter of the button bit are directly related to the diameter, structure, and impact power of the rock drill. If the number of buttons is too many, it may cause the buttons to pass through each other or the steel wall is too thin and cannot be fixed.

Factors to consider for the size of carbide button diameters

1. Carbide buttons must have sufficient bending and impact resistance.

2. The wear resistance of carbide buttons.

3. The structural characteristics of the drill bit. The number of button and button diameters of small and medium diameter drill bits sometimes contradict each other, and the specific balance should be made from the economic point of view.

Principle of reasonable buttons distribution

The reasonable distribution of carbide buttons has an important influence on drill bit rock drilling.

The principles of buttons distribution are as follows:

1. Each button can fully play its role and wear evenly.

2. There should be enough steel body around the root of the button to ensure the solidity of the carbide button.

3. Button ring spacing can cover the surface of the rock and can be effectively broken at once, not to leave the rock wall of the cloth buttons characteristics.

Selection of carbide buttons shape

Carbide buttons withstand rotating alternating loads, impacts, torques, bending stresses, etc. Commonly used carbide button shapes include hemispherical buttons, parabolic buttons, conical buttons, etc. Because the hemispherical buttons under the rock gouge crush into radial, the stress distribution on the impacted rock is a more uniform and wide range. In the pressure into the rock, the reaction force between the rock surface and the button surface is compressive stress, so the other button is crushed solid. However, it is also easy to blunt, and the larger diameter of the blunt table will reduce the specific pressure on the contact surface of the buttons surface and the rock, especially when the rock is hard and the impact work is insufficient, the feed rate will be slowed down. To reduce the blunting and increase the feed rate under the condition of relatively soft rock, it is necessary to design the buttons shape to be sharper so that it has a higher specific pressure, which expands the effective amplitude of the stress wave, improves the impact capacity and makes it easier to chisel into the rock.

To sum up, choose the hemispherical buttons for hard rock. Choose the parabolic buttons or conical buttons for medium-hard or hard brittle rock. Sometimes, to make full use of the characteristics of alloy teeth, different tooth shapes are often used together.