The DTH drill bit is a rock drilling tool used in large-scale open-pit mines, underground ore mining, anchoring engineering, quarrying rock drilling, construction engineering rock drilling, and large-scale engineering construction. Many factors affect the efficiency and cost of down-the-hole rock drilling operations, but if you want to obtain higher rock drilling speed and lower perforation cost, it is very important to choose a suitable drill bit and use it reasonably. So how to choose the right drill bit and use it reasonably?
Although external factors such as rock properties need to be considered when selecting a suitable DTH drill bit, internal factors such as structural design, material selection, and heat treatment requirements directly affect its service life, so these also need to be paid attention to.
Structural design
1. From the working principle of the DTH hammer and the working condition of the drill bit, to improve the rock drilling efficiency and service life, the structure of the drill bit should reduce the power consumption of rock drilling, smooth slag discharge, reduce repeated crushing, and minimize the stress on the drill bit.
2. The length and weight of the drill bit are closely related to the length and weight of the piston. According to the theory of wave dynamics, the weight of the two should be similar to obtain a good stress state and better energy transfer efficiency to achieve a lower gouging work ratio consumption effect.
3. Because of the harsh working conditions of the gauge button and the high linear speed of movement, the number of teeth should be increased appropriately to prevent the drill from sticking.
4. Vent holes and slag discharge grooves should be able to effectively cool the drill bit and clean the rock powder at the bottom of the hole.
5. Spline structure is adopted at the end of the drill bit, which transmits high torque and even force.
Material selection
In order not to cause fatigue fracture, there must be a certain fracture strength. In order not to cause a brittle fracture, there should be a certain fracture toughness. You can choose 35SiMnCrNiMoV, 45CrNiMoV, and other steel grades.
Heat treatment requirements
Heat treatment is a key factor to ensure the quality of drill bits. Practice shows that improving the strength and toughness of the drill bit body at the same time is a prerequisite for realizing the technological design of the button bit. The following measures are generally adopted for the manufacture and processing of the drill bit body: replace the conventional split hardening process with heat treatment overall quenching so that the hardness of the drill bit body is the same from the head to the tail and slightly lower at the head, and the drill dumpling process is used for the drill body exhaust hole to improve its surface roughness, improve the hardening of the inner hole, eliminate the occurrence of heat treatment cracks, ensure the quality of the drill bit body and improve its service life.
Tooth fixing process
The fixed tooth process adopts tooth grinding, hole reaming, and interference cold pressing solid tooth technology. The tooth hole is drilled and reamed after hardening to improve the precision of the tooth hole and eliminate the phenomenon of tooth hole ellipse, taper, and bell mouth.
Selection of head shape
There are three types of DTH drill bit head shapes convex, flat, and concave. The convex drill bit in the middle has a high drilling speed, good balance, and long service life, especially suitable for hard and highly abrasive rocks; the flat drill is especially suitable for cracks with cracks and rock formations with changing rock properties; When the concave drill bit is drilling, the protruding rock core can play a guiding and centering role. Like an inverted guide, it can form a straight hole with good performance and can offset the force directed to the center of the drill bit, which can reduce the drill bit accordingly. Rotary torque is especially suitable for deep-hole drilling.
Carbide buttons are available in semi-circular, slug, semi-slug, and conical shapes. Semi-circular is durable and efficient, especially suitable for very hard and corrosion-resistant rocks and deep-hole rock drilling; slug-shaped is suitable for soft, medium-soft, low abrasive rocks, and produces large slag particles, not suitable for rocks with large cracks; semi-slug shape, conical shape is suitable for all soft and medium soft rocks, including cracked rocks.
How to use the DTH drill bit reasonably?
Although the internal quality of the DTH drill bit is inseparable from its service life, its correct use can also prolong its service life and save perforation costs. Therefore, pay attention to the following aspects:
1. Avoid heavy impact under light pressure. Otherwise, excessive tensile stress will be generated in the drill bit body, which will easily cause the column button to fall off.
2. Avoid pure rotary under heavy pressure. Otherwise, it will accelerate the wear of the drill gauge button.
3. The drill rig is installed firmly to avoid swinging.
4. The bent drill pipe must be replaced in time.
5. The column button of the drill bit must be ground immediately. According to relevant standards, when the diameter of the abrasive surface of the column button reaches 1/2 of the diameter of the column button, it must be reground.
