Correct and reasonable use of rock drilling tools

1. Improving the design quality, determining reasonable structural parameters, and continuously developing new varieties are the prerequisites for improving the life of the drill. The crown shape of the column teeth of the column tooth drill bit is mostly hemispherical, the rock drilling speed is high, and when pressed into the rock, the tooth surface is subjected to compressive stress and is relatively strong and durable. The size of the tooth diameter should consider sufficient tensile stress resistance and solid tooth strength. From the failure analysis, the stress condition of the side teeth is poor, and the side teeth are stripped and broken. The main forms of damage to the drill bit. The following measures can be taken to reduce the damage to the side teeth and extend the service life of the column tooth drill bit: ① Strengthen the side teeth, correctly select the tooth shape, tooth diameter and tooth height; ② Appropriately reduce the inclination angle of the side teeth, which is conducive to improving the stress condition and improving the impact resistance of the side teeth; ③ Correctly select the weld gap and the interference of the solid teeth to increase the fixing force of the column teeth; ④ The side teeth are selected from cemented carbide with high toughness, and heat treated to prevent tooth breakage. Strengthen the steel body of the drill bit and increase the abrasion resistance of the steel body; ⑤ Rationally arrange the teeth, increase the number of side teeth as much as possible, improve the powder discharge system, retain the front water hole and the large gap three grooves and two holes powder discharge system, high powder discharge efficiency, reduce the repeated crushing of rock powder, reduce energy consumption, and extend the service life of the drill bit.

Improve the structure of the drill rod, such as the American Ingersoll Rand-Rand Company proposed a full-threaded drill rod, which is processed by rolling forming and surface hardening to improve toughness and wear resistance, with a large helix angle, good self-locking, and easy disassembly and assembly. Improving the appearance quality and packaging quality of the drill tool, designing the appearance shape and packaging structure can effectively protect the drill tool, beautify the drill tool, and extend the service life of the drill tool.

2. Select high-quality materials. The selection of drill tools should consider toughness, wear resistance, good rigidity and wear resistance, sufficiently high fatigue strength, low fatigue notch sensitivity, high ability to clamp alloy sheets, and certain corrosion resistance: ①24SiMnNi2CrMo steel is a new steel type that imitates Swedish FF710 steel and has the best comprehensive evaluation of conventional mechanical properties and fracture properties; ②The average cumulative footage of drill rods made of 40SiMnMoV steel is 1225.4m, close to the foreign level; ③The life of small drill rods made of 55SiMnMo is close to the 250m level of Swedish 95CrMo small drill rods; ④The average life of drill rods made of 35SiMnMoV can reach 300m/root. The above steels are heat treated by quenching, tempering, annealing, normalizing, etc. to form bainitic steel with high fatigue strength and toughness. For induction brazing fixed sheets and fixed teeth small and medium-sized drill bits, 40MnMoV is selected as the drill bit body material; for hot-embedded fixed teeth drill bits, 45NiCrMoV steel is preferred. The selection of cemented carbide materials must be adapted to the mechanical properties of the rock and the type of rock drill.

3 Advanced manufacturing technology should be used to produce drill bits by cutting method, and full mechanical processing should be realized to replace the traditional old forging molding, which is a new development of drill tool manufacturing technology. The brazing of blade drill bits must use good heating equipment such as ultrasonic frequency. The medium frequency electric furnace can be used for overall induction heating to prevent the workpiece from oxidation and decarburization. The temperature is easy to control, the heating time is short, and the brazing operation is convenient. Strictly control air cooling or air cooling to prevent welding stress. Appropriately increase the weld seam, select grinding discs in grades, and use gasoline and other organic solvents to carefully clean the welding surface of the drill bit body steel and cemented carbide sheet to improve the brazing quality.

For large and medium diameters, the hot embedded tooth process should be promoted. It has little effect on the performance of the drill bit body and cemented carbide, the surface of the teeth and holes is not easy to damage and the quality is stable. After the teeth and holes are assembled, the bonding surface is in a two-dimensional stress state, the solid teeth have good quality, and the broken teeth are reduced. The best heat treatment specifications of the steel body can be achieved, and the use potential of steel can be fully utilized. There is no welding liquid flowing and the appearance quality is good. Cold pressed teeth require high hole processing accuracy, and high-precision processing equipment is often used. The tool design uses the shortest size chain to enhance contact stiffness and improve the surface quality of the tooth hole. In the tool design, the tool structure that increases the cutting deformation geometry and extrusion strengthens the processing surface is selected, and the residual compressive stress and cold-work hardened metamorphic layer are formed on the hole wall surface by strong cutting. To increase the service life of the drill rod, it is necessary to manufacture precise processing and making molds to prevent the forging from producing flares, flashes, and cracks. Improve the rolling quality of hollow steel and eliminate or reduce various surface defects such as dents, scars, folds, and decarburization.