-
-
-
-
Honor
-
-
-
-
-
Contact
-
Precautions for the use of drilling tools-YiKuang Technology
Release time:
2020-03-03
Author:
Source:
The drill rod is limited by the diameter of the drilling hole in the drilling and blasting project, and its cross-sectional area is very small. This slender rod should bear the cyclic stress of pulling, pressing, bending and twisting applied by the rock drill with high frequency and high impact under the condition of severe wear and corrosive medium. According to the different conditions such as load size and rock firmness, the rock drilling life is often only more than ten hours to more than one hundred hours. It is an engineering tool with the most demanding stress conditions, short service life, high technical content and huge consumption necessary for basic industries among all human mechanical tools.
As every drill user wants to spend the least cost to get the most profit, which requires reducing the loss of the drill, so the drill producers and users should work closely together to discuss, in order to improve the service life of the drill joint advice.
1, from the user's point of view, the choice of brazing products should have the following characteristics:
(1) High-quality brazing products: The brazing products are usually required to have a high life span to reduce the time for disassembling and replacing the brazing tail. The requirements for drill rods and drill bits are also quite high, because the drill rod will not only lose the drill rod and drill bit, but also cause waste holes. Due to the high degree of automation of the hydraulic rock drilling rig, the operator does not need to pay a lot of labor intensity in normal production, and the dismantling of the machine to replace the drill tail, salvage the broken drill rod or grinding the drill head, not only a waste of working hours, but also increased the labor intensity and labor costs of the operator. Therefore, users in the choice of drilling products, attention is not only the price of the product, more attention is the quality of the product.
(2) the best drilling rate: in the trolley operation, in addition to the cost of labor compensation and the purchase of drilling tools, other man-hour costs are regarded as fixed costs, and the cost of drilling tools in the drilling operation is very high, therefore, improve the drilling speed means to reduce the construction cost, so the user attaches great importance to improve the drilling speed.
(3) the minimum hole deviation: in the middle and deep hole drilling blasting, the hole deviation means that the amount of charge is reduced and the hole spacing is shortened, which also leads to the reduction of the amount of mining. Therefore, the user has high requirements on the straightness of the hole, which is usually controlled within a small error range. The main causes of blast hole deflection are hole error during drilling, hole calibration error and straightness error during drilling. The first two errors can be basically eliminated in full hydraulic drilling rig or computer-controlled hydraulic drilling rig. However, the blast hole deflection caused by the structure of drilling rig becomes the main reason. With the deepening of drilling depth, the deflection degree will increase and eventually lead to waste holes, the best way to reduce or eliminate blast hole deflection is to use guided drilling tools.
2. Cause analysis of drilling tool loss
(1) The drilling tool group is not concentric
The non-concentricity among the drill tail, the connecting sleeve and the drill pipe causes the bending deformation of the drill tool and generates stress, resulting in the non-matching of the joint of the drill tool group and the loosening of the joint part.
(2) Propulsion pressure
If the pressure is too low, the drilling penetration efficiency will be reduced, causing the combination to loosen, causing the energy loss transmitted by the drilling tool group, causing great stress, resulting in instantaneous contact and separation of the contact joint end face. Insufficient pushing pressure is manifested by heating of the drilling tool, "clatter" at the joint, excessive heat causing excessive thread wear and corrosion pits. The pressure is too high, the drill bit rotation speed is low, there is a danger of sticking, and the bending stress of the drill pipe increases.
(3) Impact pressure
If the impact pressure is not adjusted properly, it will directly affect the rotation speed, the efficiency of the rotary drilling and the life of the drilling tool.
(4) Rotation speed
The slewing speed should match the drill diameter and the impact frequency of the rock drill. The larger the drill bit, the lower the rotation speed, and the high rotation speed will damage the periphery of the drill bit.
(5) Swing pressure
Normal rotary pressure is very important, it can not only provide proper anti-card protection for the drill pipe, but also ensure a certain rotary pressure. The increment of rotary pressure is the key factor to keep the tightness of the brazing tool group. Insufficient tightness often causes heating of the connecting part, peeling of the thread surface, early wear of the thread and even fracture of the thread.
(6) improper use method
After the use of the drilling tool combination, if used in conjunction with the new drilling tool will shorten the service life of the drilling tool, in addition, the rod is not aligned, there is sand on the thread, the thread connection without lubricating oil is also easy to damage the drilling tool. "Empty hitting" is the most serious damage to drilling tools and should be avoided as far as possible.
3. Relationship between drilling parameters and drilling effect:
Impact pressure: The higher the pressure, the higher the piston speed and the greater the energy generated. When the drill bit is in good contact with the complete hard rock, the shock wave energy can be maximized. On the contrary, when the contact between the drill bit and the rock is not good, the energy cannot leave the drilling tool and be transmitted to the rock, but is reflected back to the drilling tool chain as a tension wave. Only when drilling holes in sufficiently hard rock can the maximum energy of each impact be used. In order to reduce energy reflection when drilling soft rock, the impact pressure or energy must be reduced. The greater any given impact pressure, the greater the stress in the drill pipe section. In order to make the service life of the drill rod and drill tail as long as possible, it must be ensured that the working pressure must match the drilling tool chain at any time.
Propulsion pressure: The purpose of propulsion is to make the drill bit and rock close contact, while the drill bit can also turn. The propulsion force must be reasonably matched with the impact pressure. The correct propulsion force can make drilling the most economical; the low propulsion pressure will reduce the penetration speed and loosen the threaded connection part of the drilling tool; the overheating of the connecting sleeve and the rattling noise indicate the too low propulsion pressure setting; if the connection part is loose and continues to drill, the energy loss will increase and the temperature of the connecting sleeve will be too high, resulting in ablation and fracture of the threaded connection part of the drilling tool; if the propulsion force is too large, the rotating speed will decrease, the penetration rate is also reduced and there is a risk of sticking; in addition, there is a risk of deflection of the drill hole, because the thrust force is too high and the drill chain tends to bend.
Rotation speed: The purpose of rotation is to turn the drill bit to a new position for the next impact. When using a column tooth drill, the circumference between two impacts is about 10mm. Therefore, the rotation speed must be adjusted according to the impact frequency and the change of the drill diameter. The larger the diameter of the drill bit, the lower the speed should be. Excessive rotational speed will cause excessive wear of the bit teeth.
4, in the process of using the drill, should pay attention to the following points:
(1) Before entering the rod, adjust the appropriate impact pressure, propulsion pressure, rotation speed and buffer pressure according to different geological strata, and debug the pressure values to match the geological strata and rock hardness between the pressure values.
(2) When drilling, make the drilling tool group concentric to avoid bending deformation of the drill tail, drill rod and drill head.
(3) Avoid empty hitting, stop drilling immediately when empty hitting occurs, and avoid causing excessive damage to drilling tools.
(4) After drilling the drill rod, each drill rod withdrawn should be coated with cooling lubricating oil in the thread end and quick joint of the drill rod-after the drilling operation is completed, the thread connection of the drill rod is high temperature and there are some gravel blocks and mineral water, and the coating of cooling oil plays the role of lubrication, cooling, corrosion prevention and improvement of thread wear resistance.
(5) In the process of rod withdrawal, try to avoid repeated rod vibration (this operation is one of the reasons for the biggest damage to the drill rod). When the thread connection of the drill rod is difficult to loosen, inject lubricating oil into the thread at the first time, and then withdraw the rod or loosen the vibrating rod, so as to reduce the direct damage to the thread of the drill rod during the vibrating rod-when the rod is vibrating rod, the rock drill will transmit an impact pressure of nearly 200bar. Under the continuous action of high-frequency impact pressure, stress concentration will be caused. Repeated vibration will lead to high temperature and high heat, which will cause cold solder joint burning at the threaded end of the drill rod, I .e. ablation pit, and even form a melting pit at the melting temperature of the metal, thus forming a fatigue source and causing early failure of the drill rod.
Key words:
