About the classification and application of rotary drilling rigs

How much do you know about rotary drilling rigs? Many people think that rotary drilling rigs have a larger diameter and deeper drilling than traditional circulation drilling rigs. In fact, this is a misunderstanding. Do you know how many classifications of rotary drilling rigs and in which fields are they used?

Generally, the suitable drilling depth for rotary drilling rigs is within 50-60m, and the drilling diameter is within 2m, most of which are within 1.8m; while the drilling depth of domestic reverse circulation drilling rigs can reach hundreds of meters, and the drilling diameter They are all at 3m. Rotary drilling rigs can hardly do this. This is determined by the structure of the rig. Rotary drilling rigs rely on telescopic drill rods for soil extraction. When the hole depth increases, longer drill rods must be used, and longer drill rods will inevitably increase the weight of the drill rods. Considering the balance of the whole machine, the equipment cost will increase. In addition, if the drilling depth is too large, the drilling time in the hole will be much less than the auxiliary time such as lifting and unloading the soil, which will greatly reduce the work efficiency. Although the drilling depth and diameter of rotary drilling rigs have no advantages over circulating drilling rigs, they have absolute advantages in terms of ergonomics, environmental protection, displacement, and especially stratum adaptability. These characteristics can solve the most common problems in foundation construction. problem.

Precautions for choosing a rotary drilling rig

At present, there are many types of rotary drilling rigs on the market in our country, and the prices are relatively expensive. If you want to buy a model with ideal performance and price, suitable for your own market development needs, you should focus on the following issues when selecting models. ①According to the field of pile foundations constructed by the enterprise, select models with suitable drilling capacity; ②For products of the same level from different manufacturers, focus on comparing the three parameters of the rated rotation torque of the power head, the lifting force of the main winch single rope, and the weight of the machine. Choose the larger model of the three; ③Carefully analyze the performance-price ratio of the drilling rig; ④Try to choose a manufacturer with good after-sales service; ⑤Know the manufacturer’s rated output torque of the power head, rated working pressure of the hydraulic system, safety factor of the main winch, etc. An important number to measure the actual capacity and working reliability of a drilling rig. After determining the size of the model, the following items should be considered when purchasing a rotary drilling rig.

1. Rig torque

The torque of the drilling rig is selected according to the engineering needs to ensure that the drilling rig can work reliably in the high area of ​​the drilling rig. The high-efficiency zone of the drilling rig generally refers to the average progress of the drilling rig being above 5m/h during normal drilling. For example, using short auger bits and barrel drill bits, the hole diameter in the soil layer is 800mm, the drill should have a torque of 80kNm, and the hole diameter should be increased by 10kNm every time the diameter of the hole is enlarged by 100mm. In dense sand and gravel houses, the drill torque should be increased by 15-20kNm for every 100mm increase in the hole diameter. It must be pointed out that the drilling speed is closely related to the structure and structural parameters of the drill bit.

2. Drill pipe

The drill rod must transmit the full torque of the power head to the drill bit at the bottom of the hole, and also stably transmit the pressure of the pressurized hydraulic cylinder, the weight of the power head and the weight of the drill rod to the drill bit below tens of meters. When drilling into harder formations, the drill pipe has to withstand high torque and heavy weight on bit at the same time, and it must overcome a large bending moment. If the drill pipe fails to meet the requirements, it will be easily damaged.

The pressurization method adopted by the drilling rigs of various manufacturers is mainly reflected in the form of the drill pipe. The friction-type telescopic drill pipe has higher drilling efficiency in soft soil; the machine-locked drill pipe is suitable for drilling into hard rock formations, and the operation is correct. The requirement of high pressure is higher, it is necessary to find a pressure point for pressure; self-locking armored drill pipe can be pressurized at any time, and the torque transmission effect is good. Kay type drill pipes can be divided into two categories: friction drill pipes and locking drill pipes. At present, in terms of drill rod form, drill rods can be divided into wedge type, half-tooth wedge type, and friction type in large order. The wedge type and half-tooth wedge type can reliably achieve drill pipe compression when drilling holes in hard formations, and when drilling holes in hard formations and general formations. The controllability of the pressure of the drill pipe is very good.

The length of the drill pipe should be determined according to the depth of the hole. When the depth of the hole is large, two sets of drill pipes should be selected, one set of long drill pipe no less than 60m and one set of short drill pipe about 40m. In order to ensure the installation of the drill bit with the largest diameter, the distance between the centerline of the drill pipe of the medium and small rig and the chute surface of the drill mast should be no less than 1m, and the distance between the large rig should be no less than 1.2m. Drill pipe vibration damping. Rubber vibration damping only has the function of damping, which can reduce the wear of the end of each drill pipe and ensure the service life of the drill pipe. Spring vibration damping and rubber-spring composite vibration damping not only effectively ensure the service life of the drill pipe, but also can remove the hard-to-remove clay-like slag in the drill bit through vibration to improve work efficiency. For drill pipes with spring damping, the service life of the spring is shorter when the vibration unloading method is adopted. The vibration amplitude and number of vibrations should be strictly controlled, and spare springs should be provided. It is recommended that the short drill pipe use spring to reduce vibration, and the long drill pipe use rubber to reduce vibration.

3. Drill mast adjustment structure

Currently, there are two types of drill mast adjustment structures: triangle and parallel four sides, each with its own advantages. In the construction site, from the perspective of the on-site installation and disassembly of the drilling rig and the crossing of air obstacles during the construction, the parallelogram-shaped drill mast adjustment structure is more practical.

4. Auxiliary system

1) The external rotary drilling rig should be equipped with an automatic depth sounding device, which can measure the depth of each drilling and the total drilling depth. This is indispensable for the quality and safe operation of drilling rigs.

2) The drilling rig should also be equipped with a vertical deviation correction device, with automatic and manual methods, so as to adjust and correct the vertical state of the drill pipe at any time and quickly to ensure the quality of the hole.

3) The safety devices of the drilling rig include emergency stop and cab protection devices. The emergency stop device mainly prevents accidents such as the drill rig hurting people in the blind area of ​​the driver's eyesight when the rig is working.

4) Each part of the drilling rig has space for repair and maintenance, the parts are easy to replace, and the special tools and general tools equipped with the drilling rig are complete and durable.

5. Other matters

The power system requires reliable work and long trouble-free working hours. Generally, famous-brand engines with domestic spare parts should be used; hydraulic and electrical systems require reliable performance, and domestic spare parts should be resolved; the transportation size of the drilling rig should be controlled to a maximum length of about 13m, a width of 3.2m or less, and a height of 3.2m or less.

Each manufacturer’s drilling rig has its own advantages in terms of performance and price. The hole diameter of each manufacturer’s leading product is the maximum drilling diameter between 1-3m, providing users with a wide range of options. In summary, each type of drilling rig has its own different advantages. Some are relatively cheap, some are more automated but have the same requirements for operation, and some have excellent performance but are more expensive. According to their own financial situation and common engineering situation, the user comprehensively considers the cost performance, and chooses drilling rigs with different prices and different performance advantages.