Shandong Taiheng Rotary Drilling Construction Hubei Rotary Drilling

Product Details

Selecting the drill pipe for a rotary drilling rig is a major subject

Selecting the drill pipe for a rotary drilling rig is no trivial matter; the model of the rotary drilling rig involves a great deal of knowledge and requires consideration of many geological factors. The first factor to consider is the geological condition (formation hardness). Formations from soft to hard are arranged as follows: silt layer; soil, (mud) sand layer; gravel (boulder) layer; strongly weathered rock layer; moderately weathered rock layer; weakly weathered rock layer; slightly weathered rock layer; bedrock layer.

 Having understood the geological conditions, one also needs to clarify the type of borehole. According to the different drilling pressure application methods used during drilling, drill pipes are divided into 3 types: friction pressure type drill pipe (referred to as friction pipe), mechanical locking pressure type drill pipe (referred to as mechanical locking pipe), and combined pressure type drill pipe (referred to as combined pipe).

Friction type drill pipe: When drilling in soft formations, the self-weight of the drill pipe and drilling tools can meet the requirements for feed pressure; in this case, a friction type drill pipe is sufficient. It can drill through silt layers, soil, (mud) sand layers, and gravel (boulder) layers.

 Mechanical locking type drill pipe: The mechanical locking type drill pipe can be used not only in soft formations but also in harder formations. It can drill through silt layers, soil, (mud) sand layers, gravel (boulder) layers, and strongly weathered rock layers.

What causes the hydraulic motor of a crawler rotary drilling rig to lack power?

 After a crawler rotary drilling rig has been used for a long period, operators will notice that the performance of the hydraulic system begins to deteriorate and is not as powerful as it was initially. Based on experience, the editor can tell just by looking at the wear degree of the valve plate that this is caused by the lack of power of the hydraulic motor of the rotary drilling rig.

The main causes of the lack of power of the hydraulic motor of a rotary drilling rig are as follows:

  1. Due to wear of the valve plate, the oil inlet and return passages are connected at the valve plate, part of the high-pressure oil leaks, the oil pressure flowing through the stator-rotor pair decreases, and the flow rate decreases, ultimately causing the output speed and torque of the motor to decrease.

　2. Due to wear of the valve plate, its relative position within the valve body changes, and the pre-tightening force and contact force between the valve plate and the valve disc provided by the spring in the valve body decrease, aggravating the leakage of hydraulic oil and causing the performance of the hydraulic motor to decline.

　3. The increase in hydraulic oil temperature causes its overall performance to decline, further reducing its ability to drive the cycloid rotor to rotate.

  4. Upon inspection, there is no obvious wear on the stator-rotor pair and the mating surfaces of the bearing housing and valve disc on both sides; movement is normal without sticking, and it will not cause performance decline.

 Now that the causes of the lack of power of the rotary drilling rig hydraulic motor are known, the next step is simply to clean the valve plate with compressed air.

The service life of a rotary drilling rig depends not only on its own quality but also on daily maintenance. Below, the editor analyzes common faults and handling methods of long spiral rotary drilling rigs, hoping to be of some help to you.

1. Inability to locate the pile position accurately. Since the long spiral drilling method rotates all the soil in the hole out to the surface, if not cleaned up in time, the positioning piles will be buried. Therefore, during the hole-forming process, the drilled soil must be cleaned up promptly, and then the positioned piles can be found according to the distance between piles.

2. Pile body inclination. Pile body inclination affects the bearing capacity of the pile, and at the same time, when ultrasonic testing is performed on the pile body, it is easy to measure it as a short pile. Measures: To ensure the verticality of the pile, mainly control the verticality of the drill pipe of the drilling rig. Install one plumb bob or pointer on the front and side of the front column of the drilling rig, attach a reflective film with scale, and draw scale lines on the reflective film to indicate the maximum deviation of the pointer or plumb bob. When the scale line is exceeded, adjust the outriggers of the drilling rig until the pointer or plumb bob falls within the scale line.

3. Drilling process control. CFG piles are controlled according to the design pile length, with the instantaneous current value as an auxiliary control. When the drill bit passes through each soil layer, the current changes instantaneously; the drilling current differs for different soil layers. If, upon reaching the design pile length, the current value shows a decreasing trend, the bearing capacity σ value of the soil layer becomes smaller; in this case, design and other relevant personnel must be contacted to solve the problem on site.

4. Pipe blockage. The workability of the mixture directly affects the pumping of the mixture and can easily cause pipe blockage, resulting in broken piles; in addition, on-site operation and mechanical equipment can also cause pipe blockage. Control measures: ① Before mixing and transporting the mixture, the crushed stone and