1, small rotary drilling rig into the rock encountered problems small rotary drilling rig into the rock has been the following three technical difficulties:

(1) Light weight itself;

(2) Small axial pressure;

(3) The rock impact on the rotary drilling rig itself is large.

Due to the lack of axial pressure of rotary drilling rigs, it is difficult to realize efficient rock crushing "leapfrog crushing" in the form of its main reasons are two aspects:

(1) small rotary drilling rig itself weight is small, not only to ensure the mobility and flexibility of small and medium-sized rotary drilling rigs, but also to ensure that their own weight can withstand the impact of the reaction of the rock, and at the same time to ensure their own safety and stability, so that small and medium-sized drilling rigs seems to be a challenge. The design of the drilling rig, as well as the appropriate construction method, puts a new demand on the rotary drilling rig designer. The rotary drilling rig manufacturer's method of construction is to use a cylinder drill, which utilizes grinding or fatigue damage of the cut-off teeth, and then is equipped with special tools to break the core and remove the core intact with the cylinder drill.

(2) Rock is an anisotropic, inhomogeneous, discontinuous tissue, complex geological conditions, and is located in the deep underground depths;

2, into the rock construction rotary drilling rig pressurization construction method mainly adopts the "constant pressure and point dynamic pressure combined way", constant pressure is mainly to produce static load, to provide constant pressure for grinding rock, point dynamic pressure is mainly to form a certain impact on the rock, to achieve the local crushing of the rock, the two ways of pressure combined with each other to achieve the rapid cutting of rock. Rapid cutting of rock. Due to the uneven hardness and softness of the rock, the rotational speed will change with the load, resulting in alternating fast and slow in the process of drilling, which also causes a certain impact on the rock, thus accelerating the role of rock cutting. In addition, in the process of drilling to continuously produce water or mud, mainly to play a role in lubrication and cooling the role of the drilling bucket, to reduce the rotary drill bit because of the heat caused by the damage to the equipment.

3, core removal when the use of cylinder drilling to reach the specified requirements, the need to cut off the rock and take out. Because of the light weight of the small drilling rig itself and the torque is small, can not directly cut off the rock, which requires a special wedge bucket, the use of wedge pressurization principle, the wedge bucket pressure F generated by the core of the radial force F1, and ultimately break the rock.

4, the rock into the rock mechanism analysis of small rotary drilling rig can be successful fast into the rock, mainly due to the rig itself is designed to strictly comply with the European Union's EN791 safety design standards, in full consideration of the rotary drilling rig safety, stability, based on the weight of the whole machine for a reasonable distribution, and then to achieve its flexibility, the reliable design of the structure can withstand the reaction force of the lock rod of the small machine, so as to achieve a larger The reliable design structure can withstand the reaction force of the locking bar of the small machine, so as to realize the larger pressure transmission and higher rock penetration efficiency, and achieve the optimal result. The small-sized rotary drilling rig gives full consideration to the three stages of rock crushing mechanism: grinding crushing section, fatigue crushing section and leaping crushing section.

(1) Grinding and crushing section: under the action of small shaft pressure, the contact pressure generated by the contact between the drill bucket and the rock is significantly less than the ultimate strength of the rock or the hardness of the indentation, and the crushing is based on the friction cutting, and the crushed particles at this stage are small, and there is a certain degree of wear on the drill bit.

(2) Fatigue crushing section: when the pressure load increases to a certain value, still not reached the ultimate strength of the rock or the hardness of the indentation, the rotary drill bit many times with the rock impact contact, making the rock produce micro-cracks, micro-cracks, the more the strength of the rock will be reduced to a certain extent, when the strength of the rock is reduced to a certain degree, after the drill bit many times impact the rock will form a large particle of the rock debris, thus forming the fatigue Crushing. (3) Leapfrog crushing section: under sufficient axial pressure, the contact pressure between the drill bit and the rock is greater than or equal to the ultimate strength of the rock or the hardness of the indentation, then the rock produces leapfrog crushing. The particles of leapfrog crushing are relatively large. The rock crushing mechanism of rotary drilling rig into the rock is to utilize the grinding crushing section and fatigue crushing section. It solves the problem that small and medium-sized rotary drilling rigs are light in weight and provide small axial pressure, and achieves a reasonable value in pressurization and rotational speed of the power head, while maintaining the advantages of mobility and flexibility of small and medium-sized drilling rigs. In the problem of removing the core, an effective and reasonable method is adopted, as well as suitable drilling tools, and the complete core is successfully removed.

5 Conclusion:

(1) Utilizing the crushing mechanism of rock, adjusting the design of the rotary drilling rig and equipping it with suitable drilling tools makes it completely feasible for the rotary drilling rig to enter the rock, and it is fully demonstrated in practice. The problem that small and medium-sized rotary drilling rigs cannot enter the rock is solved.

(2) Small drilling rigs, due to their own light weight, to realize rock penetration must use the machine locking bar to transfer the weight of the whole machine to the working surface, but the larger reaction force puts forward higher requirements for the reliability of the rotary drilling rig structure.

(3) Drilling in the rock, must be equipped with appropriate drilling tools, especially to take out the core of this problem, must be equipped with appropriate tools, so the research in the drilling tools is also essential, and will be our future rotary drilling rig into the rock of the research of a large direction.

(4) The research on the working method of rotary drilling rig is even more essential, such as the reasonable distribution of pressure and the relationship between the rotational speed of the power head, the rock drilling must be injected with water or mud, the drilling tools to cool down and increase the lubrication.

(5) The small rotary drilling rig is especially important because of its own weight limitations, under the condition of ensuring stability, the reasonable allocation of the proportion of drilling pipe, drilling tools, mast and the total weight of the drilling rig, and at the same time can play the small rotary drilling rig performance in the most prominent features of high flexibility and low fuel consumption.