Relationship between Rock Drilling Parameters of Drill Jumbo and Rock Drilling Efficiency

Table of Contents

In rock engineering, drill jumbos are widely used in drilling, rock drilling, and other operations, and the rock drilling efficiency is directly related to the quality and progress of the project. The rock-drilling efficiency of the drill jumbo is affected by various parameters. Discussing the relationship between the rock-drilling parameters of the drill jumbo and the rock-drilling efficiency can help us optimize the engineering rock-drilling operation and improve work efficiency and effect.

The rock drilling parameters of the drill jumbo include drill bit type, drill bit diameter, impact pressure, propulsion pressure, rotation speed, etc. These parameters affect each other and jointly determine the effect of rock drilling.

Types and Diameters of Rock Drill Bits

rock drill bits

The type of rock drill bit is selected according to the rock hardness. Different types of rock drill bits are suitable for rocks of various hardness, and the diameter of the drill bit affects the area of a single rock drilling, and the larger diameter drill bit can break the rock faster. Choosing the right drill bit type and diameter can significantly affect rock drilling results.

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 intact hard rock, it will maximize the use of shockwave energy. Conversely, when the drill bit is in poor contact with the rock, the shock wave energy is not transferred to the rock but is reflected to the toolchain as a tension wave. The maximum energy per impact is only harnessed when drilling in sufficiently hard rock. To minimize energy reflection when drilling soft rock, the impact pressure must be reduced. The greater the pressure for any given impact, the greater the stress in the drill rod section. To prolong the service life of drill rods and shank adapters, it is necessary to ensure that the working pressure matches the drill chain at any time.

Pushing pressure

Propulsion is required to make the drill bit closely in contact with the rock and to complete the drill bit rotation. The propulsion force should be properly matched to the impact pressure. The correct propulsion force allows for the most economical drilling; too low a propulsion pressure reduces the penetration rate and loosens the threaded joints of the rock drilling tool; overheating and rattling noises from the coupling sleeve indicate a propulsion pressure setting that is too low; if drilling is to continue with a loosened coupling, there will be an increase in the energy loss and the coupling sleeve will become too hot, which will result in corrosion and fracture of rock drilling tool threaded couplings; if the propulsion force is too large, the rotation speed will decrease, the penetration rate will decrease, reduce and bring the risk of drill sticking; in addition, there is a risk of drilling deflection, because the driving force is too large, and at the same time, the toolchain has a tendency to bend.

Rotary speed

The purpose of the rotation is to turn the drill bit to a new position for the following impact. The rotational speed should be adjusted according to the impact frequency and the change in the drill bit diameter;  larger the drill bit diameter, the lower the rotational speed. Too high speed will cause excessive wear of the gauge button.

There is a close relationship between the rock drilling parameters of the drill jumbo and the rock drilling efficiency. Reasonable selection and adjustment of rock drilling parameters of drill jumbo can realize more efficient and economical rock drilling operation. In practice, the operator needs to comprehensively consider the influence of various parameters according to the characteristics of different rocks and engineering requirements to achieve the best rock drilling efficiency. Through in-depth research and practice, manufacturers can continuously optimize the rock drilling operation of drill jumbos and improve the overall level of rock engineering.

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