Did you know magnetostrictive displacement sensors can also be applied in hydraulic rock drills?

As a type of rock drilling equipment, hydraulic rock drills are core machinery widely used in mining, tunnel excavation, water conservancy projects and other sectors, and constitute critical components of percussive drilling systems. Driven by high-pressure hydraulic oil, the piston strikes the drill rod at high frequency to break rock.

Figure 1: Hydraulic Rock Drill

As high-precision non-contact measuring equipment, magnetostrictive displacement sensors serve as critical components enabling intelligent and precise control of hydraulic rock drills and deliver core support for performance improvement of rock drills.

Hydraulic Rock Drills: Working Principle and Core Mechanisms

Working Principle and Characteristics of Hydraulic Rock Drills

Hydraulic rock drills operate mainly by utilizing hydraulic energy to drive percussion and rotation mechanisms. Precise control of impact force, rotational speed and thrust enables efficient rock breaking.

The percussion mechanism acts as the power core of the drill. Driven by an oil pump, hydraulic oil is alternately fed into the front and rear chambers of the piston cylinder via control valves. When pressure oil enters the rear chamber, it accelerates the piston forward to strike the shank with tremendous kinetic energy. Afterwards, the hydraulic circuit switches, and oil supplied to the front chamber pushes the piston back. This cycle repeats continuously to generate high-frequency impact.

The rotation mechanism is driven by a hydraulic motor, converting hydraulic energy into mechanical rotation to turn the drill rod. This allows the drill bit to contact different rock surfaces after each impact, realizing all-round rock fragmentation and forming neat circular boreholes.

The feed mechanism generates adjustable thrust via a hydraulic cylinder, steadily pushing the rock drill toward the rock face. This force ensures efficient transmission of impact energy to the rock. The thrust can also be adjusted in real time according to rock hardness to improve drilling efficiency and prevent drill jamming.

Precise coordination of these three mechanisms achieves efficient and controllable rock drilling.

Critical Role of Sensors in Hydraulic Rock Drills

Based on the working principle of hydraulic rock drills, precise control of piston stroke and drilling depth is essential during complex drilling operations, which directly affects construction quality and efficiency. As core measurement and control components, Zheda Jingyi magnetostrictive displacement sensors act as "precision eyes" for rock drills, playing two key roles:

On one hand, the sensor monitors displacement status of the hydraulic piston rod in real time. Mounted inside the hydraulic cylinder, it accurately captures tiny displacement of the piston rod based on the magnetostrictive effect by measuring the propagation time of magnetostrictive waves inside the waveguide wire. The electronic housing generates a current pulse that creates a magnetic field around the waveguide wire. Interaction with the magnetic field of the moving magnetic ring produces a strain wave. By calculating wave propagation time, the sensor obtains real-time downward and return position of the piston rod.

On the other hand, the sensor enables closed-loop control. Supported by accurate displacement data from magnetostrictive displacement sensors, modern intelligent rock drills can achieve efficient and reliable operation.