Overview of Hydraulic Rock Breaker Theoretical Research

1.5 Overview of Hydraulic Rock Breaker Theoretical Research

During hydraulic rock breaker operation, the working chamber oil pressure switches at high frequency under control of the directional valve; the characteristics of the fluid in the oil passage cannot be simply discussed according to hydraulic transmission theory, and hydraulic vibration theory analysis must be applied. The force acting on the piston and chisel rises from zero to tens to hundreds of megapascals within a few tens of microseconds, then drops back to zero; the form of energy transmission by stress waves determines that work process description cannot simply use statics, rigid body mechanics, and kinematics theory. The impact machine principle belongs to elastic body dynamics problems and wave theory must be used to accurately describe its energy transmission process.

Based on the differences in basic assumptions and mathematical models, hydraulic rock breaker research falls into two major categories: linear model research and nonlinear model research.

1.5.1 Linear Research Models for Hydraulic Rock Breakers

Linear research is idealised research conducted by linearising non-linear hydraulic rock breakers through assumptions — linear models obtained under the assumption of 'constant hydraulic oil pressure' and ignoring certain factors. Its research premise is the view proposed by Soviet-era scholars OdAlimov and SAbasov in 'Hydraulic Vibration Impact Machine Structure Theory': 'Under the condition of guaranteeing a given impact end velocity, pressure-fully-equal pressure control is the optimal control with the highest efficiency.' On the basis of the 'constant pressure control' assumption, Soviet-era scholars proposed the optimal design scheme for minimum peak thrust force. Japanese scholar Nakamai et al., on this basis considering pipeline resistance, conducted theoretical and design research on the adjustability of piston stroke. Professor Li Dazhi of Beijing University of Science and Technology proposed the idea of optimal stroke design. Chen Yufan et al. used linear models of impact devices, employing dimensionless analysis with the optimal stroke method, to carry out dimensionless analysis of impact device parameters, obtaining a series of parameter relational expressions for guiding design work. Teacher Chen Dingyuan of Beijing University of Science and Technology, using C = S/S_m (S: operating stroke, S_m: maximum stroke) as the design variable, conducted dimensionless analysis of hydraulic rock breakers and obtained that the optimal efficiency zone is C = 0.75 to 0.850. Teacher Wang Zheng of Beijing University of Science and Technology, using the time t of piston return acceleration as the design variable, conducted comprehensive parameter analysis and obtained: when accumulator volume change is minimum, t = 0.406T; when the hydraulic impact is minimum, t = 0.5T. Teacher He Qinghua of Central South University used the impact device structural characteristic coefficient — piston front-rear chamber effective area ratio — as the dimensionless design variable to carry out optimisation design on impact devices. Because many linear studies have not considered the mutual restraint relationship between piston and valve that directly affects impact performance and the state of the accumulator, they cannot accurately reflect the interrelationships among the many structural parameters in the mechanism. Although their research precision is relatively poor, their results can basically reflect the influence relationship of various factors on performance, and therefore have a certain practical value in theoretical and design research.

1.5.2 Nonlinear Models for Hydraulic Rock Breakers

As a relatively typical and complex single-body mechanical feedback tracking system, the hydraulic rock breaker, like nonlinear systems in other fields, has many nonlinear phenomena and patterns. Nonlinear research has more comprehensively considered the influencing factors of hydraulic rock breaker motion, relatively comprehensively analysed the stress state of the hydraulic rock breaker, and obtained high-order nonlinear differential equation sets to describe its motion patterns. But the equations are difficult to solve, the description is not intuitive, and can only be solved numerically through computers. In recent years, with the development of computer science and technology and the popularisation of microcomputers, research on nonlinear mathematical models has received increasing attention from people.

As early as the early 1970s, foreign scholars applied digital computers to impact machine simulation research on pneumatic rock drills, obtaining relatively accurate results. In 1976, Japanese scholar Masao Masabuchi was the earliest to use mathematical computation to study hydraulic rock breakers, proposing a mathematical model for a hydraulic impact test device and using iterative computation to find power stroke velocity and frequency, then comparing with measured values. In the 1980s, Japanese scholars Takauchi Yoshio, Tanimata Shu et al. conducted nonlinear research on hydraulic rock breaker performance and design, proposing analytical models suitable for hydraulic rock breaker performance evaluation and design, and the derivation theory and analysis method for the analytical model. In 1980, Li Dazhi and Chen Dingyuan of Beijing University of Science and Technology proposed a nonlinear mathematical model using accumulator pressure as working pressure, and sought stable numerical solutions. In 1983, He Qinghua of Central South Industrial University, in 'Hydraulic Rock Breaker Numerical Simulation Research', used the state switching method to establish a comprehensive mathematical model, proposed the 'Quasi-uniform acceleration calculation method' (PUA method), corrected errors at state transition points, and improved simulation accuracy. In 1987, Professor Chen Xiaozhong and Teacher Chen Dingyuan of Beijing University of Science and Technology established a nonlinear mathematical model of impact mechanisms and wrote simulation programmes in BASIC, obtaining simulation data relatively consistent with measured results. During hydraulic rock breaker operation, due to high pressure, short impact cycle, and frequent oil flow switching, there is a constantly changing variable pressure chamber, so when hydraulic oil flows through various clearances it generates a large amount of heat, causing local high temperatures and affecting the impact device's performance and local lubrication; however research in this area is still a blank.

Due to the complexity of hydraulic rock breaker motion, nonlinear models are also built on the basis of certain assumptions, so there is not actually much difference between linear and nonlinear models in terms of describing the essential nature of things — only the mathematical model solution methods differ. Linear models use analytical solutions, while nonlinear models must use numerical methods through computers for solutions. Both can only approximate the motion patterns of the impact device, and to obtain more accurate description methods, computational fluid dynamics development is still needed.

It must be pointed out that with the development of hydraulic rock breaker technology, especially with the emergence of hydraulic-pneumatic combined and nitrogen-explosive hydraulic rock breakers, the working medium of the hydraulic rock breaker is not only oil but also gas; and the introduction of nitrogen has further increased the difficulty and complexity of theoretical research.

1.5.3 Research on Key Components of Hydraulic Rock Breakers

(1) Piston research

The design and manufacturing quality of the impact piston determines to a large degree the performance of the impact device. Chinese scholars have conducted significant research on this. Teacher Meng Suimin of Gezhouba Hydroelectric Engineering College, building on the linear model, used dimensionless analysis to conduct preliminary exploration of the influence of piston rebound velocity on hydraulic rock breaker operating parameters. Professor Liu Deshun of Xiangtan Engineering College, in the paper 'Calculation of rock drill piston rebound velocity', applied wave dynamics theory, and on the basis of analysing the working principle of rock drilling, proposed piston rebound judgement and rebound velocity calculation formulas for rock drills, obtaining the following conclusions: ① The piston rebound state and rebound velocity are related to the properties of the piston, chisel, and rock, and their influences are not independent but interrelated. ② The smaller the unloading stiffness coefficient of the rock, the larger the rebound velocity. The smaller the coefficient γ characterising the loading properties of the rock drill and rock, the larger the rebound velocity. ④ To achieve relatively ideal rock drilling efficiency, when designing an impact device, the characteristic coefficient γ should be controlled within the range 1 ≤ γ ≤ 2.

The industry has gradually formed some piston design guidelines:

1) The piston should be elongated and reduce unnecessary cross-sectional changes, to benefit energy transmission efficiency and chisel service life.

2) The area of the piston impact face should be as equal as or close to the area of the chisel tail end face, and a certain taper length should exist, to benefit the transmission of impact waves.

3) Full stroke and over-stroke of the piston must not damage the sealing structures at both ends.

4) Blank-firing hydraulic pad dimensions and sealing lengths of each piston segment must be designed well.

5) Correct material selection is required — the piston material must have high mechanical performance, high surface hardness, good core toughness, and very good abrasion resistance and impact resistance.

6) The mating clearance between piston and cylinder body should be reasonably determined, comprehensively considering leakage losses and machining accuracy. Generally the mating clearance between piston and cylinder body is 0.04 to 0.06 mm, and the mating clearance between piston and support sleeve is 0.03 to 0.05 mm.

(2) Distribution valve research

At present, the vast majority of hydraulic rock breakers use positional feedback valve-controlled piston systems, and realise high-speed reciprocating piston motion by changing the oil supply pattern in a certain chamber of the impact device. Although this control form is relatively simple, its transition process is relatively complex. During the valve switching process, time, velocity, stroke, oil consumption, and other parameters all change in stages, which can have a large effect on impact device performance. For this, Liu Wanling et al. of Beijing University of Science and Technology, through theory and experiment, conducted special research on the characteristics of control valves in hydraulic impact systems, obtaining the actual motion trajectory of the impact device valve being studied, revealing the patterns of directional valve motion, and determining the main parameters of the control valve affecting the performance of the impact device. Qi Renjun et al. of Central South University conducted theoretical analysis of the valve control process, optimisation research on valve structure and parameters, and obtained some beneficial regularity conclusions; aimed at possible velocity saturation and cavitation phenomena during high-speed motion of the directional valve, proposed effective solutions of reducing valve spool mass and stroke while appropriately increasing oil passage diameter. Liu Wanling and Gao Lanqing of Beijing Iron and Steel College, in 'Dynamic Characteristic Analysis of Hydraulic Rock Breaker Directional Valve — Simulation and Experimental Research', using BASIC programming, explored improving the dynamic characteristics of the valve, concluding that as the zero-overlap opening increases, the rear chamber pressure drops quickly, impact work increases, impact frequency decreases somewhat, and impact device efficiency improves; when the zero-overlap opening is too large, due to the decrease in sealing length at the valve shoulder, the valve's operation becomes unreliable.

(3) Accumulator research

The accumulator is an important component of the hydraulic rock breaker, and its structure directly affects the overall machine performance of the hydraulic rock breaker. Therefore, while researching hydraulic rock breaker performance, research on accumulators has also been carried out. In 1990, Japanese scholars Takauchi Yoshio, Tanimata Shu et al. conducted experimental and theoretical research, and based on the analytical model established, used the state equation to obtain the calculation formula for the accumulator nitrogen charge volume, and experimentally verified the correctness of the formula, providing a theoretical basis for designing the optimal accumulator. In 1986, Duan Xiaohong of Beijing University of Science and Technology, using the lumped parameter method, established a dynamic model of high-pressure membrane accumulators, and used both experimental and computational methods to analyse the frequency characteristics of the accumulator system, discussed the optimal coupling between the accumulator and hydraulic rock breaker, and pointed out that the optimal working zone of the impact device where the secondary harmonic response of the accumulator to system pressure changes is dominant in energy. In 1986, Teacher He Qinghua of Central South University published a paper 'Return Oil and Return Oil Accumulator of Hydraulic Impact Mechanisms', pointing out that the operating hydraulic pressure of the hydraulic rock breaker mainly depends on the inertia force of its own moving parts; this is a significant characteristic of the hydraulic rock breaker that distinguishes it from ordinary hydraulic machinery where the working hydraulic pressure depends mainly on external load. The return back-pressure is mainly the inertial hydraulic pressure formed by the oil accelerating as pistons or valves discharge oil to the return oil pipe; and it is pointed out that, because the discharge flow of the impact device differs from the flow variation pattern of oil flow in the return pipe, when the flow entering the return pipe is less than the oil flow moving in the return pipe, cavitation will occur. To reduce inertial return pressure and eliminate return cavitation, installing a return accumulator in the hydraulic rock breaker is proposed, and from this a return accumulator parameter design method is proposed. In recent years, Beijing University of Science and Technology has conducted research on the dynamic coupling characteristics of hydraulic rock breaker accumulators, compiled the simulation software package HRDP, and achieved results in verification calculations for optimal accumulator dynamic coupling characteristics.

(4) Research on blank-firing prevention devices and chisel rebound energy absorbers

Because unavoidable chisel rebound and blank-firing phenomena occur during hydraulic rock breaker operation, the working performance of the chisel rebound energy absorber and blank-firing prevention device has a great effect on the service life of the hydraulic rock breaker. Teacher Meng Suimin, in the paper 'Analysis of Rock Drill Piston Rebound Velocity', systematically analysed the factors of chisel tail rebound and explored methods of chisel rebound energy absorption. Liao Yide of Central South University, in the paper 'Theory and Experimental Research on Hydraulic Rock Drill Blank-Firing Buffer Devices', established a mathematical model of the blank-firing buffer process and conducted simulation research. Dr. Liao Jianyong, in the paper 'Design Theory and Computer-Aided Design of Multi-Stage Hydraulic Rock Drills', conducted computer simulation and optimisation design of chisel rebound energy absorber devices and blank-firing prevention devices. Liu Deshun of Central South University, in his doctoral dissertation 'Wave Dynamics Research of Impact Mechanisms', applied wave dynamics theory, derived rebound velocity calculation formulas for each part of the impact device, and pointed out that the rebound energy can be utilised through rational design of each part of the impact device. The Hydraulic Engineering Machinery Research Institute of Central South University developed a two-stage blank-firing buffer device, which fully utilised the capability of the chisel rebound energy absorber — a creative research achievement.

1.5.4 Research on Frequency-Tuning, Energy-Tuning, and Control Technology for Hydraulic Rock Breakers

With the development of hydraulic rock breaker technology, field construction has put forward new requirements for hydraulic rock breakers. To effectively improve production efficiency, it is required that the impact energy and impact frequency of the hydraulic rock breaker can change based on changes in rock properties. That is, under the premise of maximally utilising the installed capacity of the carrier machine, when rock is harder, the hydraulic rock breaker outputs larger impact energy and lower impact frequency; conversely it outputs smaller impact energy and higher impact frequency, thereby achieving higher production efficiency. To achieve the above objectives, extensive research has been carried out both domestically and internationally.

From theoretical research on hydraulic rock breakers, its output (impact energy and frequency) can mainly be adjusted by three methods: ① adjusting flow; ② adjusting stroke; ③ adjusting feedback pressure. Currently, the vast majority of domestic and foreign hydraulic rock breakers have only one fixed stroke — that is, their output is not adjustable. Of course, if such hydraulic rock breakers use the means of adjusting flow to adjust output, although theoretically feasible, it is practically not workable. Because changes in flow will cause synchronous changes in its output parameters, independent adjustment cannot be achieved.

Although some domestic and foreign manufacturers have designed and produced stroke-adjustable hydraulic rock breakers, because they are rigid-structure stepped adjustments and very inconvenient to use, with poor results, they are not welcomed by users. For stroke feedback distribution, its output working parameters are adjusted mainly by changing the system input flow, or adding multiple return stroke feedback signal holes, and through controlling the on-off of each signal hole to adjust the piston stroke, thus changing the hydraulic rock breaker's impact energy and impact frequency. For example, the Atlas-Copco three-speed hydraulic rock drill produced in Sweden. Central South University's YYG series automatic gear-shifting hydraulic rock breakers — limited by the structure, this principle can only achieve stepped adjustment of hydraulic rock breaker working parameters, and since impact system pressure and flow are proportional to the square of each other, simultaneous increase of impact energy and impact frequency will cause very large changes in the carrier machine power, limiting expansion of the hydraulic rock breaker's working range and working efficiency. Professor Takashi Takahashi of Akita University in Japan, in a paper, described adjusting the position of the return stroke signal port to achieve the purpose of changing the hydraulic rock breaker piston stroke. Experiments proved that when the piston stroke is increased by 10%, although the impact frequency decreases by 8%, impact energy can increase by 12%, which improved working efficiency and provided theoretical and experimental evidence for designing stroke-adjustable hydraulic rock breakers. Teacher He Qinghua of Central South University, in 'Research on Stroke-Adjustable Hydraulic Impact Machines', compared several types of gear-shifting methods and theoretically analysed the relationships between various working parameters of stroke-adjustable hydraulic impact devices and gear-shifting strokes; the results have obvious guiding significance for the design and use of gear-shifting hydraulic rock breakers. This book proposes the concept of independently and steplessly adjusting working parameters based on the pressure feedback principle, and has launched this new hydraulic rock breaker product. It mainly adjusts the single impact energy of the impact device by controlling the magnitude of the piston return pressure; simultaneously by controlling the variable pump flow, steplessly adjusts the frequency of the impact device, so that impact energy and impact frequency can each be independently steplessly adjusted within a relatively large range, while the carrier machine power change is small. Regarding the theoretical research, structural design, and control methods for this new type of hydraulic impact machine, the authors have conducted research on hydraulic impact devices with independent stepless adjustment of impact energy and impact frequency. Dr. Zhao Hongqiang, in the doctoral dissertation 'Research on New-Type Hydraulic Stone Crusher with Independent Stepless Adjustment Control', broke through the traditional stroke feedback control method of hydraulic rock breakers, adopted pressure feedback and variable pump flow control methods, and thereby realised independent stepless adjustment control of hydraulic rock breaker impact energy and impact frequency. Ding Wensi, in his doctoral dissertation, using the nitrogen pressure at the tail of the crusher as the control variable, did extensive work on forced distribution-type crushers controlled by high-speed switching valves, realising independent frequency tuning and energy tuning of crushers. Zhang Xin, in 'Research on a New-Type Pressure Feedback Hydraulic Impact Device System with Machine-Electric Integration', adopted single-chip microcomputer controlled high-speed switching valves to realise microcomputer control of the impact device. Yang Guoping, in the doctoral dissertation 'Research on a Pure Hydraulic Independent Stepless Frequency-Tuning Energy-Tuning Hydraulic Impact Device', proposed an intelligent impact device with a pure hydraulic control scheme that can realise stepless adjustment of hydraulic rock breaker impact energy and impact frequency through a pilot-type distribution valve handle.

1.5.5 Current State of Hydraulic Rock Breaker Simulation Technology Research

From a product design and development perspective, dynamic characteristic research on mechanisms is best done during the product development and design stage. Dynamic response simulation of hydraulic control systems has always been a field continuously studied by the hydraulic industry and is also a commonly used means for studying dynamic response characteristics of control systems.

The special working method of the hydraulic rock breaker determines that dynamic simulation analysis and testing must serve as the basic premise for mechanism theoretical design and development. After computers appeared, the obstacle of relying only on product testing to obtain accurate or reliable results of mechanism motion performance was broken. Researchers began using various methods to establish mathematical models describing hydraulic vibration and impact machine motion, analysing the parameter change processes of hydraulic rock breakers through simulation technology, and using virtual prototype technology to simulate the motion processes of impact machines. After design results are determined, the motion of the mechanism can be clearly understood and relevant performance parameters calculated, providing a good path for shortening new product development cycles, optimising design, and conducting dynamic performance analysis.

In the 1960s and 70s, foreign scholars began applying digital computers to impact machine simulation work. These works took front-rear chamber pressure as the variable, calculated the fluid inflow and outflow from each port, corrected with flow coefficients; then applied the gas state equation and energy balance equation, established micro-differential equations describing accumulator and piston state changes; after making certain approximate treatments of valve motion, adopted finite difference methods for numerical solution. Simulation results, especially performance parameters, were very close to measured values, obtaining satisfactory results. In Japan, researchers placed more emphasis on establishing computer models for specific hydraulic rock breakers for research, and introducing parameters obtained from experiments into simulation to carry out optimisation of structural parameters, impact parameters, and performance of hydraulic rock breakers, obtaining the optimal return oil port area, optimal accumulator charge volume and rear-chamber pressure-bearing area of the corresponding hydraulic rock breaker. While conducting simulation, Japanese researchers paid more attention to comparing simulation results with experimental testing results, and corrected the computer models according to test data. Sandvik company, after considering the effect of the impact piston shape on the energy transmission method, also designed and developed a computer simulation programme in this area. Using this programme: ① the energy transmission process of each part of the impact can be simulated; ② different designs of each system component can be simulated; ③ under different types of impact object conditions, the effects of various designs on energy transmission can be simulated. Sandvik's computer programme not only guarantees the manufacture of the optimal products but can also measure and understand the ability of all parameters to affect the impact system and the effect of changes in certain parameters on efficiency, and provides it to users as a practical and effective computing tool.

After the 1980s, domestic research on simulation technology and applications also began. Chinese scholars Tian Shujun, Chen Yufan, and others all established mathematical models using their respective methods. Tian Shujun et al. applied power bond graph — an advanced dynamic modelling technology — combining state-space analysis methods, mainly conducted research on dynamic simulation software for slide valve controlled hydraulic rock breakers. This research explored dynamic simulation modelling and programming of hydraulic rock breakers, providing a method and approach for many later simulation programmers, such as Professor Zhou Zhihong of Beijing University of Science and Technology who guided students Yan Yong et al. in using power bond graphs to establish dynamic equations for several types of hydraulic rock breaker pistons, directional valves, and each hydraulic flow equation and gas state equations; then compiled simulation programmes in computer language to carry out analysis of the main state change processes such as front-rear chamber pressure, flow, piston displacement and velocity of the hydraulic rock breaker, providing a platform for further research on the effect of hydraulic rock breaker parameter changes on its performance. With the rapid development of computers and software technology, Matlab and AMEsim software have been applied to hydraulic rock breaker system modelling and simulation, providing theoretical support for shortening research and development cycles and improving the design quality of new models.

1.5.6 Experimental Research Methods

Experiment is the basic means by which people recognise nature and transform the objective world — summarising and abstracting phenomena observed and data measured through experiment, finding internal connections and patterns, and forming theory. Experiment is the source of theory; experiment is the only judge for verifying theory.

Hydraulic rock breaker impact performance parameters are an important indicator for measuring its design, manufacturing level, and quality. The main parameters can all be measured through experimental means, and results expressed in the form of data, curves, or charts. Performance verification is mainly about measuring impact energy, impact frequency, system pressure, and flow. The measurement methods for these parameters currently have no unified international experimental standards. The currently commonly used hydraulic rock breaker impact performance testing methods are: stress wave method, photoelectric displacement differential method, electromagnetic induction method, contact method, high-speed photography, indicator diagram method, and energy method, etc.

The stress wave method is a method for measuring impact energy by measuring the stress wave generated on the chisel when the impact piston strikes the chisel. The photoelectric method uses the photoelectric conversion principle; through a photoelectric sensor, taking the impact piston position as the direct test measurement to obtain piston motion displacement, and then further calculate each performance parameter of the impact device. The photoelectric method, as a non-contact testing method, is very suitable for impact machines like hydraulic rock breakers that have long piston strokes, large diameters, and high velocity. The electromagnetic induction method uses the electromagnetic induction sensor system composed of a magnetic rod installed on the impact piston and a helical coil installed on the housing, uses the induced electromotive force generated by the coil cutting magnetic field lines as the magnetic rod reciprocates with the piston, and obtains the piston motion velocity based on the calibration relationship between electromotive force and impact velocity, and from this calculates piston impact energy.

The contact method is a method for calculating impact energy using the final velocity of the piston when it impacts the object being struck. In rock breaker performance testing, the above 4 methods are relatively common; other methods, either due to operational complexity and high cost, or due to incomplete reflection of piston motion state, are rarely seen in practical use.

It must be pointed out that the above stress wave method is only suitable for testing impact devices with relatively small impact energy such as hydraulic rock drills and pneumatic tools, and has greater difficulty in testing large impact energy of hydraulic rock breakers. The testing capacity of dedicated research units studying stress waves is generally not large and cannot handle testing of large hydraulic rock breakers; the noise and vibration generated by indoor testing is also not acceptable. As for the contact method, although simple to install, the results are not accurate enough and cannot be promoted. Only the electromagnetic induction method for hydraulic rock breaker testing is considered comprehensive in all respects: it can be used for both small impact energy hydraulic rock drills and large high-impact energy hydraulic rock breakers; it directly measures the piston motion velocity curve, thereby obtaining piston displacement and acceleration, which is very useful for people studying piston motion patterns. The only shortcoming is that the magnetic rod is easily damaged under high-frequency piston vibration.

Dr. Ding Wensi of Central South University, in the doctoral dissertation 'Research on a New-Type Pressure Feedback Nitrogen-Explosive Machine-Electric Integrated Hydraulic Stone Crusher System', proposed a new method for testing impact device output parameters — the gas pressure method. This method uses a pressure sensor to detect the effect on the pressure of the sealed nitrogen chamber installed at the tail of the piston during piston motion, and through a computer determines the piston stroke and motion velocity, thereby obtaining the two important output parameters of the impact device — impact energy and impact frequency. Compared with traditional testing methods, the non-contact gas pressure method has the advantages of strong vibration resistance, minimal preparation work, simultaneous measurement of impact energy and frequency, convenient calibration, small impact parameter error, and high accuracy. It can not only be used as a measurement and identification method for laboratory products, but can also be conveniently used for online testing in actual work. It has been applied in Jingye company's hydraulic test programme and written into the 'Hydraulic Rock Breaker' industry standard.

1.5.7 Research on Vibration, Noise, and Control

In addition to impact energy, impact frequency, and mass, the indicators for measuring hydraulic impact machine performance also include noise, machine body vibration, and energy utilisation rate, which are important aspects for evaluating overall performance. As environmental awareness grows, developed countries have increasingly strict restrictions on equipment noise. To adapt to market needs, the noise and vibration of hydraulic impact machines, as well as dust suppression, are gradually becoming important indicators of business competition; their control technology is now an important research topic. Scholars from various countries conduct research from structural and material aspects; structurally, measures such as built-in liner sleeves, silencing devices, or sandwiching vibration-damping steel plates are adopted to control vibration and noise. Krupp company has equipped all its medium and smaller products with sound-absorbing materials. Rammer company installs high-pressure water pumps and atomising nozzles on newly developed products to achieve dust reduction effects. In addition, using sensor technology to achieve precise positioning of hydraulic rock breakers, automatically drilling holes, stopping chisels and retracting chisels, and automatically adjusting impact energy and impact frequency based on working objects, etc.