Overview of Hydraulic Rock Breakers

1.1 Overview of Hydraulic Rock Breakers

A hydraulic rock breaker, also called a hydraulic crusher or hydraulic impact device, is a hydraulic impact-vibration machine. Using high-pressure hydraulic oil as the working medium, it achieves rapid back-and-forth piston motion inside a cylinder body through feedback between a valve control system and a cylinder-piston system, thus converting hydraulic energy into piston mechanical energy and driving the chisel to do work on the outside.

The main functions of a hydraulic rock breaker are: impact and vibration. Because of the high-power impact-vibration characteristics of a hydraulic rock breaker, it is widely applied in metallurgy, mining, railway, road, construction, municipal engineering, and property development. It can carry out excavation, breaking, demolition, and other operations on rock, concrete, steel ladles, slag, frozen ground, ice, concrete road surfaces, bridge decks, and buildings. In addition, by replacing the chisel, it can also be used for riveting, rust removal, tamping, and pile-driving operations.

Common application areas of hydraulic rock breakers are:

(1) Mining — quarrying, stone extraction, tunnel driving, grizzly bar breaking, secondary rock breaking;

(2) Metallurgical industry — furnace-dismantling machines, ladle-stripping machines, disassembly machines, tap-hole opening machines for cleaning steel ladle slag and furnace lining demolition;

(3) Municipal engineering — road surface breaking in water, gas, and electrical construction, hard foundation breaking, trenching, hole-drilling;

(4) Building construction — demolition of old buildings, concrete breaking, ground compaction;

(5) Roads and railways — road-opening blasting, concrete road surface breaking, highway repair, guardrail pile-driving, road-bridge demolition.

As a new high-efficiency hydraulic tool, compared with traditional pneumatic impact tools, hydraulic rock breakers have a series of unmatched advantages, mainly reflected in the following points:

—— Large impact energy. A hydraulic rock breaker can be matched and designed according to the oil pressure and flow provided by the carrier machine as well as the push force. Impact energy is generally 300 to 10,000 joules; the world's largest hydraulic rock breaker currently can deliver a single impact energy of 30,000 joules.

—— High working efficiency. Hydraulic rock breaker working efficiency generally reaches 60% to 65%; those with superior performance can reach 70%, while pneumatic tool working efficiency is only 20% to 30%.

—— Energy saving. The working medium of a hydraulic rock breaker is recyclable high-pressure hydraulic oil, simultaneously equipped with an accumulator; while the working medium of a pneumatic tool is compressed air, which not only consumes a large amount of thermal energy in the compression process, but also dissipates a large amount of energy in the exhaust process.

—— Low noise. Standard hydraulic rock breaker noise is 95 to 98 dB; low-noise types are 85 to 87 dB. Pneumatic tools, due to the explosive expansion sound when compressed gas is discharged, have noise uniformly exceeding 100 dB. In today's society where environmental protection requirements are increasingly strict, hydraulic rock breakers have important value.

—— Good constructability and low maintenance costs. A hydraulic rock breaker works alongside the carrier machine and can very easily realise operations at various spatial angles; the rock breaker is fully enclosed, component service life is long, maintenance is simple and convenient, and comprehensive operating costs are low.

1.2 A Brief History of Hydraulic Rock Breaker Development

In the early 20th century, people systematically studied pneumatic and hydraulic transmission, actively exploring hydraulic devices capable of transmitting high-power and control. In 1963, the German Krupp company applied for the world's first hydraulic vibration device patent; in 1967 it exhibited at the Hanover Exhibition the world's first carrier-mounted hydraulic rock breaker of practical value, the HM400. It was first used in foundation construction work, such as crushing concrete road surfaces, repairing foundations, digging trenches in hard ground, quarrying large blocks of rock … The French Montabert company also applied for a patent for the first handheld hydraulic rock breaker (BBH series) in 1964 and designed the BRH series hydraulic rock breaker product in 1969. Due to the powerful function and broad application prospects of hydraulic rock breakers, they were quickly taken very seriously in Europe, Japan, and other countries and developed rapidly. Many companies made large investments in the development, design, and testing of hydraulic vibration equipment, and hydraulic rock breakers of various sizes, types, and functions emerged one after another. Application areas continued to expand, technical performance continued to improve, and products continuously updated and replaced. Krupp launched hydraulic rock breaker vibration damping technology in 1985, improved the vibration damping system in 1995, released the 'Marathon' wear protection technology in 1998, and launched the 'ECO' and 'Marathon' series products in 2000. Montabert company launched the BRV series with self-adjusting energy in 1987, and in response to growing market demand launched the small BRP series rock breakers in 1992. Rammer company, founded in 1978 in Finland, although with a short history, became a dominant force in the hydraulic rock breaker field — from its very beginning it launched the S600 rock breaker, then the world's largest; the S2000 launched in 1981 weighed 3 tonnes; the 1986 series products used the 'Constant Blow Energy (CBE)' principle; the City series ultra-quiet products were launched in 1991; the 'City Pro' system developed in 1995 allowed operators to select hydraulic rock breaker performance based on the material being struck, as well as a water jet dust suppression system. Konan of Japan introduced Krupp technology in 1973 to produce MKB hydraulic rock breakers; then Japanese companies Furukawa, Teisaku, and Toku began developing hydraulic rock breakers on the basis of pneumatic impact devices; NPK was established in 1985. Soosan company, established in 1984, drove rapid development of Korean hydraulic rock breakers. Italian INDECO company was established in 1976; in 1986 it released the development of an 'intelligent hydraulic rock breaker' that can adjust impact frequency and energy based on rock hardness …

There are currently over 30 major hydraulic rock breaker manufacturers worldwide. Classified by origin they can be divided into European, Japanese, Korean, and domestic Chinese brands, of which only a few brands are sold worldwide. European hydraulic rock breaker manufacturers have the characteristic of combining manufacturing, brand, and service in one; production manufacturers both have strong technical R&D capabilities and also have their own marketing networks and customer service capabilities. Each hydraulic rock breaker manufacturer emphasises its own brand building, the industry concentration is high, and in recent years three major industry mergers and reorganisations have been completed, forming the three major brands of Rammer (including Toyo), Atlas-copco (including Krupp), and Doosan's Montabert. Japanese hydraulic rock breaker manufacturers are similar to European production manufacturers — they generally also have their own marketing networks and provide services to customers at the same time. Each hydraulic rock breaker manufacturer emphasises its own brand building, the industry concentration is relatively high. Only Furukawa, NPK, Toku, Teisaku, MKB, Toyo (already acquired by Rammer), and Okada seven companies are nationwide. Korean hydraulic rock breaker manufacturers have the characteristics of separating manufacturing, brand, and service; the overall industrial division of labour is relatively refined, with many small-scale parts manufacturing plants; there are close to a hundred hydraulic rock breaker distributors, but manufacturers with scale are only Soosan, Hanwoo, Daemo, MSB, and a few others. Table 1-1 gives an overview of annual output of major global hydraulic rock breaker manufacturers in 2010.

Table 1-1 Annual output overview of major global hydraulic rock breaker manufacturers in 2010 (excluding China)

China's research into hydraulic crushers started not late. As early as the mid-1970s, domestic scientific research institutes and universities had already entered this field, such as the Beijing Steel and Iron College, Zhongnan Mining College, Changsha Mining Research Institute, and Changsha Mining Research Institute. Chinese researchers conducted in-depth research on hydraulic vibration technology and obtained many research results, but due to the overall slow development of domestic hydraulic technology at that time and relatively low manufacturing levels, no substantial breakthrough was achieved in product development. After the 1980s, Chinese researchers, while conducting independent research, also introduced technology and took the lead in developing hydraulic rock drills and hydraulic stone crushers with their own characteristics in the mining field. Some domestic pneumatic tool plants and construction machinery plants also joined the research lineup, such as Jilin Tonghua Pneumatic Tool Plant, Shanghai Construction Machinery Plant, Shenyang Pneumatic Tool Plant, etc., all organised forces to carry out product research and testing; but due to backward production technology and unstable product quality, hydraulic rock breaker development was limited. In 1988, the German Krupp company came to China with products to hold a 'Hydraulic Rock Breaker Product Show', and more than 200 people from domestic scientific research institutes and enterprises attended the show; the powerful function of the products aroused great interest among participants, and Krupp products began to land in China. Seizing this opportunity, the Tianjin Engineering Machinery Research Institute and Harbin University of Technology analysed and researched Krupp products; Changzhi Hydraulic Parts Factory and Shanghai Construction Machinery Plant began trial production of their own products.

By the mid-1990s, with China's rapid economic development, rapid urban transformation, and increasing infrastructure investment, the degree of mechanisation in engineering construction continued to improve. The Chinese hydraulic rock breaker market ushered in the best development period in history; a number of well-known foreign enterprises began entering the Chinese market one after another. Domestic enterprises also rose to meet the competition, and after more than a decade of effort, gradually formed a number of well-known domestic brands such as Anhui Jingye (Jingye), Yantai Aide, Jiangsu Libosite, and Changzhi Hydraulic.