Excavators are at overseas market
The first manual excavator has a history of more than 130 years since it came out. During this period, it has experienced the gradual development process of fully automatic hydraulic excavator, which is driven by steam, semi-rotary excavator, electric power and internal combustion engine.
Excavators in developed countries are produced earlier. France, Germany, the United States, Russia and Japan are the main producers of single-bucket hydraulic excavators with bucket capacity of 3.5-40 m3. Since the 1980s, they have been producing super-large excavators. For example, the Peeling Excavator with bucket capacity of 50-150 m3 produced by Marion Company in the United States, the walking shovel excavator with bucket capacity of 132 m3, the Peeling shovel excavator with bucket capacity of 168.2 m3 produced by B-E Company, and the Peeling Excavator with bucket capacity of 107 m3 are the largest excavators in the world at present.
Since the late 20th century, the production of excavators in the world has been developing in the direction of large-scale, miniaturization, multi-function, specialization and automation.
1) Developing excavators with multi-varieties, multi-functions, high quality and high efficiency. In order to meet the needs of municipal construction and farmland construction, micro excavators with bucket capacity less than 0.25 m3 have been developed abroad, and the minimum bucket capacity is only 0.01 m3. In addition, the largest number of medium and small excavators tend to be multi-functional, equipped with a variety of working devices - in addition to the front shovel and back shovel, but also equipped with lifting, grab, flat slope bucket, loading bucket, rake, broken cone, twist drill, electromagnetic sucker, vibration rammer, bulldozer, impact shovel, set fork, overhead work frame, hinges. Pan and shovel, etc., to meet the needs of various construction. At the same time, special excavators for special purposes, such as low specific pressure, low noise, underwater excavators and amphibious excavators, will be developed.
2) Rapid development of fully hydraulic excavators, continuous improvement and innovation of control methods, so that excavators from simple lever control to hydraulic control, pneumatic control, hydraulic servo control and electrical control, radio remote control, computer integrated program control. Radio operation is used in dangerous areas or underwater operations, and computer control receiver and laser guidance are combined to realize the full automation of excavator operation. All of these, the full hydraulic excavator laid the foundation and created a good premise.
3) Emphasize the adoption of new technologies, new processes and new structures, and speed up the development of standardization, serialization and generalization. For example, the excavator manufactured by Atlas Company in Germany is equipped with a new type of engine speed regulating device to make the excavator work at the speed most suitable for its operation requirements; the new C series LS-5800 hydraulic excavator manufactured by Lincoln-Belt Company in the United States is equipped with a fully automatic control hydraulic system, which can automatically adjust the flow and avoid driving. Waste of power. CAPS (Computer Aided Power System) is also installed to improve the working power of excavators and give full play to the function of hydraulic system. Five new FJ series excavators produced by Sumitomo Corporation of Japan are equipped with computer aided power control system connected with hydraulic circuit, which uses precision control mode selection system to reduce fuel and power generation. The consumption of motive power and hydraulic power has prolonged the service life of the spare parts; the oil pump regulating system of excavator manufactured by O&K Company in Germany has the characteristics of confluence, which makes the oil pump have the greatest working efficiency; Shengang Company in Japan adopts intelligent control system on the new type of 904.905.907.909 hydraulic excavator. Even inexperienced drivers can perform complex operations; Liebherr Corporation of Germany has developed an ECO (Electronic Control Operation) control device, which can adjust the performance of excavators according to the operation requirements and achieve high efficiency and low fuel consumption; Caterpillar Corporation of the United States has adopted the latest technology on the new B-system excavator. The 3114T diesel engine, the torque load sensing pressure system and the power mode selector further improve the efficiency and stability of the excavator. EPOS-electronic power optimization system is adopted in DH280 excavator by Dooshan Construction Machinery Company of Korea. According to the change of engine load, the absorbed power of hydraulic pump is automatically adjusted so that the engine speed is always near the rated speed, i.e. the engine is always running at full power, which makes full use of the start-up. The power of the machine and the working efficiency of the excavator are improved, and the engine is prevented from flameout due to overload.
4) Updating design theory, improving reliability and prolonging service life. In the United States, Britain, Japan and other countries, the finite-life design theory has been popularized to replace the traditional INFINITE-LIFE design theory and method. Advanced technologies such as fatigue damage accumulation theory, fracture mechanics, finite element method, optimization design, electro-hydraulic servo fatigue test technology controlled by computer and fatigue strength analysis method have been applied. In the strength research of hydraulic excavator, it promotes the high quality, high efficiency and competitiveness of products. The dynamic design analysis method for evaluating dynamic strength was put forward in the United States, and the theory for predicting product failure and updating was established. Japan has formulated a strength evaluation procedure for hydraulic excavator components and developed a reliability information processing system. Under the guidance of the above basic theory, with the help of a large number of tests, the research cycle of new products is shortened, the process of upgrading hydraulic excavators is accelerated, and their reliability and durability are improved. For example, the operation rate of hydraulic excavator reaches 85%-95%, and its service life exceeds 10,000 hours.
5) Strengthen the protection of drivers and improve their working conditions. Hydraulic excavator adopts cab with falling object protection structure and overturning protection structure, installs adjustable elastic seat, and uses sound insulation measures to reduce noise interference.
6) Further improvement of hydraulic system. The hydraulic system of medium-sized and small-sized hydraulic excavators tends to change to variable system. Because the variable system compensates for the decrease of pressure by increasing the flow rate during the operation of the oil pump, so that the power of the hydraulic pump can be kept constant, that is, the hydraulic excavator equipped with the variable pump can make full use of the maximum power of the oil pump regularly. When the external resistance increases, the flow rate (speed) is reduced, and the excavation force is multiplied. The three-loop hydraulic system is adopted. There are three independent working movements that do not affect each other. The power matching with the rotary mechanism is realized. The third pump is connected to other working movements and becomes the second independent fast motion of the open loop. In addition, hydraulic technology is widely used in excavators, which creates conditions for the application and popularization of electronic technology and automatic control technology in excavators.
7) Rapidly expand the application of electronic and automation technology in excavators. In the 1970s, in order to save energy consumption and reduce environmental pollution, make excavators operate easily and safely, reduce excavator noise, improve driver working conditions, and gradually apply electronic and automatic control technology in excavation. With the improvement of performance requirements for excavators in terms of efficiency, energy saving, environmental protection, portable operation, safety, comfort, reliability and durability, the application of Electromechanical-hydraulic integration in excavators has been promoted, and its various performances have made a qualitative leap. In the 1980s, high and new technologies with microelectronics technology as the core, especially the application of computers, microprocessors, sensors and measuring instruments in excavators, promoted the application and promotion of electronic control technology in excavators, and has become an important symbol of the modernization of excavators, that is, advanced excavators are equipped with engines. Electrical control systems such as idle speed and throttle control system, power optimization system, working mode control system, monitoring system, etc.
8) More attention should be paid to environmental protection. CAT, Komatsu and other manufacturers have launched excavators to meet the three-time emission requirements.
