Present Situation and Development Trend of Hydraulic Technology Abroad
In foreign countries, the hydraulic industry is developing faster than the mechanical industry. The value of hydraulic products in the world is about 20 billion dollars. In the comparison of the United States, Japan, Germany and other major countries, the per capita output value of Japan is the highest. The main reason is that Japanese factories have a high degree of automation and perfect production management. In addition, Japanese enterprises have a large amount of foreign cooperation, spreading some parts to cooperative factories for processing, realizing parts specialization. According to statistics, the various countries hydraulic industrial production value accounts for 2 ~ 3 % of mechanical industry production value, but our country accounts for only 018 % or so, fully explains that utilization rate of our country hydraulic technology is low, need to expand its application fields.
（1）Overview of the world hydraulic industry market
The application field of hydraulic technology is more and more extensive, according to analysis, construction machinery, agricultural machinery and other walking machinery is the main user of hydraulic industry; In industrial machinery, machine tools, metallurgy, plastic machines are the main users. Due to machine tools, plastic machines, robots and other industries part of the transmission has been replaced by electrical transmission, its demand is reduced, construction, engineering, metallurgy and other requirements of the proportion of significantly increased. According to foreign information, construction machinery and industrial vehicles hydraulic utilization rate has an increasing trend, machine tools and other industrial machinery hydraulic utilization rate has a declining trend, the main reason is due to the continuous improvement of the electrical integration level of the main engine, the electrical system price greatly increased and so on.
（2）Hydraulic product composition ratio analysis
In recent years, due to the needs of the development of mainframe products, the composition of product varieties has changed:
A. The ratio of piston pump composition has an increasing trend. Gear pump little change, and blade pump is down 017 %. B. Plunger motor component ratio has an increasing trend. C. The proportion of valves, general three types of valves in the total production will decrease, and the proportion of stack valves, cartridge valves, proportional valves, multiway valves, etc., will increase significantly. Electromagnetic reversing valve output and sales account for the largest proportion. D. As a result of the emphasis on hydraulic system pollution control, filter sales have increased significantly.
（3）Change and present situation of production mode of hydraulic industry abroad
In order to meet the needs of users, the host variety is increasing day by day, the product update speed is accelerated, the corresponding requirements of hydraulic components to increase varieties, to achieve diversification, so the hydraulic parts belong to the mass production of products are relatively reduced, most belong to batch or small batch production. In order to adapt to this trend, the foreign production mode has also changed. The changes of the production mode and its current situation are described as follows: Several production modes (cold processing of main parts)
① Production line based on ordinary machine tools. This way belongs to the level of the 1950s and 1960s, generally arranged according to the flow mode of the aircraft group, mainly rely on tooling and special aircraft to ensure accuracy, this way is poor flexibility, low efficiency, has been basically eliminated in foreign countries;
② Production lines based on high-efficiency semi-automatic machine tools and composite machine tools. The production line is generally arranged in U-shape, this production line has high production efficiency, but poor flexibility, suitable for mass or batch production;
(3) To numerical control (NC), machining center (CNC) and manufacturing unit (FMC) mainly composed of the production line, high precision, high efficiency and flexibility integrated into one, using this way than the first mode to improve the efficiency of 5 ~ 6 times, widely used in foreign countries;
(4) Flexible production line (FMS), flexible automatic production line (FTL) based production mode. Japan, the United States, Germany's hydraulic enterprises widely used this equipment, it is suitable for multiple varieties, small and medium-sized batch production, can achieve sized batch production, can achieve unattended, high production efficiency, significantly shorten the production cycle. As for processing mass parts, such as electromagnetic valve body, flexible automatic production line (FTL) is used abroad. It is composed of CNC sliding table, transmission device, deburring and cleaning device, precision stranding machine, automatic parts detection and other equipment arranged in a straight line;
⑤ assembly machine tool production line. Automatic production line mainly composed of modular machine tools, generally rigid, some can be replaced with a small number of varieties, the replacement of products takes time of 1 ~ 2 days, this kind of production line flexibility is poor, but suitable for large batch, product design life long parts production, such as electromagnetic valve body, multi-way valve body, gear pump shell, general production capacity of 100,000 ~ 300,000 pieces. There are still such production lines in the United States, Germany and Taiwan. This mode of production will be replaced by flexible and automated production lines.
Pay attention to auxiliary process oems require high cleanliness of hydraulic parts and systems. All countries attach great importance to the cleaning and punctures process of hydraulic parts. After the casting enters the factory, electrochemical cleaning, shot peening and rust prevention treatment areadopted. The main methods include bubble high-pressure injection (pressure 5 ~ 10MPa), ultrasonic wave and gas bath pressure injection(pressure 5 ~ 10MPa), ultrasonic wave and gas bath (trichloroethane) and other cleaning methods. Foreign batch and mass production of parts using a variety of techniques, such as thermal energy, extrusion, vibration lighting, high pressure injection, electrolysis, liquid sandblasting, nylon brush, cutting and other techniques. Cleaning and removing thorns is an indispensable process in the production of hydraulic parts.
In recent decades, with the help of microelectronic technology, hydraulic technology has developed electro-hydraulic transmission and control vigorously, so that hydraulic technology has new vitality. The main competitor of hydraulic technology is mechanical transmission and electrical transmission, as long as along the direction of mechatronic integration, and constantly tracking and transplantation of information technology, computer technology, friction and wear technology, lubrication technology, automatic control technology and new materials and new processes and other results, give full play to the advantages of hydraulic technology, such as high power density, to overcome the shortcomings of oil leakage and noise, Hydraulic technology as an important part of modern transmission and control, will continue to expand the field of application, maintain strong competitiveness, and keep moving forward.