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With the rapid development of modern science and technology, the expansion of industrial production scale and the improvement of automation, cranes are more and more widely used and play a greater role in the process of modern production, and the requirements for cranes are higher and higher. In particular, the wide application of computer technology has promoted the emergence of many interdisciplinary design methods and promoted the improvement of modern manufacturing technology and testing technology. The fierce international market competition also depends more and more on technology competition. All these promote the technical performance of the crane into a new stage of development.

China is entering the global international competitive market at an unprecedented speed. China's crane manufacturing industry is facing a new situation of both opportunities and challenges. Therefore, the continuous development and innovation of crane is the key. According to the new theory, new technology and new trend of cranes at home and abroad, combined with examples, this paper briefly discusses the characteristics and development trend of modern cranes.

  1. Large scale, high speed, durability and specialization of key products

Due to the continuous expansion of industrial production scale, the increasing improvement of production efficiency and the gradual increase in the proportion of material handling costs in the production process, the demand for large or high-speed cranes is increasing. The lifting capacity is getting larger and larger, the working speed is getting higher and higher, and higher requirements are put forward for energy consumption and reliability. Crane has become an important part of automatic production process. The crane is not only easy to use, easy to maintain and operate, but also has good safety, less faults and long average trouble free working time. Reliability is the focus of product competition in the international market. Many large foreign companies have formulated reliability internal control standards. In order to catch up with and surpass the world level in the performance of cranes in China, the key is to improve the reliability and make the cranes have excellent durability, trouble free, maintainability and economy.

At present, the lifting capacity of the world's largest floating crane is 6500t, the lifting capacity of crawler crane is 3000t, the lifting capacity of bridge crane is 1200t, and the running speed of automatic three-dimensional warehouse stacking crane is 240m / min.

Due to the diversity of industrial production modes and user needs, the market of special cranes is expanding and the varieties are constantly updated, so as to meet special needs with unique functions and play a role. The functions, performance and adaptability of special cranes for metallurgy, explosion-proof, anti-corrosion and insulation cranes and special cranes for railways, ships and vehicles are increasing. German Demag company has developed a special crane for aircraft maintenance, which has opened a market in the international market. This crane has large span, large lifting height and high stopping accuracy. A retractable and rotary maintenance platform is installed under the lifting trolley, which can reach any part of the aircraft. With the rapid development of nuclear power plants in the world, special cranes for nuclear power plants have also been developed accordingly. For example, the ring bridge crane in the reactor room works in a radioactive environment, which is used to lift dangerous loads such as pressure vessel head cover and reactor internals. It is required to have high reliability, good safety, automatic positioning and slow lowering of goods, and has a variety of protective devices and special safety devices.

2 Series products are modularized, combined, standardized and practical

Many cranes are series and batch products. Adopting the system multi-objective overall optimization method to design the crane series has become the focus of development. By comprehensively considering the performance, cost, process, production management, manufacturing batch, use and maintenance and other factors, the main parameters of the series are reasonably matched, so as to improve the performance of the whole machine and reduce the manufacturing cost, Improve the degree of generalization, and form a series of products with multiple varieties and specifications with fewer parts and components to fully meet the needs of users.

Modular design is used to replace the traditional whole machine design method. The components, components and parts with basically the same function on the crane are made into standard modules with multiple uses, the same connection elements and interchangeability. Through the combination of different modules, cranes of different types and specifications are formed. To improve the crane, only a few modules are needed. To design a new type of crane, only different modules need to be combined again. Due to the improvement of the degree of generalization, the products produced in a single small batch can be changed into module production with considerable batch, so as to realize high-efficiency professional production and reduce manufacturing costs. It can be combined into multiple varieties and specifications of cranes in the form of fewer modules, so as to meet the market demand and increase the competitiveness.

The bridge crane produced by German abus and Demag company fully considers modularization and combination, so as to match the parameters of series, complete machine, mechanism, components and parts, and achieve the economic and reasonable matching effect of capacity distribution. The product of lifting weight and lifting speed is used as a constant to make the main components of the lifting mechanism universal. Then more specifications are derived from the change of pulley magnification. 5 ~ 125t bridge crane series, with various working levels, only four basic lifting trolleys are required. The standard wheel box module series developed by the company has multiple groups of connecting holes on it. Different types of driving units can be selected and assembled into trolleys. It can be combined with metal structures and used as the running machinery of various bridge cranes, gantry cranes, roadway Stacking Cranes or other rail type lifting and transportation machinery. Its wheels have a variety of tread forms to choose from. Because it is not limited by base distance, it has flexible combination and wide application. The company's end beam standard module series has been commercialized, and the main beam is connected with the friction ring and high-strength bolt, which improves the interchangeability and dimensional accuracy and reduces the processing volume of the joint surface. It can be connected with any main beam quickly and effectively. There are two types of end beam modules suitable for single beam or double beam. The applicable end beam model can be determined according to the lifting weight and span.

3 Miniaturization, lightness, simplification and diversification of general products

A considerable number of cranes are used in general workshops and warehouses. The requirements are not very high and the work is not very heavy. How to improve the applicability of these cranes and reduce the manufacturing cost is the key to win the market competition. Considering the comprehensive benefits, the crane is required to reduce the overall height, simplify the structure, reduce the self weight and wheel pressure, reduce the height of the whole building, lighten the building structure, and reduce the cost and use and maintenance cost. Therefore, electric hoist bridge crane and light beam crane have a faster development, and most of them will replace small and medium tonnage general-purpose bridge crane.

The demand of users promotes the diversity of cranes. The range of series parameters of the crane is further expanded, the function selection is further increased, and the multi-purpose product of one machine is further developed to enhance the strain capacity. In general use occasions, the proportion of wireless remote control operation will gradually increase.

After long-term development and innovation, German abus and Demag have formed a series of light combined standard cranes. The whole series is composed of several varieties of combined I-shaped single beam, suspended box single beam, angle trolley box single beam and box double beam. There are 15 types of connection between the main beam and the end beam, which can meet the requirements of different buildings and different lifting objects. There are three kinds of single speed and three kinds of double speed for each specification of crane. There are seven operation modes: the ground manual switch moves by itself, the manual switch moves with the trolley, the manual switch is fixed, the far-infrared or radio remote control, the cab is fixed, the cab moves with the trolley, and the cab moves by itself. In addition, different conductive forms and different electric control forms can be matched with hundreds of cranes through different combinations, Fully meet the different needs of users. Another advantage of this crane is lightness. Compared with domestic products, the lifting capacity is 32t, the span is 25.5m, the self weight of domestic double beam bridge crane is 46.4t, the self weight of electric hoist bridge crane is 28.3t, while the self weight of DEMAG electric hoist bridge crane is only 18.5t, which is 60% and 35% lighter than domestic products respectively.