How to Achieve an Efficiency of 1500t/h for a Gantry Crane?

In order to innovatively design a high-efficiency gantry crane, optimize its main technical parameters, so that the unloading efficiency can reach 1500t/h:
Adopting a suspended structure discharge system to shorten the cycle time, improve the working efficiency, reduce the height of the center of gravity of the whole machine, and improve the stability of the whole machine;
The innovative design of the four-drum hoisting mechanism ensures the compact coordination of the overall arrangement of the mechanism on the premise of satisfying the equipment load capacity and operation stability;
Design an automatic recycling system for spreading materials, collect the materials scattered by the grab bucket, and automatically recycle them into the unloading system, reduce the manpower and material resources for cleaning, and avoid the environmental pollution caused by spreading materials;
Develop a semi-automatic control system suitable for the bucket door machine, which automatically intervenes at the right time after grabbing the material to take over the unloading control process, which effectively improves the loading and unloading efficiency and reduces the driver’s operating intensity.

Introduction

At present, the machinery widely used in the terminal bulk cargo operation in the world includes general gantry cranes or gantry cranes, grab ship unloaders, and various continuous ship unloaders. The main models of domestic general gantry cranes are those with a tonnage of 40t and below Portal cranes and gantry cranes require a rotation angle, which affects the operation efficiency. As specialized equipment, grab or chain bucket ship unloaders generally have an efficiency of 800~4500 t/h, but they are self-important and require high construction costs and requirements for the wharf. Continuous ship unloaders have high requirements for cargo types and high construction costs. The crane with bucket door is an innovation based on the general door crane, and the efficiency is between the general door crane and the ship unloader, and generally does not exceed 1000 t/h.
On June 27, 2015, the Ministry of Transport and the National Development and Reform Commission jointly issued a notice that the first batch of 4 ports in China (Dalian Port, Tangshan Port Caofeidian Port Area, Qingdao Port, Ningbo Zhoushan Port) 5 wharfs with a total of 7 berths were approved A 400,000-ton super-large ore carrier is docked. On the evening of June 30 of the same year, the “Yuanzhuohai” ship under China Mining Shipping arrived off the coast of Qingdao, ushering in the era of large ships in Chinese ports.
In recent years, the loading, unloading and transit of heavy cargo has increased in the proportion of the total number of loading and unloading logistics, which has led to an increasing demand for large cranes. The efficiency of loading and unloading equipment for handling 400,000-ton super-large transport ships requires Grab ship unloaders with over 3,500 t/h and over 50m reach, each with a dead weight of more than 2,500 t and a cost of more than 60 million yuan, have higher requirements on the gauge, bearing and cost of the wharf. For general and multi-purpose ports, the investment is large and the utilization rate is relatively low. The high-efficiency bucket gate machine has low requirements on the wharf and low cost. It is suitable for different ship types and different types of goods. Under normal circumstances, two sets can meet the loading and unloading requirements of 400,000-ton super-large transport ships, and the cost is much lower than that of a single A dedicated grab ship unloader. Therefore, the research and development of large-scale intelligent and high-efficiency bucket gate cranes is the most economical and practical loading and unloading equipment to adapt to the large-scale sea-going ships in my country’s ports.
In recent years, the gantry crane has become more and more popular in the market as a multi-functional and more efficient equipment than the bulk cargo gantry crane. It is a gantry crane with its own unloading system, which can be used as a professional equipment to unload grain with a grab bucket. , coal, wood chips and other bulk goods, and can also be used as an ordinary door crane to load and unload wood, steel plates, equipment and other general goods. Because the rotating mechanism can not be activated when the grab bucket is used, the production efficiency is greatly improved. At present, according to the types of goods, there are mainly grain-operated dolmen machines, coal-operated dolmen machines, and wood-chip dolmen machines, among which coal and ore-operated dolmen machines are in greatest demand. , the user put forward the further improvement of loading and unloading efficiency and large tonnage, large-scale requirements. Therefore, in order to meet the requirements of different wharfs, different ship types and different productivity, it is necessary to develop different tonnages with bucket doors. The width of the 300,000-ton ship is 60m, and the loading and unloading equipment needs at least 50m in width. To achieve efficient loading and unloading, the production efficiency must be at least 1000t/h. Optional equipment includes 1500t/h bridge grab ship unloader, 70t-50m Universal portal crane, 1500t/h high-efficiency gantry crane, etc.
Comprehensive comparison: bridge-type grab ship unloaders are expensive; general-purpose portal cranes are fast and large, and have high requirements for equipment and drivers; portal cranes with buckets are between the two. By designing a reliable and efficient unloading system, The built-in funnel reduces rotation, reduces the work cycle time, and reduces the driver’s work intensity through semi-automatic control. Therefore, it is cost-effective to choose a crane with a bucket gate seat, which can meet the loading and unloading needs of a 300,000-ton ship.

1. Research status at home and abroad

Since 2004, in order to adapt to the changing types of goods, major domestic ports have begun to use bucket gate machines, but they are basically 16t coal, wood chips, grain, and ore bucket gate machines. With the trend of larger ships, 25t bucket gate machines are also used. gradually increase. Most of the machines with bucket gates are used to unload coal and ore. Large-scale operations such as grain storage require specialized machines with bucket gates for unloading soybeans, while papermaking enterprises such as Jinhai Paper, Oji Paper, Jindong Paper, and Senbo Pulp need to unload wood chips. With bucket door machine and coal belt bucket machine with its own power generation business needs. Soybeans have good fluidity, and the unloading system is easy to design; there are many types of coal, bituminous coal has poor wet fluidity, easy to block materials, and the ore powder has high viscosity and poor flow, so the unloading system needs a targeted design; It is a machine with a bucket door that is difficult to design.
At present, the largest machine with bucket door in China is 40t, which is used for loading and unloading coal and ore, and the production efficiency reaches 1000t/h.
my country is the main country in the world that designs and manufactures bucket gate machines. Foreign machines with bucket doors are rarely used. Japan’s Mitsubishi and Sumitomo have designed dual-purpose machines, but they are all continuous loading and unloading types without grab spreaders. In my country’s ports, the cargo types of bulk cargo terminals are generally changeable and must be adapted to the type of cargo. Therefore, the equipment is required to be multifunctional, and the bucket door machine has this function, while the continuous type restricts the type of cargo, which is more suitable for a single type of cargo. of specialized docks.
At present, there are not many 300,000-ton docks in the world, so there are few equipment for loading and unloading goods. At present, there is no 55t-50m large-scale equipment with bucket gate. With the official debut of the 400,000-ton ore carrier in China, the matching loading and unloading equipment will also be put into use. The grab ship unloader is efficient and reliable; the bucket gate machine is efficient, cost-effective and flexible, and can unload different bulk cargo, general cargo and containers.
At present, there are many machines with bucket gates with different types of goods, different tonnages and amplitudes. Domestic grain systems mostly use bucket gate machines with scraper machines, which have high efficiency and good environmental protection effects. Some ports use a cover belt type terminal conveying system, which makes the loading and unloading process completely closed and effectively prevents spillage and dust. The large-scale machine with bucket gate has the performances of reliability, safety, high efficiency and energy saving, which can meet the needs of major ports and provide effective support for the rapid development of ports and the national “Belt and Road” initiative.

2. Innovation points and key technologies

2.1 Breakthrough in product performance
The production efficiency of traditional products of the same type is below 900t/h, which cannot meet the loading and unloading needs of bulk cargo ports that dock with ships above 200,000 tons, which restricts the development of products with bucket portal cranes. The 55t-50m gantry crane with bucket has a lifting capacity of 55t, a hook lifting capacity of 80t, a maximum amplitude of 50m, and a rated production capacity of 1500t/h. It has the advantages of large lifting quality, large-scale, short operation time, and material is not easy to spread. The hopper and dock belt conveyor are not easy to wear, the selection of electromechanical accessories is simple, the dust is small, environmental protection, and high efficiency. By optimizing the main technical parameters, reducing the vertical height of the funnel to the wharf surface, and innovatively designing the gantry structure, the operation cycle time is reduced and the work efficiency is improved. A number of technical indicators have achieved substantial breakthroughs. The physical drawing and design drawing of DM5550 gantry crane are shown in Figure 1.
Equipment | How to achieve an efficiency of 1500t/h for a gantry crane? 2.1.1 Optimization of main technical parameters
In order to meet the loading and unloading requirements of 300,000-ton ships, the 55t-50m gantry crane has made breakthroughs in technical indicators. The 300,000-ton ship has a width of 58m and a depth of 30m. To load and unload such a large transport ship, on the one hand, the working range and lifting height must be satisfied, and on the other hand, in order to achieve good economic benefits, the work efficiency is affected. The two major factors of lifting weight and working speed should also be strongly guaranteed. Through the optimized design of the four-link, the reasonable size parameters of the boom, the trunk bridge and the large tie rod are determined to meet the design goals. Specific main parameters:
(1) The lifting capacity of the grab bucket is 55 t, and the lifting capacity of the hook is 80 t.
(2) The full-load lifting speed is 85 m/min, the no-load lifting speed is 130 m/min, and the luffing speed is 80 m/min.
(3) The minimum amplitude is 13 m, the maximum amplitude is 50 m, and the lifting height under the grab bucket is 30 m.
(4) The loading and unloading efficiency reaches 1 500 t/h.
2.1.2 Gantry structure design
The traditional gantry structure with bucket gantry used to support and arrange the unloading system has 2 beams, the upper beam is fixed with a movable telescopic beam, and the hopper is fixed on the telescopic beam. When working, the hopper moves to the cabin synchronously with the telescopic beam. Above, in order to prevent the unloading system from touching the highest point of the ship when the ship is empty, the bottom end of the hopper should be at least 2m higher than the highest point of the ship, so the lifting stroke is too long, resulting in long operation cycle time and low efficiency.
The 55t-50m gantry crane with bucket is designed with a concave single-layer gantry structure, the hopper is arranged in the groove of the gantry beam, and the unloading system is suspended under the gantry, which lowers the center of gravity of the crane with bucket door and improves the overall Machine stability, but also reduce the weight of the gantry, reduce energy consumption and save resources. The physical drawing and design drawing of the gantry structure are shown in Figure 2.
Equipment | How to achieve an efficiency of 1500t/h for a gantry crane? See Figure 3 for a comparison chart of the old and new type of unloading system. During operation, the funnel is generally improved from the upper part of the ship to the side of the ship, thereby reducing the lifting stroke of the grab bucket, reducing the time of a single working cycle and improving work efficiency. For a large grab with a lifting capacity of 55 t under the grab, the length and width of the funnel mouth should be large, and the width of the upper mouth of the funnel should be 9m. At the same time, in order to ensure the smooth outflow of materials, the inclination angle of the funnel wall should not be less than 60°. It is determined that the overall height of the funnel is not less than 6m, plus the safety distance between the lower mouth of the funnel and the deck of the ship, the lifting work stroke of more than 8m can be reduced, and the work cycle time can be reduced to 11.3s.
Equipment | How to achieve an efficiency of 1500t/h for a gantry crane? 2.1.3 Productivity calculation
The working cycle diagram of DM 5550 with bucket portal crane is shown in Figure 4. The work productivity comparison of DM 5550 and DM 4043 with bucket portal crane is shown in Table 1.
Equipment | How to achieve an efficiency of 1500t/h for a gantry crane? The 55 t 50 m gantry crane reduces the time of a single work cycle in a number of ways, with significant results. The single cycle time of the DM 5550 with bucket door machine is 78.4 s, the self-weight of the grab bucket is 20 t, and the production efficiency is 1 607 t/h, reaching the design target value.
Compared with the DM 4043 gantry crane, the production efficiency of the DM 5550 gantry crane is increased by 40%. Taking into account that the traditional product mechanism works at a lower speed than the DM 5550 gantry crane, the production efficiency will increase by more than 40%.
2.2 Four-motor synchronous hoisting mechanism
Innovatively designed hoisting mechanism with bucket portal crane with independent drive and synchronous control. The conventional four-rope grab gantry is driven by double drums and double motors. Due to the large lifting weight and fast lifting speed of this product, if the traditional design method is adopted, the power of a single motor will reach more than 500 kW. Such a mechanism is extremely bulky and cumbersome, which is not conducive to the overall layout.
The 55 t 50 m gantry crane with bucket gantry is innovatively designed with four motors to independently drive the hoisting mechanism. This design has higher requirements for control. A little carelessness will cause the grab bucket to spill material, affect the work efficiency, and also cause environmental damage. Pollution. Therefore, the speed closed-loop and position closed-loop double closed-loop control mode is adopted for the motor in control. Through the incremental encoder installed on the high-speed shaft of the motor, the speed closed-loop control of the inverter on the motor is realized, and the control accuracy is 0.01%. On this basis, the pulse number of the incremental encoder is collected by PLC. Under the condition of hook or grab, the pulse deviation of the encoders of the two supporting motors and the two switching motors is compared in real time, and the inverter is controlled by the PLC. Real-time speed adjustment for absolute synchronization of 2 support motors and 2 switch motors. The layout of the lifting mechanism is shown in Figure 5. The main parameters of the hoisting mechanism are shown in Table 2.
Equipment | How to achieve an efficiency of 1500t/h for a gantry crane? Equipment | How to achieve an efficiency of 1500t/h for a gantry crane?

3. Features of 1500t/h high-efficiency gantry crane

(1) Provide new options for port strategic planning.
The overall structure is optimized and designed to increase the operating capacity of the gantry crane to a new height, which can meet the operation needs of bulk cargo, and at the same time has the function of a general gantry crane, which has strong adaptability and high efficiency for general cargo operations. , good reliability, with the ability to resist economic fluctuations and market risks, providing a solid foundation for the stable development of the port logistics industry.
(2) High cost performance and low cost of use.
The 55 t 50 m bridge-type grab ship unloader with a gantry crane has an unloading efficiency of 1 500 t/h, the maximum operating range is 50 m, and the forward reach of the same operating capacity is more than 50 m. The weight is more than 2,000 t, and the construction cost is higher than 40 million yuan. It has high requirements on the gauge, bearing requirements and construction cost of the wharf. For general-purpose and multi-purpose ports, the investment is large and the utilization rate is low. The high-efficiency bucket gate machine has low requirements on the wharf and low cost, and is suitable for different ship types and different cargo types. In addition, the hanging idler-type discharge system is adopted to avoid the impact of large-flow materials on the ground belt conveyor and reduce the use and maintenance costs of the equipment.
(3) Promote the technological progress of the industry.
The 55 t 50 m gantry crane has broken through a series of key core technologies, and combined with the technical parameter requirements of the product, the high-efficiency gantry crane has been designed and developed from the aspects of structure, technology, safety, intelligent control and industrialization. This product will lead my country’s port operation equipment manufacturing industry to develop in the direction of large tonnage, large scale, intelligence, environmental protection and energy saving, promote the upgrading of traditional equipment and industrial structure adjustment, and realize the leap-forward development of the industry. In addition, this product greatly enhances the international competitiveness of my country’s port operation equipment, and provides large-scale, efficient and intelligent operation equipment for ports under the “Belt and Road” initiative.

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