Technical guidance for the hottest metallurgical c

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Technical guidance for metallurgical cranes (1)

as a key and important equipment necessary for the safe and normal production of the metallurgical industry, the reliability, safety and progressiveness of metallurgical cranes have always been highly valued by people. However, restricted by the traditional metallurgical process, the domestic metallurgical cranes in the 30 years before the reform and opening up basically made some small-scale improvements and development under the mode of the former Soviet Union. With the deepening of reform and opening up and the introduction of a large number of foreign advanced technologies, modern metallurgical cranes have also undergone great changes. Based on the improvement of metallurgical process in domestic metallurgical enterprises and the use requirements of end users, this paper gives some views on the development trend of metallurgical cranes

metallurgical cranes generally refer to casting cranes, charging cranes for material boxes, slab handling cranes, steel coil clamp cranes, disk cranes and other bridge cranes serving metallurgical plants with higher working levels. Due to the change of steel-making, billet (ingot) and steel rolling process in metallurgical enterprises, traditional metallurgical cranes such as ingot removal crane, soaking pit clamp crane, rigid material scraper crane, open hearth bridge charging crane and soaking pit cover lifting crane have been gradually phased out. No further analysis will be made here. The development trend of several cranes widely used in metallurgical enterprises will be preliminarily analyzed, and the price will also drop

1 general development trend

1.1 one of the main trends in the development of modern metallurgical cranes is the large-scale lifting capacity and high-speed working speed. With the development of society, the requirements for metallurgical enterprises are gradually increasing, which is not only reflected in the quantity requirements of metallurgical products, but also in the quality and variety of metallurgical products, As the increase of social demand has promoted and promoted the technological transformation and technological progress of metallurgical enterprises, the application of large-scale converter, continuous casting and rolling technology has put forward higher requirements for the large-scale and high-speed of metallurgical cranes. Now, a simple statistics is made on the development of casting cranes in major domestic metallurgical crane manufacturers: it can be seen from the above table, The lifting speed and weight of the main hook have been greatly improved in the past 50 years

1.2 the hoisting and operating mechanisms all adopt speed regulation system. As early as the 1970s and 1980s, with the development and maturity of AC speed regulation technology, foreign famous crane manufacturers have launched the commitment of speed regulation of each mechanism. The speed regulation range varies with different speed regulation modes. At present, the stator voltage regulation and variable frequency speed regulation system is widely used in the design. The stator voltage regulation is the most important part of the lifting mechanism, and the variable frequency is the most important part of the operating mechanism

the mechanism has the following obvious advantages after speed regulation:

a) the mechanism has stable starting and braking. When the mechanism is started or braked at only 1/10 or 1/20 of the normal speed, the lifted object runs smoothly, which is particularly beneficial to the crane for lifting and casting the light lined ladle of fire suit and 2 carbon oxide absorption mask

b) it can effectively reduce the wear of brake block

c) the lifted object can be accurately positioned

d) reduce the impact on the metal structure (bridge or trolley frame) and transmission system, and prolong the service life

e) it can effectively improve the working environment of operators

f) reduce the impact of starting on electricity

the use of speed control system also brings the following problems:

a) the cost of crane increases

b) the technical level of maintenance electricians is required to be high. Although the adoption of speed regulation system will increase the equipment cost and increase the difficulty of maintenance, with the progress of technology, the cost of speed regulation system is also gradually reduced, and its advantages are more and more obvious. After the speed regulation of the system, the change of its working condition has laid a solid foundation for its development

1.3 monitoring and sensing control technology is widely used, and its performance and reliability are greatly improved. With the progress of science and technology, various monitoring and sensing control technologies have been widely used in metallurgical cranes, which greatly improves the service performance of cranes, and makes metallurgical cranes from the previous simple material handling tools to the current comprehensive transmission equipment of logistics and information flow

1.3.1 weighing device: a digital weighing device is set on the casting crane, the small display screen is placed in the cab, and the large display screen is set under the main end beam, facing the ground, so that the weight of molten steel in the steel ladle can be displayed at any time. This data is connected to the computer room, on the one hand, the daily output can be accumulated, on the other hand, the continuous slab size can be developed comprehensively, harmoniously and continuously according to the connection The number of blocks determines the amount of steel that the steel drum should hold to reduce waste. With the application of various large-scale and high-precision electronic scales, metallurgical cranes can complete the functions of output statistics, overload power failure and alarm while handling goods

1.3.2 fault display, recording and printing devices in iron and steel enterprises with continuous production, time is money. It is hoped that the maintenance time will be reduced to the minimum after the crane breaks down. The fault display device can display the names of the parts and components that are in fault on the display screen in the cab, so that the maintenance personnel can immediately know the location of the fault, which can greatly shorten the maintenance time. The list of electrical and mechanical parts prone to failure shall be made by the owner. The crane manufacturer shall set fault display points according to the owner's requirements. Once the monitored parts fail, they will be displayed on the screen to avoid more serious faults. In addition to the display function, the device also has the functions of recording and printing, so as to find out the fault causes and implement the needs of verification

1.3.3 II. The position of the lifting appliance of the three-dimensional positioning device in the space can be displayed on the display screen in the cab through the device, and the positioning accuracy can be controlled below ± 10mm, which can meet the process requirements of various automatic operation lines. The driver can visually determine whether the lifting appliance or object has reached the position that the object should reach through the numbers displayed on the display screen, which can greatly shorten the lifting time and avoid the shaking of the object, which can effectively improve the production efficiency

1.3.4 in the past, in order to prevent the collision between two cranes, only limit switches and buffers were installed. The existing laser or radar anti-collision devices. One crane is equipped with a launching device, and the other crane is equipped with a receiving or reflecting device. When the preset spacing is reached, an alarm will be sent to avoid collision

1.3.5 the safety brake is used to lift important objects, such as nuclear raw materials, liquid metals, generator rotors of large hydropower stations, etc., and the drum of the main lifting mechanism of the crane is equipped with a safety brake. One pair, two pairs or even three pairs of pads can be set on the flange on one side of the drum according to the requirements of braking torque, which are controlled by a specially set hydraulic station. When starting, the safety brake is opened first, and the service brake set on the high-speed shaft is opened later. When braking, the service brake shall be applied first, and the safety brake shall be applied after a delay of several seconds. The function of the safety brake is to ensure the safety of the hoisted object when any transmission part in all transmission chain links between the service brake and the safety brake is damaged or broken. It is not only the development direction of modern metallurgical cranes, but also the goal of designers for large power battery enterprises to properly apply various monitoring and sensing technologies to cranes and realize wired or wireless control of metallurgical cranes

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