Present situation, characteristics, manufacturing

2022-08-02
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Since the reform and opening up in the 1980s, China's economy has developed rapidly, and a large number of ports and power plants have been built and put into use. Many national key projects have introduced foreign advanced technology and equipment. Qinhuangdao port, Rizhao Port, Qingdao Qianwan port, Lianyungang port, Ningbo port, Tianjin port, Huanghua port, Guangzhou Xinsha port, Guangzhou Xiji port, Zhanjiang port, Shanghai port, Baosteel and other large bulk material loading and unloading ports have been successively built. The main cargo handled at these bulk ports is coal or iron ore. A large number of old power plants no longer use bulldozers, loading and unloading bridges, forklifts and other low-efficiency transportation equipment, and all new power plants have adopted efficient continuous transportation equipment. Domestic users use foreign advanced equipment by means of import and cooperative manufacturing. Some domestic equipment is also exported to other countries. Bulk material machinery and equipment have made great progress. A large number of foreign companies have joined China's infrastructure. During this period, large-scale equipment from Germany, the Netherlands, the United States, Japan, France, the United Kingdom and other countries were introduced. It mainly includes large grab quay bridge, bucket wheel stacker reclaimer, large ship loader and the whole bulk cargo handling system, which also promotes the design and manufacturing level of such equipment in China. At present, there are twoorthree manufacturers that have produced large grab quayside bridges in China. More than ten manufacturers have produced stacker reclaimers, and fourorfive have designed and manufactured stacker reclaimers for a long time. These manufacturers have contributed to the development of the national economy

characteristics of bulk material machinery and other general machinery

bulk material machinery is a large-scale mechanical equipment for single piece and small batch production. Most products are designed and manufactured for a certain project. It is not like the automobile manufacturing industry that the relative form parameters of products are relatively fixed, and a large number of products are cut out. Therefore, there are certain differences in the design and manufacture of equipment among different users. Because of this, the equipment will inevitably have some problems and deficiencies. To improve the comprehensive quality of the equipment, the product must be designed in strict accordance with the product specifications or the provisions of the contract from the design. In the manufacturing stage, strict manufacturing process shall be formulated to make the equipment meet the most perfect requirements as far as possible through careful and careful design and calculation. According to international practice, the management of enterprises in all aspects should be managed and required in accordance with ISO 9000 series standards

design and manufacturing technology of bulk material machinery

major accidents of bulk material machinery mainly refer to equipment collapse during installation and use, large cracking of local steel structure of equipment, fracture of reducer shaft of important mechanism, resulting in casualties, etc. To avoid the occurrence of such incidents, it is necessary to strengthen management from many aspects. From the initial selection, design, installation, use and maintenance, etc

correct design is an important guarantee for equipment quality. The design of bulk material machinery is a relatively complex design process, because the functions, capabilities and parameters of the equipment often change with different users. Therefore, its mechanism and structure change accordingly. This change increases the difficulty of design work. In general design, iso5049 and FEM standards are used for bulk material mechanical design. The design of steel structure is an important link in the design of bulk material machinery. Compared with the steel structure of other machinery, the details of the steel structure of bulk material machinery vary, and the design of the steel structure of bulk material machinery is a complex and meticulous work. It is often in small details that design errors lead to major accidents. The influence of fatigue stress on the structure should be fully considered at some parts of alternating load, and the actual stress should be appropriately reduced at the parts with stress concentration

reliability of control system. Now the control system is generally controlled by PLC, and the reliability has been greatly improved. The key to the electrical system is the reliability of the execution system and the detection system. The detection system includes various position detection, speed detection and other primary instruments 149 cross linked polyethylene (PE-X) pipe system table and limit switch for cold and hot water. The executive system mainly refers to the frequency converter, contactor and other electrical components

avoidance of faults or errors of bulk material machinery

some problems often occur in the design and manufacturing process of bulk material machinery, and these problems are often found in the installation and use process. In order to avoid and reduce the occurrence of such problems, this paper lists some common problems

ability parameters, motion parameters and geometric parameters. There are many parameters of bulk material machinery, such as belt conveyor capacity, bucket wheel stacker reclaimer capacity, ship loader and ship unloader capacity, belt speed of various equipment belt conveyors, belt width of various equipment, pitching speed and pitching angle of various equipment, slewing speed and slewing angle, crane traveling speed range, etc. These parameters should be mutually adapted to the actual position requirements of the whole system and the site. Whatever the characteristics of wide measurement limitation, high precision and fast response, the parameters should not be too large or too small. Too large and too small are unfavorable to the system and equipment. The problem of parameters actually includes two aspects: overall design and equipment design. If the equipment parameters are determined unreasonably during equipment selection, the products that must be manufactured are also products with unreasonable parameters

the above parameter problems often lead to errors in the overall or equipment design, which eventually leads to the equipment being imperfect after being put into operation. On Stacker Reclaimer equipment or ship loader equipment, the rotation angle cannot reach the actual required parameters due to the limitation of geometric position. This will make the actual application function of the equipment fail to meet the process requirements, and will cause great economic losses to users and manufacturers. On the belt conveyor or bulk material machinery, such as ship loader, bucket wheel stacker reclaimer and other equipment, improper design of the geometric position relationship of the belt conveyor chute will lead to material blockage, belt deviation, scattering and other failures

power parameters of each mechanism. The power of different equipment and mechanisms has different calculation methods, and its specific value should also be appropriate in actual selection. Too high or too low parameters are unfavorable to the equipment. Many users are willing to pursue higher power because they are worried about insufficient power. In fact, too much power will increase the operating cost of the equipment. More importantly, after the power increases, the load of some mechanisms will also increase in case of overload. For example, when the bucket wheel mechanism or rotary mechanism of the bucket wheel stacker reclaimer is overloaded, the load on the steel structure of the whole machine will increase, which will directly affect the strength or stiffness of the steel structure of the equipment. Therefore, it is not recommended to increase the margin of driving motor power of each mechanism of the equipment too much

institutional errors. Mechanism errors may occur in the design of the equipment, such as incorrect calculation of pulley magnification in the design of pitching or hoisting mechanism and cantilever telescopic mechanism; The drive or transmission mechanism has redundant constraints, resulting in shaft failure; Fatigue failure of shaft parts due to calculation error; Gear parts have broken teeth due to insufficient strength in design; The standard reducer is too small and has short service life; The first stage transmission gear of the belt conveyor driving device has broken teeth and shaft; The form or mechanism scheme determined by some institutions is not reliable, resulting in frequent failures, etc. During the installation phase, it will be found that the mutual installation size or shape is wrong, which makes it impossible to install. For important pin shafts with rotating devices, there are usually sliding bearings that need to be lubricated. Special attention should be paid to the installation angle of the pin shaft. The wrong installation angle will make the angle position of the bearing that needs to be lubricated not greased

structural failure. The so-called structure refers to the components welded by steel plates or shaped steels, which are used to support the main body of equipment or some components, and to accelerate the transformation and upgrading of traditional industries. The structure of these supports is generally composed of box girder or I-beam. Now, most enterprises use foreign advanced finite element software for strength calculation in steel structure design. Great progress has been made in the design means. Generally, the continuous straight section of the main structure of the equipment is less prone to strength problems such as cracking, but it is prone to failure at discontinuous positions, such as fracture, open welding, fatigue cracking, etc., especially at the bending point of the beam, the force transfer point, and the connected stiffeners or gratings. In the process of design and manufacturing, special attention should be paid to the local treatment of steel structure design and force transmission. There are many major failures or accidents that occur in the local part of the beam or at the transfer point of the force. In the calculation, it is often difficult to simplify the mechanical model close to the actual structure or the force transfer point. The established mechanical model and mathematical model should be as close to the actual situation as possible. Therefore, the local part of the beam should be carefully analyzed. In addition, the bending radius of the transition section of non straight beam should be taken as large as possible, because there is a certain degree of stress concentration in this section, and the stress here is much larger than that in the non bending section. The smaller the bending radius, the greater the stress concentration. When the fault occurs at important parts, major accidents such as equipment overturning and fracture of main stress-bearing parts will occur. Therefore, special attention must be paid to the design and calculation of structural members, especially the local design of steel structures

control and drag. As modern mechanical equipment control and drive systems adopt more imported or joint venture products, the failure rate of equipment control and drive systems is relatively small, and its main manifestation is the reliability of all primary detection instruments. Such as the reliability of various limit switches, various encoders, and the mechanical connection of the detection system. It does show in the design, and then look for inspiration from our material library, mainly whether the control and protection system is complete and reasonable. Whether the layout position of various panels and cabinets is reasonable, and whether the direction of various cables is reasonable and meets the specification requirements

auxiliary structural members are equipment safety protection facilities, such as walkways, ladders, railings, etc. Because it is not the main stress-bearing part, it is easy to be ignored in the design and manufacturing stage, so that a certain number of auxiliary steel structural parts are found to be inappropriate in size, installation position and assembly mode, ladder handrail and walking platform do not meet the requirements of Safety specifications and standards, and the welding quality during field welding and installation is unqualified. Such problems need to be corrected on site or checked and corrected on site

limited by space, here are just some problems. More problems still need to be accumulated and summarized in daily work practice. (end)

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