Opening report of mechanical design paper
Title: Design of upward lime belt conveyor
I. Basis and significance of the project
Belt conveyor is a kind of continuous transportation equipment, which is mainly used in heavy industry departments such as metallurgy, mining, electric power, building materials, transportation and so on to transport a large number of powdery, massive and packaged articles, such as ore, coal, sand and so on. Because the belt conveyor has the characteristics of long distance, large capacity and continuous transportation, it has become the most ideal efficient continuous transportation equipment in coal mines. Belt conveyor is reliable, easy to realize automation and centralized control, especially suitable for high-yield and high-efficiency mines.
Because the belt conveyor is a friction-driven machine, it transports materials in a continuous way. By using it, the material conveying process from the initial feeding point to the final discharging point can be formed on a certain conveying line. Therefore, choosing the design of belt conveyor as the topic of graduation project can cultivate our ability to solve practical engineering problems independently. Because cargo lime is widely used now, it is necessary to design an upward lime belt conveyor.
Second, the research status and development trend at home and abroad (including literature review)
1, Research on the Development of Belt Conveyors Abroad
The research on belt conveyor abroad includes many aspects, such as the optimization theory of conveyor start-up, the development of transverse vibration theory of conveyor belt, the research of glue conveying device, the research of glue conveying device, the research of unloading trajectory and material flow state, etc. The research and development in the specific days are as follows:
The best theory of S-curve start This study started with 198 1 Australian Federal Scientific and Industrial Research Organization, and optimized the start of the conveyor belt to minimize the instantaneous stress. At start-up, the S-curve will produce predictable dynamic stress on the conveyor belt.
With the development of conveyor belt vibration theory and the study of orthotropic thin plate theory, the vibration and bending phenomena of moving conveyor belt have been explained mathematically for the first time, which provides an accurate method for predicting the vibration energy of the return section of belt conveyor. The solution of the fourth-order partial differential equation is obtained and applied to a specific elastic boundary called a thin plate. A method is obtained, which needs to apply different special boundary conditions to predict the vibration forms of wire rope core conveyor belt and fabric belt in the transportation section and return section.
Research on Rolling Loss At the end of last century, a new research was conducted to predict the friction of long-distance and turning conveyors.
Newcastle University has studied the influence of materials and conveyor belt bending and published many research results. Others have also published their own research results, which are mainly reflected in their understanding of the influence of bending and rubber characteristics related to rolling collapse loss and the complex situation related to collapse loss.
There are many dynamic analysis methods to solve the elastic stress propagation problem of conveyor belt, including wave model, mass spring model, boundary element model and finite element/differential method. Each method has its own mathematical foundation. For example, the wave model method needs to consider the Fourier components of all stress waves, while the solution of the mass spring model depends on the amplitude of each mode that produces stress. For the finite element model, if a large number of operations are used to simulate the stress, if the boundary of the element is wrong, problems may occur, and the modulus of the element becomes very critical. The application of wave model needs more mathematical basis, while the mass spring model is easier to be processed by a computer with high speed and large storage capacity.
Table 1 Main technical indexes of foreign belt conveyors Zh_ _sxd =
Table 1 Main technical parameters of foreign belt conveyors.
3 million ~ 5 million t/a high-yield and high-efficiency mines abroad @_jLSym Rn
& gtg main parameters
Along-trough telescopic belt conveyor
Fixed strong belt conveyor for alleys and inclined shafts
Distance/meter
2000~3000
﹥3000
Tape speed/ms-1
3.5~4
4 ~ 5, 8 at most.
Transport capacity /t.h- 1
2500~3000
3000~4000
Total driving power/kW
1200~2000
1500 ~ 3000, at most 10 100.
2. Research on the development of domestic belt conveyor.
There are many varieties and types of belt conveyors produced in China. During the Eighth Five-Year Plan period, through the implementation of the national one-stop project of "fully mechanized mining equipment with a daily output of 10,000 tons", the technical level of belt conveyor has been greatly improved, and the key technology research and new product development of high-power long-distance belt conveyor for coal mines have made great progress. For example, the complete set of equipment for long-distance belt conveyor with large inclination angle and the retractable belt conveyor with high yield and high efficiency have filled the gap in China. The key technologies of belt conveyor deceleration and its main components have been studied and developed theoretically, and a variety of soft start and braking devices and programmable electric control devices with PLC as the core have been successfully developed. The drive system adopts variable speed hydraulic coupling and planetary gear reducer. At present, the main technical characteristics of belt conveyors used in coal mines in China are shown in Table 2.
Table 2 Main technical indexes of domestic belt conveyor
Table 2 Main technical parameters of belt conveyor in China
Main parameter
Along-trough telescopic belt conveyor
Fixed strong belt conveyor for alleys and inclined shafts
Distance/meter
2000~3000
﹥3000
Tape speed/ms-1
3.5~4
4 ~ 5, 8 at most.
Transport capacity /t.h- 1
2500~3000
3000~4000
Total driving power/kW
1200~2000
1500 ~ 3000, at most 10 100.
3, the gap between domestic and foreign belt conveyor technology
Gap 1: technical performance comparison
The main performance and parameters of belt conveyor in China can't meet the needs of high-yield and high-efficiency mines, especially the key components and functions of belt conveyor along the trough, such as self-moving tail, high-efficiency belt storage and tensioning device, which are far from foreign countries. | S _ & gt(YWu9 from the above main technical indicators of belt conveyors at home and abroad:
1. The maximum installed power of various conveyor belts is far lower than that of foreign countries.
2. The belt speed is limited by the idler speed, and the belt speed of belt conveyor in China is at least 1m/s (4m/s in China and 5m/s abroad).
3. Transport capacity The maximum transport capacity of belt conveyor in China is 3000 t/h, which has reached 5500 t/h abroad.
4. The transportation length of the working face along the gateway is 3000 meters at home and 7300 meters abroad.
5. The maximum conveyor belt width in China is 1400 mm, and that in foreign countries is1830 mm..
6. Self-moving tail =nr_YjxlC~ Nowadays, efficient work requires the tail of conveyor to move quickly with the rapid advancement of working face. The domestic automatic tail mainly depends on imports, so the gap is far from perfect.
7. High-efficiency belt storage tensioner The closed belt storage structure and winch are mainly used in China. The tensioning trolley is easy to derail and the conveyor belt is easy to run off. When the conveyor belt expands and contracts, the idler trolley does not move by itself, so it needs to be moved manually, which is troublesome to maintain. Foreign countries adopt advanced open belt storage device and high-precision automatic tensioning equipment with large torque and long stroke, and the idler trolley can automatically expand and contract with the conveyor belt. The conveyor belt is easy to deviate and will not derail.
8. There are few types of conveyors in China, with single function and limited application scope, which can not give full play to their performance. Moreover, because the geological conditions of coal mines in China are very different, it is necessary to arrange new special conditions in the transportation system, so it is necessary to develop special conveyors.
Gap 2: Differences in core technologies
1. Dynamic analysis and monitoring technology
Dynamic analysis and monitoring technology is the key technology of long distance and high power belt conveyor, which restricts the development of large belt conveyor. In the research of belt conveyor, the rigid body theory is used to analyze and study the calculation method and design specification in China. In fact, the conveyor belt is viscoelastic, and the dynamic response of the conveyor belt to the starting and braking force of the driving device is a very complicated process, which cannot be explained and calculated simply by rigid body mechanics. Therefore, China adopts a high safety system for conveyor belts.
The dynamic design method and application software of belt conveyor are developed, and the dynamic tension of conveyor is dynamically analyzed and monitored on large conveyor, which reduces the safety system of conveyor belt, greatly prolongs the service life and ensures the reliability of conveyor operation, thus making the design of large belt conveyor reach the highest level and greatly reducing the equipment cost of conveyor, especially the conveyor belt cost.
2. Controllable soft start technology and power balance technology.
For the belt conveyor with long production distance, we need to use soft start to reduce the braking tension of the conveyor, especially when multiple motors drive it. However, it is also necessary to study soft start, which is divided into slow start and fast start to reduce the impact on the power grid; However, the starting acceleration should be controlled at 0.3 ~ 0. 1 m/, so as to solve the problem of belt speed synchronization between the bearing belt and the driving belt and the surge phenomenon of the conveyor belt and reduce the impact on the components. The power balance between motors should also be controlled and the balance accuracy should be improved. China has solved the problems of starting, power balance and synchronization of long-distance belt conveyor, but its adjustment accuracy and reliability are still far from those of foreign countries. In addition, the long-distance high-power belt conveyor requires not only the belt speed of transporting coal, but also the belt speed of belt inspection. Although the variable speed hydraulic coupling has realized soft start and power balance, it is necessary to develop a stepless hydraulic speed regulating device suitable for long distance.
Gap 3: Control System Gap
1. There are variable speed hydraulic coupling and hard gear reducer in China, and there are many driving modes abroad, such as BOSS system and CST controllable transmission system, which have high control accuracy.
2. Monitoring device Domestic conveyors adopt high-grade programmable controllers to control the working process of conveyors, such as startup, normal operation and shutdown. This programmable controller has no automatic access device, no fault diagnosis and query functions. Advanced program software and integrated power relay control technology, as well as a complete automatic monitoring system for data acquisition, processing, storage, transmission, fault diagnosis and inquiry, have been developed by using high-grade programmable controller PLC abroad.
3. Conveyor protection device Compared with foreign countries, China's conveyor protection device is in a blank state in many aspects, that is to say, the protection device designed abroad is not available in China at present. For example, many new monitoring devices have been developed for foreign belt conveyors, such as temperature monitoring systems for driving rollers, steering rollers and idler groups, smoke alarm and automatic fire extinguishing devices, longitudinal tearing and joint monitoring systems for fiber woven conveyor belts, and automatic measurement systems for explosion-proof electronic belt scales. Our country not only does not have these developments, but also the reliability, sensitivity and life span of these basic protections are very low.
Gap 4: the gap between reliability and life.
1. The highest tensile strength of the fabric full-core flame-retardant conveyor belt produced in China is 2500 N/mm, and that of foreign countries is 3150 N/mm.. The maximum flame-retardant conveyor belt with steel wire rope core is 4000 N/mm, which is 7000 N/mm abroad. \ [Email? Protected] _l_xWG
2. Strength of conveyor belt joint The strength of conveyor belt joint in China is 50% ~ 65% of that of master belt, and it can reach 70% ~ 75% of that of master belt abroad. Trifluoromethane hydroxide
3. Service life of idlers Compared with foreign countries, the existing idler technology in China has short service life, low speed and large resistance, while the new oil-filled idlers used in the United States and other countries have small running resistance, and the bearings are lubricated with thin oil, which greatly improves the service life of idlers, and can be used as high-speed idlers in belt conveyors, with wide application and remarkable economic benefits. The service life of conveyor idlers in China is 20000h, while that of foreign idlers is 50000 ~ 90000h, and that of domestic idlers is only 30% ~ 40% of that of foreign products. J_\z-_Y O_
4. The service life of the conveyor reducer is 20000h at home and 70000h abroad. _P`uU_o(？
5. The reliability of belt conveyor is poor when it runs up and down. a & lt+O`4___
4. Now the development trend of belt conveyor.
1. Equipment enlargement and transportation capacity improvement In order to meet the needs of high-yield and high-efficiency intensive production, the transportation capacity of belt conveyor should be improved. Long distance, high belt speed, large capacity and high power are the inevitable trend of future development, and also the development direction of high-yield and high-efficiency mine transportation technology.
2. Improving the performance and reliability of components The operation rate of equipment mainly depends on the performance and reliability of components. In addition to further improving the performance and reliability of existing components, new technologies and components such as high-performance controllable soft start technology, dynamic analysis and monitoring technology, high-efficiency belt storage device, fast self-moving tail and high-speed idler should be continuously developed to further improve the performance of belt conveyor.
3. Expand the function, expand the function of one machine for multi-purpose transportation of personnel and materials or two-way transportation, so that one machine can be multi-purpose and maximize economic benefits. Develop special belt conveyors, such as curved belt conveyors, large inclination or vertical lifting conveyors.
Third, the research content and experimental scheme
General belt conveyor is composed of conveyor belt, idler, roller and driving, braking, tensioning, reversing, loading, unloading, cleaning and other devices. I designed the ascending lime belt conveyor this time, which belongs to the general belt conveyor. Mainly calculate and select the type of conveyor belt, idler type, idler type and tensioner.
According to the specific situation of the place of use, user requirements or conveyor types, the overall layout of the conveyor is carried out. It mainly includes the determination of the form, quantity and installation position of the driving device, the form and installation position of the tensioning device, the layout of the nose and tail, the loading position and form, the type and position of the cleaning device, etc. The conveyor belt is wound around the driving roller and the tail reversing roller to form an endless closed belt. The upper conveyor belt and the lower conveyor belt are supported on the upper idler wheel and the lower idler wheel respectively. The tensioning device ensures the tension required for the normal operation of the conveyor belt. When working, the driving roller drives the conveyor belt to run through friction. Materials are loaded on the conveyor belt and move with the conveyor belt. Usually, the material is transported by the overhead conveyor belt and unloaded when the conveyor belt changes direction around the head drum. When necessary, a special unloading device can be used to unload at any position in the middle of the conveyor.
Four. Objectives, main features and work progress
When researching, designing and applying the target belt conveyor, we should maximize the efficiency of the belt conveyor. With the continuous development of belt conveyor, its design theory and development achievements basically meet the needs of mining industry. We use modern computer technology, combined with the actual position and theory, to design a better and more distinctive belt conveyor. Belt conveyors are widely used, so we need to pay more attention to safety devices and design conveyors with more satisfactory performance and quality according to market demand.
The upward lime belt conveyor is a conveyor belt-assembly line-conveyor belt machine, which is driven by friction and conveys materials in a continuous way. This kind of conveyor is mostly used in ground coal preparation plants and underground main conveying channels. Through it, we can transport materials from the initial feeding point to the final unloading point, and its transportation route is adaptable and flexible. The length of the line can be as short as 10 meter and as long as tens of kilometers, and it can also be installed in small tunnels or even erected on dangerous ground for classes. For modern industrial enterprises, this is an indispensable equipment.
Work schedule
1. Consult relevant materials, translate foreign materials (more than 6,000 words), and write the opening report for 20xx.12.27 ~ 20xx.01.21.4 weeks.
2. The calculation of motion and dynamic parameters is 20xx.03.2 1 ~ 20xx.04.032 cycles.
3. The general assembly drawing is designed from 20xx.04.04 to 20xx.04.24 for 3 weeks.
4. The strength and selection of main parts shall be calculated from 20xx.04.25 to 20xx.05.08 for 2 weeks.
5. Draw parts and assemblies for 2 weeks from 20xx.05.09 to 20xx.05.22.
6. Write design calculation instructions (graduation thesis) for 20xx.05.23 ~ 20xx.06.052 weeks.
7. Graduation design review and graduation defense for 20xx.06.06~20xx.06.23 2 weeks.
Verb (abbreviation of verb) reference
[1] Sun Huan et al., mechanical principle. Beijing: Higher Education Press, 200 1.
[2] Pu et al. Mechanical Design. Beijing: Higher Education Press, 200 1
[3] Editorial Committee of Design and Selection Manual of Transport Machinery. Handbook of design and selection of transport machinery. Beijing Chemical Industry Press 1999
[4] Fan Zuyao editor. Handbook of modern mechanical equipment design. Beijing: Machinery Industry Press, 1996.
[5] Xu Hao. Manual of Mechanical Design (4th Edition). Beijing. Machinery industry press. 199 1.
[6]s higley J. E, UICHER J.J. Theory of Machine and Mechanism. New york: McGraw-Hill Books, 1980.
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