1、英文原文Mathematical model of electric hydraulic and powered support control system at a plough mining faceZHANG Wei, HAN Xiao, SUN Jing-jingSchool of Mechanical Electronic and Information Engineering, China University of Mining & Technology, Beijing 100083, ChinaAbstract: Given the actual working of a
2、fully mechanized plough at a mining face, we have proposed a formula for running constraints between powered supports and a coal plough under assumed geological conditions of the coal face and, on this basis, established an automatic control model of powered supports for the coal plough face. We int
3、roduced the working principle of the powered support control system of the plough at the mining face. We established three advanced characteristics of this control system: response speed, reliability and easy maintenance of the system. .As well, we briefly introduced, the principal function of prima
4、ry and subordinate controllers and the realization of the communication system by a Single Bus. Ten controllers were constructed and tested in our laboratorium. The results show that the control model is practical and meets actual conditions. It provides a theoretical basis for designing a computer
5、control system for a powered support system of a plough at a mining face. Key words: plough mining face; powered supports; constraints; automatic control model1 Introduction More than six billion tonnes of thin seam mineable reserves with a shearing height of 0.71.3 m, are available in China, which
6、is about 18 percent of the total reserves of our country. With a thin seam shearer, 0.8 m is the lowest mining limit because of its structural restrictions. Furthermore, the shearer is inconvenient for workers to operate and maintain and workers have to work under conditions of extremely low space w
7、ith this machine1. Therefore, coal ploughs become major pieces of equipment for mining thin seams. However, the space of a thin seam is narrow and small. Although workers do not need to work following the coal plough, they still need to operate the powered support system. Not only is there a hidden
8、safety problem, but also the speed of moving the supports artificially falls far short of the speed of the coal plough, seriously restricting the efficiency and output at the mining face2 .The powered support system is the support equipment but it is also one of the major pieces of equipment at a fu
9、lly mechanized coal face. With the development of electronic computers and automatic control technology, the automation of mining equipment is continually improving and simultaneously the electric hydraulic control technology of powered support systems is also developing. The electric hydraulic cont
10、rol system of powered support can not only control the action of the support system automatically, but also realize adjacent or long-range control. Thus the potential of an automated mining face, operated without human hands, may be realized. Therefore, its application to a fully mechanized coal fac
11、e should be explored for its important implications32 Automatic control model of powered support system and its constraints on the coal plough 2.1Constraints between powered support system and coal plough The coal plough and the shearer are two different mining machines. Compared with a shearer, coa
12、l ploughs are mainly applied with thin seams. Their structure is simple, the cutting depth is thin and the draught speed is quick. Therefore, the constraints between powered supports and a coal plough, which will be discussed by us, are different from that between powered supports and a shearer. We
13、assume the following geological conditions to prevail at the coal face: the hardness coefficient is below 21, the dip angle is small and the thin ceiling of the seam is steady4 .The following mechanical pieces of cutting equipment are provided for the coal face: a coal plough, a flexible chain conve
14、yor and powered supports. Let the letter “p” represent the cutting depth of the coal plough (100 mm) and “q” the stroke of the cylinder (600 mm) of the support pusher. The constraints among the coal plough, powered supports and the flexible chain conveyor will be discussed under the assumptions list
15、ed above. As shown in Fig. 1, when the coal plough is mining coal by drawing back and forth along the face, the system of two supports push the conveyor behind the plough and each of these supports pushes the conveyor (mm), which is per stroke. The scraper conveyor bends along a certain curve. Suppo
16、rts manage to push the conveyor to the cutting depth p (mm) after having pushed the conveyor two times when the coal plough finishes mining a draught once along the coal face. Supports manage to push the conveyor a distance of half stroke after the plough has mined integer times along face. The supports that have finished a half stroke perform a lower-advance-set operation every other support. The mention above is the constraints between supports and the
