放顶煤液压支架设计【含CAD图纸+文档】
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附录A 摘要:根据综采工作面实际工作情况,我们提出了采煤工作面液压支架和刨煤机两者运行关系的一个公式,并在此基础上,建立了工作面液压支架和刨煤机的自动化控制系统。我们介绍了采煤工作面液压支架控制的系统工作原理。我们归纳了本控制系统的三个参数:反应速度,可靠性和易维护性。同样,我们简要介绍了它的主控制器与附属控制器和由单总线实现的通信系统。我们实验室建造和测试了10个控制器。结果表明,该控制模型是可行的,符合实际情况。它为长壁工作面的液压支架计算机控制系统的设计提供了理论依据。关键词:长壁工作面,液压支架,参数,自动控制1. 引言在我国采高0.7-1.3米的薄煤层可开采的储量超过6亿吨,大约占我国总储量的百分之十八。因为薄煤层采煤机结构的限制,0.8米是采煤机最低开采高度,而且,这么低的空间下采煤机也不便于工人操作和维护。因此,刨煤机成为薄煤层开采的主要设备。然而,薄煤层工作面空间狭小。虽然工人不需要在刨煤机后工作,但他们仍然需要操作液压支架系统。这不仅是一个安全隐患,而且移架的速度远未达到的刨煤机速度,严重制约着综采工作面效率和产出 2 。液压支架不仅是支护设备,但它也是综采工作面的一个重要设备。随着电子计算机和自动控制自动化技术的发展,采矿设备的不断改善,电液控制技术也将在液压支架上逐步应用。电液控制系统不仅可以自动控制液压支架的动作,而且还实现邻架控制或远程控制。因此,综采工作面的自动化,完全无人化,完全可以会实现。所以,综采工作面的自动化成了应探讨的重要问题 3 。2. 液压支架自动化控制系统模型及刨煤机的约束参数2.1液压支架和刨煤机之间的制约关系 在刨煤机和采煤机是两个不同的采煤设备。同采煤机相比,刨煤机主要适用于薄煤层。其结构简单、截深小、牵引速度快。因此,我们将讨论不同于采煤机的刨煤机和液压支架之间的制约关系,我们假定下面的采煤工作面地质条件良好:硬度系数低于21,倾角小,薄煤层的顶板稳定。下列是为采煤工作面提供的机械设备:刨煤机,刮板链式输送机和液压支架。字母“ P ”代表刨煤机截割深度(100毫米)和“ q ”是液压支架的推移距离(600毫米)。上面列出的是讨论刨煤机、液压支架和刮板链式输送机之间的制约关系所做的假设。图一表示的是刨煤机在工作面上利用往复运动采煤,两架液压支架在刨煤机后推移输送机,每个支架推移的距离是(mm),每程是。刮板输送机沿着某一曲线弯曲。液压支架推动刮板输送机两次后达到切割深度p (毫米)。当刨煤机在工作面完成一次截割。刨煤机在工作面上开采时间后液压支架能推移刮板输送机半程的距离。此液压支架完成比其他没有推移的支架一半推移行程。图一上文提到的就是液压支架和刨煤机之间的制约因素。为了获得液压支架和刨煤机之间的制约关系,变量和函数的定义如下:1) 综采工作面液压支架数在从左至右依次为: 1 , 2 , 3 , . , (n1), n;2) v:刨煤机速度,采煤速度; x:刨煤机采过距离,即从工作面左侧到刨煤机中心的距离(见图-1 ) 。刨煤机采过距离x转化为位移K可用液压支架数目来计算,这与刨煤机中心一致。假设t= ,且 = 0 ,其中V是速度的刨煤机(米/秒) ; b是两个相邻液压支架中心之间的距离(米) 。3) 方向是从左向右前进,反之亦然。刨煤机运动方向由变量y表示:4) 支架的动作定义为,可以表示单一动作,如升架,降架,移架和推动刮板输送机等等,它也可以代表由几个单一动作组成的联合动作,如降价,移架,升架,下脚标表示某个动作(i = 1 , 2 , 3 ) 。三种动作的符号的定义如下:f1: 动作1 (推移截深的一半); f2: 动作2 (推移一个截深距离); f3: 降架-移架-升架5) 定义的动作功能。当液压支架M执行动作,我们定义如下: M (4)其中,代号为“ ”是指操作。f1 K1::支架K1 动作1 (推移截深的一半) ; f2 K2:支架K2 动作2 (推移一个截深) ; f3 :支架降架-移架-升架这11个动作统一表示为:“ S ”的是刨煤机移动的距离(毫米)。当刨煤机在工作面往返采煤时液压支架首先执行动作f1和f2 ,动作执行完成半程后,执行动作f3。6) 相对距离,根据液压支架的数目,执行动作的液压支架Ki,刨煤机的中心K ,Ki=|KKi|。 Ki与刨煤机的中心有关(当位置已知)。Ki对于工作面是一个常量。我们从图二和条件三和Ki的定义得到:从表达式(2)、(5)、(6)我们可以得到:表达式(8)是液压支架和刨煤机制约因素之间的数学关系。它表达液压支架间的动作的关系,和刨煤机行程,刨煤机运行方向。支架Ki 刨煤机中心的距离没有变化,当开采时液压支架分别对应不同的刨煤机运动距离x执行3个不同的动作 。图二2.2液压支架和刮板输送机之间的制约因素 每个液压支架推移千斤顶与刮板输送机相连,由推移千斤顶推移刮板输送机。刮板输送机按照一定的曲线减少在运动时弯曲点的磨损。刮板输送机要保持灵活以减少半程的牵引阻力。2.3液压支架自动化控制模型实际上,方程(7)及(8)是支架位置自动化控制模型的表达式,其中刨煤机的行程( x或K)作为一个变量。由液压支架数目计算(支架数目K相当于刨煤机中心)位移K当刨煤机来回往复可以变化。以与刨煤机中心一致的液压支架K为基准,一套支架相对支架K的位置不会改变。把i,y带入公式(8),自动控模型可以描述为:1 )当刨煤机向右运动时,液压支架K - K1移动1 / P的行程,支架K - K2移动2 / P的行程;液压支架K-执行降架-移架-升架(在这一点上,支架完成了行程的一半) 。2 )当刨煤机向左运动时,支架K+K1移动1 / P的行程;支架K+K2移动2 / P的行程;支架K+执行降架-移架-升架(在这一点上,支架完成了行程的一半) 。K是由按键操作的液压支架的数目; K1 -是距正在执行动作的支架到支架K的距离 5-9 3. 系统的原理结构如图-3所示,每个液压支架都由附属控制器控制和形成一套电液控制附属系统。 COM端口的主要控制器及所有附属控制器连接到一个通信总线,它构成了综采工作面液压支架微机电系统 5 。图三1)系统的响应速度迅速:主控制器和附属控制器之间的通信,或中下级控制器是直接的,因为COM端口的主控制器和任何附属控制器都连接到单总线,因此从属控制器之间的响应速度迅速。2 )快速系统的可靠性:在一个单总线通信系统,如果主控制器或下级控制器故障整个系统将不会受到影响仍能够正常工作。除非控制器遭破坏,主控制器或下级控制器才受到影响,这种情况很少发生。单一通信总线系统是相当可靠的。3)系统维护:关掉电源后的主控制器或从属控制器的维修就可以执行了,附属控制器液压系统的可以维修和部件可以被替换。这种维修不影响系统正常工作,系统维护方便。4. 主控制器和附属控制器的功能和系统通信每台液压支架配备的附属控制器是电液控制系统的核心。附属控制器监测记录所在液压支架数据,如支架的动作等,翻译和编辑这些数据,并对支架发送控制命令 3 。综采工作面COM端口的主控制器和所有附属控制器连接到通信总线,可实现统一管理,并建立系统的控制参数。 该系统已通过单总线,连接不同的附属控制器到网络。附属控制器从单一总线发送和接收控制信号监测和控制所在液压支架的动作和之间实现控制。综采工作面主控制器初始化系统和设置参数,并从单一总线收集信号实现集中检查和系统的距离显示。5.结论 在这项研究中,我们已经提出了液压支架和刨煤机之间运行制约因素的一个数学表达式。我们建立了一个液压支架的自动控制模型并介绍了电液控制系统的基本原理,以及主控制器及附属控制器的功能。我们在实验室建造了十套从属控制器,实验表明,该控制模型符合实际要求。附录BMathematical 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 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 introduced 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 primary 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 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 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 with 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 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 fully 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 control 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 face 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, coal 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 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 conveyor 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 listed 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. Supports 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 coal plough.In order to obtain the constraints between supports and the coal plough, variables and functions are defined as follows:1)Number powered supports at the mining face from left to right: 1, 2, 3, , (n1), n;2)v: speed of plough, mining coal; x: displacement of plough, i.e., the distance from the left of the face to the center of the plough (see Fig. 1).The displacement x of the plough is converted into displacement K calculated by support number, which corresponds with the center of the plough. Suppose that t = , and = 0, where v is the speed of the coal plough (m/s); b is the distance between two centers of adjacent supports (m). 3)The direction from left to right is forward and vice versa. The direction of the plough movement is denoted by the variable y:4)The support acts are denoted by , which can represent a single action, such as setting the leg, lowering the leg, moving and pushing the conveyor and so on; it can also represent a combined action composed of several single acts, such as lower-advance-set. The subscript shows action i (i=1, 2, 3). The symbols of the 3 actions are defined as follows:f1: act1 (half of a cutting depth is pushed); f2: act2 (a cutting depth is pushed); f3: lower-advance-set operation.5)Define action function. When support M carries out action , we define: M (4)where the symbol “” means operating.f1 K1: support K1 act1 (half of a cutting depth is pushed); f2 K2: support K2 act2 (a cutting depth is pushed); f3 : support (lowing-advancing-setting;These 11 actions are expressed in a united way: where “s” is the moving distance of the plough (mm). 6) The relative distance, calculated by support number, between the support performing action i and the center of the plough is denoted by K , where Ki=|KKi|. Ki is related to the position of the center of the plough (confirmed when its position is known). Ki is a constant for a certain face. We know from Fig. 2, condition (3) and the definition of Ki that: Eq.(8) is the mathematical expression of the constraints between powered supports and the coal plough. It expresses the relation between action of the supports, the displacement and the moving direction of the coal plough. Support Ki, whose distance to the center of the plough Ki never changes, performs 3 different actions fi separately with various displacements x (or K) of the plough while mining coal.2.2 Constraints between powered supports and scraper conveyor Every pusher cylinder of a support is connected to a section of the ledge of the conveyor, and the pusher jack makes a move. The conveyor is required to bend according to a certain curvature in order to decrease abrasion at the point of flexure while moving. The conveyor is ensured to be flexible in order to decrease traction resistance after half of a stroke.2.3 Automatic control model of powered supports Actually, the Eqs.(7) and (8) are automatic control models of the support location of the plough, which takes the displacement of the plough (x or K) as a variable. The displacement K calculated by the support number (the support number K corresponds to the center of plough pull) changes while the plough is mining coal back and forth. Taking the support K which corresponds with the the center of the plough pull as a benchmark, a set of supports whose locations do not alter relative to support K perform their corresponding actions according to the constraints. By putting i and y into Eq.(8), the automatic control model can be described:When the plough moves to the right, the support KK1 moves 1/p of a stroke; the support KK2 moves 2/p of a stroke; the support Kperforms lower-advance-set operation (At this point, the supports have accomplished half of a stroke).When the plough moves to the left, the support K+K1 moves 1/p of a stroke; the support K+K2 moves 2/p of a stroke; the support K+ performs a lower-advance-set operation (At this point, the supports have accomplished half of a stroke).K is the support number worked by the key-press operation; K1 is the distance calculated by support number between performing support and support K59 .3 System principle structure As shown in Fig. 3, every support is controlled by a subordinate controller and forms an electric hydraulic control subordinate system. COM ports of the primary controller and all subordinate controllers are connected to a communication bus, which constitutes the microcomputer distribution system of powered supports at a fully mechanical coal face5. Advanced response speed of the system: communication between principal controller and subordinate controllers, or among subordinate controllers is direct because the COM ports of the primary controller and any subordinate controllers are connected to a Single Bus and hence the response speed of control among subordinate controllers is advanced.Advanced reliability of the system: in a Single communication Bus system, the normal work of the entire system will not be affected if the primary or a subordinate controller has trouble. Only the broken-down controller, either primary or subordinate, is affected and this incidence is remote. The Single communication Bus system is fairly reliable.Maintenance of the system: after switching off electricity to the primary or subordinate controller, maintenance, can be performed, the hydraulics of the subordinate system can be maintained and components can be replaced. This maintenance does not affect the normal work of the system and is convenient for the system.4 Function of subordinate and primary controllers and system communication Every support is equipped with a subordinate controller which is at the heart of the electric hydraulic control system of powered supports. The subordinate controller monitors data about its own powered support, such as running tension, support action and so on, translates and edits these data and sends out control commands to the support3COM ports of the primary and all subordinate controllers at the mining face are connected to a communication bus, which can realize comprehensive management and establishes system control parameters. The system has adopted a Single Bus, which links the separate subordinate controllers to a network. The subordinate controller monitors and controls the movements of its own support and sends out and receives control signals from the Single Bus to realize controls among subordinate controllers. The primary controller at a mining face initializes the system and sets up parameters and collects signals from the Single Bus to realize centralized inspection and a display of the state of the system.5 Conclusions In this study, we have proposed a mathematical expression of the running constraints between powered supports and a coal plough. We established an automatic control model of powered support and introduced the essential principle of an electric hydraulic control system as well as the function of a primary controller and subordinate controllers. Ten sets of subordinate controllers were constructed in our laboratorium and our experiment shows that the control model agrees with practical considerations.Acknowledgements Our deepest gratitude goes first and foremost to the Education Bureau, which gives us the chance to do the research. Second, we wish to express our appreciation to many people who have greatly contributed to or helped with the development of this article in their special ways. We are especially grateful to a friend named Tom, who has given us much help in the revision of the article. Our gratefulness also goes to those friends who have given us much inspiration and many constructive suggestions.
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