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Procedia Engineering 206 (2017) 449-456
Procedia
Engineering
www.elsevier.com/loeate/proeedia
International Conference on Industrial Engineering, ICIE 2017
Dynamic; if Price;;, Algorithm, and System if Uninterrupted Action LigdingMachine Feeding
G.S. Khazanovich, A.V. Otrokov*, V.G. Chernyh
Shakhty Institute (branch) of Platov South-Russian State Polytechnic University (NPI), 1, Lenin Square, Shakhty 346500, Russia
Abstract
Based on studying the peculiarities of dynamics of working processes of mining loading machines of uninterrupted action the article snbstantiates the principal and a corresponding method of automated control of the feed to the pile providing for the maximum ponsible productivity for the net loaping time with a consideration cf power and energ etic recpurs es of the machine and the stochastic nature of the proc ehs. The onalysis of the long -torm experien^ in solving the problcm provee the ^hi'iciency of using interrupted fned during the hard particle material loading. Realization of the worked out proposal with using modernmeans os microecopy acceesories is fulfilled by thc adequate using mathematical models of changing un the dynamics of the pile state at ohe loading organ influencing it, forming the produetivity, mhe loads in the drive of the work organ and the; process of running dieplacemsnt oa the machine. An algorithm, a program of optimum c onerol, and the implementaeion schedule are developeg dased on the example of s widely useg loading machine.
© 20ro The Authops. Pudiished by Elsevier Ltd.
Peer-review Andhr responsibilityof ths scie^ilic committee of the Internativnal Coherence on Industrial Engineering
Keywords: loading machine of uninterrupted action; the machine maximum productivity; automatic control of feeding to the pile; mathematical model; dinamic loads; the scheme of microprocessor-based system of optimal control.
1. Introduction
In thee process of driving underground mining heading loading of the broken mining mnss is one of the main parts of the technological cycle. Moreover, it is the process of loading and transportation of mining mass that often define the productivity of the whole complex of mining cutting works.
* Corresponding author. Tel.: +7-918-5t9-t3t7; fax: +7-863-622-3088. E-mail address: iav711@gmail.cim
1877-7058 © 2017 The Authors. Published by Elsevier Ltd.
Peer-review under responsibility of the scientific committee of the International Conference on Industrial Engineering. 10.1016/j.proeng.2017.10.500
In mining industry all over the world loading machines of various types using both as separate machines and as loading modules in the composition of roadheading machines are used. All loading organs can be divided into two types: periodical (bucket) and uninterrupted (gathering-arms and gathering-stars) action. Since 1916 when Joseph Joy got his first patent for the machine with gathering-arms, its construction has not been changed greatly, and loading organs using the idea of an apron (feeder) with pair gathering-arms organs moving on various trajectories [1,2] are widely used in underground loading machines and roadheaders all over the world.
Loading machines of uninterrupted action, in spite of their almost centenary industrial producing are hand-operated which can be explained with the complicacy of the process of interaction of the loading organ with the mining mass pile. On the other hand, it is the complicated stochastic character of forming the loads on the mechanism drive of gathering-arm that makes impossible the full using the machine resources even at the operator's great experience. Hence, the problem of creating an automatical device which should increase the reliability and efficiency of the machine in the whole and decrease of the labour intensity of the loading process for the operator is quite relevant.
2. History of working out the system of feeding control
The peculiarity of the technological process of mining mass loading by the machines of uninterrupted action is periodical feeding of the loading organ or the whole machine to the mining mass pile. It takes place because of the fact that the working elements of the loading organ make the choice of the material from the working zone formed on the apron (feeder) making it naked, which, in its turn, leads to the decrease of the gathered material portion and lowering the loading productivity. For compensation of the loaded material the feeding of the machine to the pile is realized, as a result of it the apron intrudes into the material and the volume of the working zone of loading elements increases. The increase of the feed value causes to the increase of productivity of the loading organ, loads to the drive of the executive elements and the power consumed, and the apron intrusion after some maximum value leads to great overloading of the drive and through some material off the apron. In this connection at considering the control system by the process of loading the speech is, in the first turn, about the constructing the automatic feed of the loading organ and of the machine as a whole to the mining mass pile.
Group of scientists of the Novocherkassk polytechnic institute (now Platov South-Russian state polytechnic university (NPI)) [3,4], the Kommunarsk mining-metallurgical institute (the town of Altchevsk, the USSR, the Republic of Ukrain) [5], the Institute of mining technical mechanics AS of the USSR (the city of Dnepropetrovsk) [6], as well as of the Kopeisk and Yasnogorsk plants producing the machines of such types went in for working out the automatical control by the loading machines of the type of PNB during the latest 50 years.
Among the realized in experimental samples machines: there were the machines with regulated direct current drive [5], with differentiated hydrodrive [3], asynchronous drive with generator and impulse regulators [5,7]. The machine of 1PNB-2D type with generator regulator of drive produced by the Kopeisk machine building plant successfully went through the industrial test [5,7], the other samples were tested in stand conditions.
As the movement of loading elements is uninterrupted but the feed of the loading organ is realized periodically, two conception of controlling are appeared: 1) the velocity of automated feed should change smoothly in the function of loading in the drive of the gathering part [3]; 2) interrupted of the machine, the beginning and ending of the cycle of which depend on the level of load in the drive [4].
The conception of uninterrupted regulated feed of the machines of uninterrupted action was based on the affirmation that after gathering the next portion of the material with the gathering-arms the pile evenly crumble as though "retreating" from the immobile standing machine, and it is necessary to feed the machine uninterruptedly compensating the pile retreat. But it happens only on small particle sizes of material pile of a small height. Investigation of loading of large particle size of material [7] showed that on such a pile periodical hanging and breaking down the material take place, and the volume in the active zone of loading elements and productivity of the whole organ change according to the complicates dependences. If the broken volume in the active zone is in 6-7 times more than the volume of a single gather, then the productivity of the loading organ in the area is stabilized and is saved practically maximum during 3-4 gatherings [7]. Such character of the working process makes the discrete control of feed more effective, i.e. the cycle of feed should include 2-4 gatherings at the unchangeable position of the apron relatively to the pile.
Working out the system of control is based both on the materials of the previous investigations [6,8] including the investigation of the loading organs with gathering-stars having the similar physical regularities [9,10], and on the result of computer and physical modeling carried out in the frames of working out mechatronics system of automatical control [1-4,11,12]. Interaction of the system of control and loading machine is reflected in the works [13-15], the influence of stochastic processes during the loading of large particle material - in the works [16,17].
3. Dynamic models of interaction of the machine of PNB type with the pile
The purpose of creating the mechatronics system of automatic control of feed is to reach maximum possible value of average productivity of the loading machine at loading out the pile volume between two turn cycles of maneuvering considering the maximum power, energy abilities of the machine, keeping the demands of reliability and safety with consideration of the following restrictions:
• equivalent power of the drives of gathering and running parts should not exceed the corresponding values of durable power;
• maximum load of the drive and transmission of the grasping part should not exceed the permissible values;
• frequency of turning on the mechanism of feed should not exceed the maximum permissible values;
• power effort of the permissible limits with consideration of the factors of clutching caterpillar with the ground and the power of the running drive.
The final efficiency of the discrete control of delivering the loading machines of non-interrupted action defined with the possibility of reaching maximum productivity at the given level of power and energetic resources depends on the realization of regularities of the two dynamical processes:
а) forming the loads at the material gathering on the shafts of the leading links in the function of their placement at the random change of geometrical outlines of the pile;
б) changing the depth of intrusion the loading organ into the mass of the pile under the action of power efforts of the running mechanism.
The last ones are defined with the dynamics of the process of transmitting the machine at the changing of the command of the machine movement to the pile.
Various constructive-kinematic schemes of the running parts are used in the produced machines of PNB type:
• on the drive type: electrical and hydraulic;
• on the type of connection of the engine and the work organ of the running mechanism (as a rule, of leading sprocket of caterpillar chains) with rigid connection and with the turning on friction clutch coupling.
In the machines of the middle class of the 2PNB-2 type the variant of the electric driver with friction clutch coupling is used, the direct executive element of the turning on device is a hydraulic cylinder.
Let us consider the process of speeding up and transmitting the machines of the given class to the pile. From the positions of description of the dynamic process the loading machine may be represented in the form of three connected links (fig. 1):
• the leading link 1 - an electric driver with the redactor group transmitting rotation to the leading disks of the friction clutch coupling 2;
• the driven link 3 - the redactor group from the driven disks frictions till the caterpillar spiders and the body of the machine;
• turning on device 4 providing the compression of the friction clutch coupling disks 2.
Feeder (head!
Loader
Fig. 1. Equivalent scheme of the drive of the loading machine.
The process of speeding up and transmitting the machine takes place in phases (fig. 1):
1. from pressure supply to the hydraulic cylinder 4 till the beginning of the frictions 2 compression (clearance adjustment);
2. from the beginning of frictions 2 compression tills the beginning of the machine body movement (speeding up in the turning on period);
3. speeding up the machine till the stable speed and to the movement with the simultaneous feed of the apron 6 to the pile.
Beginning conditions: time t=0; the depth of the apron intrusion S(0)=S0; the velocity of feed the machine u(0)=0.
The equation of the mass center movement brought to the advance translation of the machine:
m-Kj f - Fmf - (1)
where m - the machine mass; Fmf - moving axis force, N;
Frf - sum of the resistance forces of machine movement, H;
KJ - coefficient considering brought to the direction of movement moment of inertia of rotating mass. Moving axis forts is defined by the torque transmitted from the driven part of the friction clutch couplings. On the stage 2 after finishing the choice of gaps the moving power may be represented in the form of the relation:
Fmf , N (2)
r pvm zv
where Mm - the moment developed by the driven part of the frictions in the process of compressing, Nm; ivm - transferring relation from the driven frictions to the sprocket of the caterpillars; rpvm - the efficiency of the led part of transmission;
Rv - radius of the beginning circle of the leading sprocket of the caterpillar mechanism.
The value of Mm is defined by the function of forming the effort of disks compression by the hydraulic cylinders. In general case this dependence may be represented by the linear relation, then
Fmf . t (3)
r pvm zv
where Km - coefficient of proportionality between the moment Mm and the current time t, N.m/s. The constant value having been indicated, N/s:
Km '. R (4)
r pvm zv
the moving forces will be written in the form of
Fmf =amft (5)
The resistance forces of machine movement, N:
= Wmp (S) + Wdf
where Wimp (S) - the resistance force of the apron intruding into the pile of material:
Wimp (S) = Kmp ■ Sn
Wf - the resistance force of the machine movement:
Wdf = m ■ g (a>,cosP + sinp)
where m' - coefficient of resistance of the tracks on the ground; P - the angle of inclination of the mining heading ground. Then the equation (1) will have the view
m ^ Kj ltT + K'mP ' Sn + m ^ g ■( ^ C0S^ + SinP) = amf '1
The solution of the equation (9) gives the dependence S(t) till the full completion of the process of turning on the frictions. After that the second stage of the machine moving begins in which the moving power of the running drive is used. For this stage the equation of dynamics will have the form:
• kj • dts=Mf ~kp (s )+wif )
The running drive moment may be represented by the given mechanical characteristic
Mf = A -B ■u
Then the equation (10) will have the form:
m ■ Kj ■ dS = A -B ■ ddS- Kmp ■ Sn - m ■ g ■(' ■ cosfi + sinP)
For solution the equation (9) it is necessary to give the function of changing the twisting moment on the shaft of friction clutch coupling which in the first approach has the form represented in fig. 2.
M, N -m
o tj t, s
Fig. 2. The function of torque change on the shaft of the friction clutch.
4. Algorithm of controlling
As a result of the experimental data analysis and mathematical models the following restrictions of the control algorithm are formulated:
• the machine is moved only forward to the pile;
• making the decision of turning on the feed is realized after finishing the next cycle of gathering the material with
the gathering-arms;
• finishing the machine feed is made according to the condition of forming on the apron maximum-permitted in
charge in the drive of the gathering-arms the material volume.
Mathematical model of controlling is the assembly of mathematical relations and the algorithm if actions of the microcontroller with the help of which after finishing each full revolve of the leading disks the forming of the controlling signal "turning on/off of solenoid-operated hydraulic valve" with the purpose of reaching maximum value of the average productivity of the loading organ qcp.
Analytical objective function may be written in the form [16]:
q T1+T2
qcp = T+-■ J x(t)dt ^ max (13)
where q0 - normative productivity in the given conditions at the depth of intruding the apron nose into the pile realizing the maximum area of the material gathering;
T - time of the machine feed to the mining mass pile;
T2 - time of taking out the mining mass at the immobile apron;
, . q (t)
X(t) - coefficient of productivity the relation of the current productivity q to the normative value; x (t) = -LJ-.
The idea of regulating consists in the fact that at decreasing the load to the executive elements drive, due to decreasing the material active volume till the given minimum (lower) level, it is necessary to turn on the delivery of the loading machine to the pile till the load increasing to the drive till the definite maximum (higher) level, after that it is necessary to stop the delivery and take out the material during at minimum two cycles of the material gathering.
The elements of controlling algorithm giving minimum and maximum levels of load are called setpoint device. The value of the maximum levels of load depends on the character of dropping momentary productivity at increasing the gathering number which, in its turn, depends mainly on the loading organ construction, the pile height and the material granulometric composition. The maximum level is defined in dependence on the value of the permitted short-time load of the drive.
If in the previous [5,7] variants of hardware version of the load regulator constant levels set by the operator before the material loading were used, then in the proposed device the levels are changed automatically on the base of regularly carried out calculating experiment. Modeling is carried out according to mathematical models of the loading processes with consideration of the stochastic character of the loads formation because of the changing of the pile granulometric composition with consideration of the material choosing out [9] which is characteristic for the large particle material. Besides, for the loading machines with executive elements making the complicated movement, for example, with gathering-arms, the load on them depends on their situation on the trajectory. For gathering-arm mathematical expectation and correlational function of the resistance moment on the gathering-arms from the turning angle of the leading disk consists of four sections: the gathering-arm intruding into the pile, gathering of the material portion, pushing the material portion to the conveyer and free movement (return to the initial position). The correlation function also depends on the position of the intruded organ relatively to the pill -the depth of the intrusion and the material volume in the active zone [8].
Analysis of the main indices - momentary productivity, load of the executive elements drive, temperature of the electric drives, the frequency of the mechanism of delivering turn on - is carried out according to the momentary values, the values of mathematical expectations, spectral density, availability of throwing out behind the upper level. For carrying out the leading solution the matrix of conditions consisting of 16 possible variants of the system state is
composed. The microprocessor-based control system changes the level of tuning the setpoint device in the next cycle of gathering for each of variants [8].
5. The system of feed control
The system of feed control represents hardware and software system, and it means that for various constructions of the loading machine of uninterrupted action realization of the given control system will depend on the machine construction.
The worked out system of automatic feed control supposes the availability in the loading machine electric drives of the loading elements and transfer conveyer. Transmitting the torque to the running part of the loading machine is realized via the friction - hydraulic mechanism of turning on/off the feed with the solenoid-operated hydraulic valve which is directed to influence the control system.
The device of automatical feed control (fig. 3) of the loading machine consists of the executive organ 2 driven by the electric drives Ml and M2, the momentary value of the summary current which is measured by the sensor D2; the angle of turning of the leading disks of the gathering-arms is recording by the sensor Dl. Mining mass 1 comes to the transfer conveyer 3 driven by the electric drive M3, the momentary value of the current which is recording by the sensor D3. The signals from sensors D1-D3 come to the microcontroller 8. The electric drive M4 through the gearbox 6 impels the running part and hydraulic pump 5. The machine feed to the pile is realized by turning on the block "hydraulic cylinder - friction clutch coupling" 7, the hydraulic liquid which flows through solenoid-operated hydraulic valve 9.
Fig. 3. The automatic control system feeding the machine with gathering-arms.
The switch of the operating mode 11 having three positions - turned on, manual control, automatic control, permits to choose the operating mode of the system and realized the transmitting control signals either from microcontroller 8 or from the console assembly of manual operating 12.
The system is provided with the display 10 which permits to show the information about the current state of the automatic control system and of the machine as a whole and the port "P" which is used for switching the outer devices (for collecting the data about the work of the device, tuning and removal defects, program updating).
6. Short conclusions
1. The main disadvantage of the loading machines of uninterrupted action widely used at driving mining heading by drilling-blasting method is handle-control by the machine feed to the pile, which is the reason of decreasing its productivity and the reliability indices.
2. Analysis of working processes of forming productivity shows the reasonability using of uninterrupted feeding with controlled levels of tuning the setpoint devices.
3. The objective function of automatic control of feed which provides reaching the maximum value of system average productivity, subject to power and energetic restrictions with consideration of stochastic character of the processes, is proved.
4. On the base of the worked out principals and methods of controlling, mathematical models of forming in the dynamics of volumes the mining mass single gather, load in the drives and running transfers algorithms the program of mechatronic system of feed control and schematic design on the example of the serial produced sample of the loading machine are proposed.
5. On a result of the computer modeling the following indices showing the efficiency of automatic control are received: the productivity increase - 5-15 %; the stock in frequency of turning on the mechanism of delivery - 510 %; the reserve in the drive heating - 10-20 %.
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