Model test of helical angle effect on coal loading performance of shear drum

Intemational Joumal of Mining Science and Technology 22(2012)165-168到Contemts lists avallable at SciVerse Science Direct$30 International Journal of Mining Science and Technology F!AELSEVIERjournalhomepagewww.elsevier.com/locato/iimstModel test of helical angle effect on coal loading performance of shear drumdong Gao*, Changlong Du, Songyong Liu, Lin FuSchool of Mechanical G Electrical Engineering China University of Mining 8 Technology, Xuzhou 221008, CinaARTICLE INFOA BSTRACTing the similarity theory, we carried out a dimensional analysis of the correlation parameters which inftence coal loading performance of shear drum. On the basis of simiLarity criterion, proportionaAvailable online 21 March 2012the model and the prototype was taken on the condition of taking 1 /3 as the sim-arity coefficient. Besides taking 1600 mm drum as thepe, four helical angle models of shearedrums(15.18.21, 24 ] were developed Simultaneously, based on an established cutting test-bed, coalloading performance tests for the four drums were carned out at the same drum rotational and haulagespeeds. After analyzing the data of coai- loading performance and torque. we concluded that: bothmolarity theorycoal loading performance and torque vary along the track of the parabola with the opening side facingCoal loading performanddownwards;the best coal loading performance arises when the helical angle is at 19.3.. while the biggesttorque arises at 22. 1: and the coal loading performance had nonlinear relationship with the torque2012 Published by Elsevier B V, on behalf of China University of Mining Technology1 Introduction2. Determination of similarity ratiosAs a key component of the shear. the drum is mainly used forIn order to get the similarity ratiosmodel and proto-coal cutting and loading, whose performances are the key factors type, it is necessary to carry out dimensalysis of the relatedthat affect the drum performance[1] Scholars have mainly focused parameters first. According to the Retthe mathematicalon the research of the coal cutting performance, and ignored the expression of the coal loading capacity(Q-)is shown in Eq(1].research of coal loading performance [2-13 Al the present, somescholars have changed the structure of drum so as to improve theDal loading performance of the drums, while other scholars haQ=(D-D)(zD, tancos(iu+p)COs opstudied several factors which influence the coal loading performance of drums through theoretical analysis, simulations andexperiments 114-18 It is undeniable that they have got some where D, is the blade outer diameter, mm; D the blade inner diam-achievements. However, few scholars have studied the factors such eter, mm zin the inner helical diameter rad: zout the outer helicalas helical angle and coal humidity which seriously influence the diameter, rad: z the blade number: b the blade thickness, mm; ncoal loading performance of drums. Therefore, it is necessary to the rotational speed, r/min; p the friction angle between coal anddo further experimental and theoretical studies. For coal industry blade, rad: Y, the utilization coefficient of drums unloadingin particular, underground systematic experiments involves much sectionlabor and significant resources, while the real testing machines onApart from the parameters mentioned above, rothe ground occupy large areas, require huge funds and long time (n)and cutting depth(E)of drums also influences the coal loadingwhich will cost vast amounts of human resources and funds. The performance. The coal loading performance of drums would havereal testing machines which are on the ground will also lead to particular relationships with the dynamic characteristics oflarge venues occupied, huge fund devotions and long testing per- granular materials because the fractured coal mass is a particulateds which cannot be bome by ordinstitutions. For these rea- matter. Therefore, several key factors, such as coal granularity (G),sons, we carried out a model test to study the coal loading coal density(P) compressive strength(oB)and coal humidity (n.performance of shear drum and developed a test-bed on basis of are introduced into the research model test theory. Table 1 showssimilarity theory.the dimmension of correlation parameters.responding author. Tel: +86 15162120553中国煤化工 nail address: gaokuidongecumteducn(G. KuidCNMHGlarity theor2095-2686/S- see front matter e 2012 Published by Elsevier B.V. on behalf of China University of Mining&Tdoi:10.1016jmst2011G. Kuidong et al/ International Joumal of Mining Science and Technology 22(2012)165-168Table 3Dimension of the correlation parameterSimilarity coefficients of the correlation parameters.al diameterycal diameter (rad)er(rad)Mdiameter(rad)Cutting depCutting depth(mm)oal loading capacity(m/min)MLOTFnction angle(rad)Coal density (kg/m")Coal granularity(mm)G27Coal humidiMLT 2opressive strength(Pa)Gravity acceleration(misof similarity criterion is the total number of parameters(m)minusdimensional matrix rank(r)[ 19. Therefore, we may conclude that adopted as the geometric similarity coefficient. Then, the similaritythe number of similarity criterion is 13 from Tabies 1 and 2, Be- coefficients of the correlation parameters of the model drums arecause the dimensionless physical quantity can be treated as an shown in Table 3.independent T-term, the number of similarity criteria to solve is8 We used an analytical exponential method in the dimensionand computed the T-terms of the correlation parameters. These 3. Model test researchare shown in Eq(2)According to the ref [20 data range of the helical angle is 8-器n=器,30. while in practical production of shear drum with diameter of1600 mm. the data range of the helical angle is 16-24. In order兀==,=(2) to research on the effect of drum structural parameters on coalI,=ro, 7s=gr, ng=nloading performance, four models of shear drums were developedy analyzing the similitude ratios of relative parameters in Fig. 110=awt,1=2,x12=q,丌t3=with a 1600 mm drum as the prototype and their respective helicalSimilarity coefficients are the ratios of the model's parameters the drum. The main structural parameters are shown as followsory, the T-terms are all invaariant Baased on this, the relations of thedrum diameter is 530 mm: blade outer diameter is 420 mm: bladesimilarity coefficients can be shown as in Eq- (3).inner diameter is 200 mm: blade number is 2: blade thickness is25 mm; cutting depth is 330 mm.1,In practical production, the rotational speed of a 1600 mmdrum is 20-100 r/min, while the drag speed is 0-8 m/min Accord-容=1ing to Table 3, the rotational speed of the model drum is 34-174 r/(3) min, while the drag speed is 0-4. 6 m min. The cutting test-bedq=1,￥=1(Fig. 2)which has been established can satisfy the requirementsof the tests (rotational speed: 20-100 r/min, drag speed: 0-10 m/Can= Ca =c2= Co=Cr=1When the shear drum is at work, some coal is pushed to theTaking the length(L)as the fundamental quantity and presume back of the drum and become float coal. some fell to the area be.that C-1/Ks as the geometric similarity coefficient, thenween chute and coal wall, while the rest is casted to the scraperD, =CDs=CB=CE=CG=CL=1/k,conveyor and taken away, In order to simulate the real situation.Since the same material was used in the tests, so the density shown in Fig 3. Areas"W and"A"stands for cutting depth andoefficient Cp-1[7]. Simultaneously. the similarity ratios of the the area between chute and coal wall, respectively. the coal inother parameters are obtained by presuming Cx-1these two areas is called unloading coal, and the rest on the grouris called loading coal. Coal loading performance can be indicated bythe ratio of coal loading capacity to total mass. Model tests wereGenerally, the larger the similarity coefticient we take in the carried out on the four types of drum under the same conditionsodel test the smaller the error we will get. In order to make test (rotational speed 100 r/min while drag speed 1 m/min )results closer to the real situation in the budget range, 1/3 was Finally, coal loading performance and torque curves were obtainedDimensional matrix of the comelation parameters.YH地B010G, Kuidong et al /Intemational Joumal of Mining Science and Technology 22(2012)165-168Fig. 1. Drum physical diagram for test.5. Shaft joint 1: 6. Reducer I' 7 Shaft joint 2: 8. Torque transducer; 9. Shaft joint 3 10. Shaft block: 11. Supportwall container: 13. Test drum; 14. Test coal wall; 15. Pinion and rack; 16. Vertical translation guide way: 17.Reducer 2: 18 Shaft joint 4: 19. Hydraulic motorFig 2. Cutting test-bed4. Results and discussionArtificial coalwallFig. 4 indicates that the torque curve of the shear druIated in a period less than 1 s. This resulted from the oveFloat coaregion between wrap angles of the blades which madeto overlap longitudinally. During the rotational cutting. the twoModel drumpicks of this region cut the coal simultaneously and the cuttingthickness change from thin to thick, and then become thick. thiss how the fluctuations shown in Fig 4 were produced. The theo-retical fluctuating period is 0.83 s, which can be derived from thesame with period of the curve. Fig 4 shows that the loading perfor3mance of shear drum attains the best value when the helical angleis 21 and the worst value when the helical angle is 24. Fig. 5 indiER Landingcates the torque is attains the best and the worst values when thehelical angles are 21 and 15, respectively. the changing laws ofthe loading performance torque and curve-fitting of the data areshown in Fig. 5. The torque's fitting curve equation changing alongthe helical angle is shown as follows:Tn=-3655x2+160714x-902353where the correlated coefficient is 0.737The fitting-curve equation of loading performance changingHn=-0373x2+14476x-76548where the correlated coefficient is 0.859Fig. 3. Simulation of coal loadingcurves. it can be seen that the loading per中国煤化工 ic trend along with the-ind the rising rate is inas Table 4 and Fig. 4 are showing. Through the analysis of the the ralC N MH Gical production).Whiletorque curves, the statistics of torques were obtained as shown the loadingLlldiiges sugnuy and shows symetricn Table 5forms on the rising and following in 16-24 range. Extreme valuesG Kuidong er al/ Intemarional Joumal of Mining Science and Technology 22(2012)165-168Table 4indicating they have nonlinear relationship. therefore, we shouldCoal loading performance for different helical angle drumstake several factors into consideration when designing the helicalangle of drums.mass (kg (421.3035 Conclusions33872331.1345605355.54According to the model test of the effects of helical angle on coalloading performance, we may conclude as follows(1)Both the coal-loading performance and torque varied alonghe track of parabola with opening side facing downwards;the best coal loading performance was obtained at the heli-soEA AX PH N/A4cal angle of 19.3, while the biggest torque was obtained atelical angle of 22. 1 the torque, which has a nonlinear rela-tionship with the coal loading performance, does notincrease with increasing of the coal loading performance.(2)The test results can represent real situation because thec2model drums are produced on basis of the similarity theory.angle.8°In order to attain the best coal loading performance, we sug-ngle21°gest the helical angle of the drum whose diameter isange24°600 mm should be193°0AcknowledgmentsTime(s)Thanks to the financial support for this research provided by theF 4. Torque loads of different drums.National Natural Science Foundation of China(No5 1005232)anthe postdoctoral Science Foundation of China(No. 20100481176].Table 5ReferencesTorque of different helical angles drums.I11 Fu wx, Lu Z Analysis on the structure and coal loading performance of shearjum(N m)Im(N m) M12) Tao CD. Chen C On optimum design of the shearer drum. J Chin Univ Minchnol19966(1):15-23wran V. Effect of rate of sumping on fragmentation8013929College of Engineering and mineral924732761547geometry in multipleeraction. USA: College of Engineering and Mineral Resources at west15l Liu CS. Fractal characteristic study of shearer cutter cutting resistance curves, J1000161 Du CL Liu SY, Cui xx, li T]. Study on pitement of shearer drum basedI7 Lju SY. Du CL Cui xx, Cheng X Mode9: 19(1):74-8e cutting properties of a shearer[8 Goktan RMindex and drag pick cutting efficiency, South Afr InstCoal loading perd191Towards the identification of worn picks on cutterdrums basedchange of heliceate Tee nod 2owe 2 5:22..uSing Amncal Neural Networks. Tunn Undergr[111 uusY, Duca element modelling of rock cutting Comput Methods Mater- Torque correspond to change of helical[12] Liu SY, Du CL Cui X, Song J Modeling Experi1618Science and TechnologyFlg 5. Relation of helical angle to coal loading percentage and torque12uxm2门m址of the loading percentage and the torque occur at 19.3 and 22. 1. [16] Liu Z Zhu HL Ex maich 1987: 4 4-7g performance of she: 06(1):51-6.The 4 torques of the drums caused by pick cutting are similar [1m wang aL Liu Z Study on loading e Huainan Min inst 1 atin of loadingslectiveshears affecting turningbecause they are arranged in order, with the same amount, type, [18)Liinstallation angle and nodal line. the differences lie in the torque中国煤化工Ⅻchcaused by blade coal loading. We can see from Fig. 5 that the trend [19 YCNMHGnd statics. Chengdu Southwestof coal loading performance and torque are basically the samewhile their variation patterns do not correspond to each other [o\ mining a lechnology Press:2003.42-44