锥式破碎机的发展@中英文翻译@外文翻译

Wear xxx (2006) xxxxxxAbstractpreewerebetweenpressure,withK1.industrypartsmantleinthrusthydraulicforinisrock(seecledistancesetting,thetaintocmemvs.chalmers.se0043-1648/$doi:10.1016/j.wearDevelopment of wear model for cone crushersM. Lindqvist, C.M. EvertssonDepartment of Applied Mechanics, Chalmers University of Technology, SE 412 96 Goteborg, SwedenReceived 30 March 2005; received in revised form 2 November 2005; accepted 12 December 2005Cone crushers are used in the aggregates and mining industries to crush rock material. A model to predict the worn geometry of cone crushers wasviously developed. In that model there was some disagreements between predicted and measured geometry and several effects were suggested toxplain the discrepancy in the model. In this study the effect of shear forces along the crushing surfaces was implemented in the model. Simulationscompared to measurements on two different crushing chambers. The results show a significant improvement with respect to the discrepancymeasured and simulated geometry. Measurements were made on a coarse crushing chamber where the operating parameters hydrosetpower draw and capacity were tracked during the lifetime of the set of liners. The simulated operating parameters show some agreementmeasured data, but the crusher was not run under ideal conditions at all times.2005 Elsevier B.V. All rights reserved.eywords: Comminution; Crushing; Modelling; Abrasive wear; Cone crusherIntroductionCone crushers are widely used in the mining and aggregatesto crush blasted rock material. The two main crushingdeveloped a flow model, a size reduction model and a pressureresponse model.The geometry of the crushing chamber is crucial for the per-formance. Due to wear the geometry of the liners will change,are the mantle and the concave. The main shaft of theis suspended on a spherical radial bearing at the top andan eccentric at the bottom. A hydraulic cylinder supports thebearing that carries the thrust force of the main shaft. Thesystem can raise the main shaft in order to compensatethe wear of the mantle and concave. The hydraulic pressurethe cylinder that supports the thrust force from the main shaftcalled the hydroset pressure. As the eccentric is turned thematerial will be squeezed and crushed between the linersFigs. 14).Along its path through the crushing chamber, a rock parti-will be subjected to several crushing events. The shortestacross the crushing chamber is called the closed sideCSS, and is an important variable for the performance ofcrusher. The control system is calibrated regularly to main-a constant CSS. Previous research 1,2 has made it possiblemodel the behaviour of a given cone crusher. Evertsson 1Corresponding author. Tel.: +46 31 772 13 76; fax: +46 31 772 3872.E-mail addresses: mats.lindqvistme.chalmers.se (M. Lindqvist),(C.M. Evertsson).andtimesgeometrypurposeonthereandberItlinerbywtheproposedpressuretorwshoatingslightchamber see front matter 2005 Elsevier B.V. All rights reserved.2005.12.010hence the crusher performance will also change and some-suffer. Therefore it is desirable to simulate the change ofand performance as the liners wear. A model for thiswas previously developed 3,4. That model was basedthe results of Evertsson 1. In the model for wear predictionwas some discrepancy between the simulated geometrymeasured geometry in the upper part of the crushing cham-3. Several explanations of this discrepancy were suggested.was first assumed that the work hardening behaviour of thematerial might depend on the applied pressure. In a studythe author 5 it was concluded that it was not a variation inork hardening in the chamber that caused the discrepancy inwear model.Among the other explanations for the discrepancy, that wereby Lindqvist and Evertsson 3, the prediction ofon the liners was assumed to be an important fac-. To address this, an improved flow- and pressure modelas presented by Lindqvist and Evertsson 6. That modelwed a significant improvement in prediction of the oper-parameters CSS, power draw and capacity, but only aimprovement of wear prediction for a fine crushing.WEA-97899; No. of Pages 82 M. Lindqvist, C.M. Evertsson /Fig. 1. Cone crusher, schematic image.Fig. 2. Operating principle of cone crusher.Fig. 3. An H8800 hydrocone crusher. This particular model is nearly 5 m high.betweenrockChenjerelationshipwearforleastpresenttheofmodel,one2.2.1.isprewearbetweenwhererock.rial.theofsmall,themainwearlinerwearmotionOnWear xxx (2006) xxxxxxFig. 4. A new set of crusher liners, mantle and concave.Other suggested explanations are non-linear dependencypressure and wear, shear stress at the interface betweenand liner, dependency between particle size and wear rate.and Radziszewski 7 showed that there was a non-linearbetween applied force and wear rate in a slidingexperiment. If Chenjes 7 results were also applicablethe case of non-sliding wear in cone crushers, they would, atin part, explain the discrepancy. The technique used in thestudy, to measure the geometry of the liners, is similar totechnique used by Rosario 8. He has made measurementsliner wear on gyratory crushers.Among the possible explanations of the disagreement in theshear forces in the contact between rock and liner is thethat is addressed in this paper.MethodWear modelThe wear model presented by Archard 9 suggests that wearproportional to sliding distance and applied pressure. In thevious work carried out by the author 10 it was found thatoccurs even if there is no macroscopic sliding motionrock material and liner. This is the case in a cone crusherthere is no macroscopic sliding motion between liner andThe mantle is free to roll against the bed of rock mate-On at least one point, the point of moment equilibrium formantle, there is pure rolling between the mantle and bedmaterial. At other points the relative sliding motion is verysince the concave is designed nearly as an ideal cone withgeneratrix of the mantle intersecting the pivot point of theshaft (see Fig. 5).The wear model presented by Archard 9 suggests that therate is proportional to sliding velocity. If a worn crusheris inspected, no ploughing grooves can be observed. Themechanism is squeezing wear without macroscopic relativebetween the bed of rock particles and the steel surface.a small scale there is of course some relative motion since/Fig.theparticlesthisdependentyieldtheEvcrushingsurethismaterialandandN/mmDelta1wlaronmechanicalofofminedv94abrasisteel.binationwearheretheeralM. Lindqvist, C.M. Evertsson5. Mantles are designed nearly as an ideal cone whose generatrix intersectspivot point of the main shaft.are rearranged as they are crushed, but the direction ofmotion is random. A wear model like Archards 9 that isof sliding velocity would in the case of cone crushers,no wear. Therefore, Lindqvist and Evertsson 3 adaptedwear model used for cone crushers.In the model for wear prediction, described by Lindqvist andertsson 3 it is proposed that the amount of wear in a singleaction is proportional to the maximum average pres-p that occurs during the crushing event (see Eq. (1). Inconstitutive equation W is the wear resistance coefficient, aparameter unique for each combination of rock materialsteel. Wear w is here expressed in mm, pressure in N/mm2,hence the unit for the wear resistance will have the unit3.=pmaxW(1)The “average pressure” expressed in Eq. (1), consists of age number of contact loads of different magnitude actingthe steel surface. The wear that occurs is a function of theproperties of the steel, the number and magnitudethe contact loads, and the shape and mechanical propertiesthe rock particles. The wear resistance coefficient W is deter-by the mechanical properties of the steel and rock, and iserified in experiments or in full-scale measurements.The wear resistance parameter W in Eq. (1) was found to bekN/mm3in a previous study 3. The material was highlyve quartzite in combination with austenitic manganeseIt was shown in that study that the wear model in com-with the crusher model yielded an under-prediction ofin the upper part of the crushing chamber. The objectiveis to present a model that will address this discrepancy.If a particle squeezed between oblique surfaces, as in Fig. 6,shear force increases as the nip angle increases. Among sev-mentioned and partly investigated reasons, a shear force in aFig.(left)contacttacttoindicatesthefullyforcesqueezedticleproductfrictionofNfNFig.surfWear xxx (2006) xxxxxx 36. The nip angle between the liners is larger for a coarse crushing chamberthan for a fine chamber (right).is here assumed to change the stress state around the con-and increase the wear rate. As mentioned, it is not possibleobserve any ploughing grooves on a worn liner surface. Thisthat there is no macroscopic sliding motion betweenrock particles and the steel surface and that friction is notdeveloped.If a particle is squeezed between oblique surfaces, the shearin the contact can be computed. Consider the particlebetween two oblique surfaces in Fig. 7. Since the par-does not slip, the friction is not fully developed.The tangential frictional force Ftcan be decomposed as theof a frictional factor f times the normal force N. Sinceis not fully developed f where is the coefficientfriction. With reference to Fig. 7, equilibrium require that= F cos2(2)= F sin2(3)7. Shear forces are present when a particle is squeezed between obliqueaces.4 /Fig.concafthetoLindqvistsionbed:ofdecoefpressureFig.surfppwhereresponseDelta1wshearhaswearM. Lindqvist, C.M. Evertsson8. Simulated pressure distribution on a mantle used with an H6800 ECve.: fN cos2= N sin2(4)= tan2(5)If the computed factor f exceeds the coefficient of friction,particle will slide.In the crusher model, the pressure is computed accordingthe pressure response model presented by Evertsson and4. The pressure response model relates compres-ratio (i.e. the compressive engineering strain of the particledeformation/original thickness), and variational coefficientthe particle size distribution to crushing pressure. A second-gree polynomial in two variables (compression and variationalficient of size distribution) was fitted to test results. The totalptotis computed using the pressure response model (see8).So the shearstress pshearand normal pressure pnormalat theace is hence computed according to Eqs. (6) and (7).normal=1radicalbig1 + f2ptot(6)shear=fradicalbig1 + f2ptot(7)ptotis the total pressure computed from the pressuremodel. The proposed wear model hence looks as:=1W(pnormal+ Kpshear) (8)Here K is a new model parameter that scales the effect of theforce when there is no slip. Sliding wear in a jaw crusherbeen found to be three to six times faster than squeezing-only, at the same crushing load 10.2.2.suringmethodistheattachedmotormotorsmotoringtheoflocatedThea32250mary3.3.1.andFig.concaWear xxx (2006) xxxxxxFig. 9. Measurement rig.Wear measurementsA measurement rig that was previously developed for mea-the worn geometry of cone crushers was used. Theresembles the one used by Rosario (2004). The crusherstopped and a probe detects the location of the surfaces ofmantle and concave. The device is made of a frame that isto the main shaft of the crusher (see Fig. 9). A stepmoves a carrier by turning a threaded rod. Small steppingsend out probes. The number of pulses sent to the stepcorresponds to a certain position relatively to the measur-frame. When a probe contacts the liner the controller stopsmotor and the number of pulses is registered. The numberpulses is then converted into geometric coordinates.The measurements were carried out at the NCC quarryapproximately 70 km:s east from Goteborg, Sweden.crusher was a secondary SANDVIK H6800 crusher, withcoarse crushing chamber. The material fed to the crusher wasmm granite that had previously been crushed in a pri-jaw crusher.ResultsMeasurementsThe coordinates from the measurements were transformed,the measured geometry was entered into a CAD-tool. Fig. 1010. Measured geometry compared with a 3D-CAD model of mantle andve./Fig.twshoof3.2.model.usingwindependentgeometryanwearshearwearwmaximumoneberwearEhesignificantlycrushingusedofinabrasiM. Lindqvist, C.M. Evertsson11. Simulated geometry of a worn mantle profile at different times, usingo different wear models.ws the measured worn geometry, compared to a cross sectionthe nominal CAD-geometry.Simulation versus measurement of wearThe worn liner profiles were computed using the crusherFig. 11 shows worn mantle profiles at different times,the two different wear models. The left profile shows theorn geometry obtained using the previous wear model that isof shear forces. The right profile shows the wornfrom the new shear-dependent wear model. There isobvious difference between the two models in prediction ofin the upper part of the chamber. The effect of non-slidingforce is scaled so that simulations fit measured data. Themodel parameter K in Eq. (8) was selected so that the wearas correctly predicted at two points on the liner: where thewear occurs, near the bottom of the mantle, and onpoint located near the top of the liner, one-third of the cham-height from the top. K = 50 gives the best agreement. A shearfactor of 50 may seem high, but the shear force factor f in(5) is small, since the angle between the liners is small.Fig. 12 shows the measured and simulated wear on an H6800The wear is computed as the difference between nominalw and worn geometry, measured in the normal direction ofsurface. As can be seen in Fig. 12, the new wear modelimproves the wear prediction in the upper part of thechamber compared to the old model. The flow modelhere was presented by Lindqvist 6.Fig. 13 shows simulated and measured wear on the concavea worn SANDVIK H3000 MF chamber. The measurementFig. 13 was made by Lindqvist and Evertsson 3. Highlyve quartzite was crushed. The simulation in reference 3Fig.ECafterwmodeltheshoandsimulator3.3.parpanelcrushertocrushercrusher250Fig.chamberWear xxx (2006) xxxxxx 512. Simulated and measured amount of wear on the mantle of an H6800liner set. The geometry was measured in the normal direction of the surface385 h of operation.as made with the flow model presented by Evertsson 1. Thatis slightly different from the one used here. Fig. 12 showswear on the mantle of a Sandvik, H6800 crusher, Fig. 13ws the wear on a Sandvik H3000 MF concave. The mantlethe concave have different local coordinate systems in the, hence the difference in y-coordinate.Simulation versus measurement of operatingametersHydroset pressure and power draw were read off the controlof the crusher once every day. When the inlet bin of theis entirely filled with rock material, the crusher is saidbe choke fed, and this is the preferred way to operate a cone. Readings were taken during normal operation of the, i.e. choke fed conditions. The feed was between 32 andmm and came from the primary crusher.13. Simulated and measured wear on a concave of a SANDVIK H3000 MF. Measurements were made by Lindqvist and Evertsson 3.6 /weartionassonwgeometryhydrosetrequireulationspoasandtakinginingeccentricboundarymanufdraadependenttheconstantdranominalherebeltagewillchamberKandduringFigs.byationM. Lindqvist, C.M. EvertssonFig. 14. Correlation between power draw and hydroset pressure.The wear model is indifferent to how time is scaled, and therate is exaggerated in the simulations, to save computa-time. The wear was accelerated by a factor of 4700 times,compared to the wear rate found by Lindqvist and Everts-3. If the wear rate is accelerated too much, the simulatedorn geometry will deteriorate as compared to the measured.Fig. 14 shows the correlation between power draw andpressure. The model for flow and crushing pressurea validation of some model parameters 7. In the sim-made here, the model parameters were selected so thatwer draw and hydroset pressure were predicted as accuratelypossible with respect to average measured data. Power drawhydroset pressure cannot be predicted accurately withoutlosses into account. Losses in a cone crusher arise mainlythe electric motor, the belt drive, the roller bearings support-the driveshaft. Frictional losses occur in the top bearing, thebushings and the spherical thrust bearing who are alllubricated plain bearings. According to the machineacturer, this particular crusher usually has an idle powerw of 3035 kW. The mass of the main shaft corresponds tohydraulic pressure of 0.28 MPa. To adjust for losses, loadand load independent losses were simply added tonominal data to make simulations match measured data. Aload independent loss of 35 kW was added to the powerw and the load dependent loss was computed by dividing thepower draw by the total efficiency. The efficiency usedwas 59%. If the losses are subdivided onto electric motor,drive, driveshaft, bevel gear and eccentric bushing, the aver-efficiency of each of these power-transmitting componentsbe about 90%. The two model parameters for an H3000 MCthat were found by Lindqvist 6 were K1= 0.312 and2= 1.01. For this crusher, which is much larger, K1= 0.3590K2= 1.2387.Readings of power draw and hydroset pressure were takennormal choke fed conditions once every day (see15 and 16). The time of these readings were only specifieddate. The number of hours per day each crusher was in oper-was recorded, and was below 8 h every day. This meansthereingSimulatedtoasrespondsmantledailythatcrushingandthatcrusherfluctuates.predicted.inpoWear xxx (2006) xxxxxxFig. 15. Power draw, simulation and measurement.is an inaccuracy of less than 8 h as for when each read-was made. Simulated time has here been expressed as dates.time corresponds to the time it takes for the modelproduce the same amount of maximum wear on the mantleis measured. In other words, maximum simulated wear cor-directly to simulated time. The maximum wear on thewas 48 mm in the last measure