顎式破碎機畢業(yè)設(shè)計翻譯

1、liner wear in jaw crushersm. lindqvist *, c.m. evertssonabstractwear in rock crushers causes great costs in the mining and aggregates industry. change of the geometry of the crusher liners is a major reason for these costs. being able to predict the geometry of a worn crusher will help designing the

2、 crusher liners for improved performance.a model for prediction of sliding wear was suggested by archard in 1953. tests have been conducted to determine the wear coefficient in archard s model. using a small jaw crusher, the wear of the crusher liners has been studied for different settings of the c

3、rusher. the experiments have been carried out using quartzite, known for being very abrasive. crushing forces have been measured, and the motion of the crusher has been tracked along with the wear on the crusher liners. the test results show that the wear mechanisms are different for the fixed and m

4、oving liner. if there were no relative sliding distance between rock and liner, archard s model would yield no wear. this is not true for rock crushing applications where wear is observed even though there is no macroscopic sliding between the rock material and the liners. for this reason, archard s

5、 model has been modified to account for the wear induced by the local sliding of particles being crushed. the predicted worn geometry is similar to the real crusher.a cone crusher is a machine commonly used in the mining and aggregates industry. in a cone crusher, the geometry of the crushing chambe

6、r is crucial for performance. the objective of this work, where wear was studied in a jaw crusher, is to implement a model to predict the geometry of a worn cone crusher.1. introductionjaw and cone crushers are commonly used in the mining and aggregates industry. today, it is possible to predict the

7、 performance of a cone crusher, provided the geometry, crusher settings and the characteristics of the material fed into the crusher are known (evertsson, 2000). the geometry of the crusher will change because of wear. being able to predict the worn geometry will help optimizing the design of the ne

8、w crusher for improved performance throughout its lifetime.current research and knowledge in the field of wear is very extensive. however, much of this research is conducted from a material science perspective on a micro-scopic level. the objective is often to gain knowledge in material selection si

9、tuations, heat and surface treatment and so forth. in this work, wear on a macroscopic level has been studied, aiming to understand and prevent the damaging effect of the inevitable wear in cone crushers.1.1.rock crushersin a cone crusher, the shaft of the inner mantle is suspended in two bearings,

10、one eccentric at the bottom and one concentric at the top. when the eccentric at the bottom is turned, a vertical cross section of the inner mantle will suer an oscillating motion. the rock particles between the inner and concave will be squeezed, crushed, and fall down. when the material passes thr

11、ough the crusher, it will be subjected to several crushing actions. the properties and performance of the crusher are strongly dependent on the stroke and bed thickness. because of wear, these geometric quantities will change during the life of the liners. in turn, when the geometry of the liners ch

12、anges, the performance of the crusher will change. with very few exceptions, this will be a detrimental effect.in order to design a crushing chamber it is desirable to be able to predict the geometry of the worn chamber. the objective of this study is to develop a model for this purpose. with such a

13、 model, it will be possible to per-form simulations in order to design crusher chambers that are less sensitive to wear.1.2. wear mechanismsthe research and literature on abrasive wear and wear mechanisms is very extensive. a lot of different wear situations have been described, but generally four t

14、ypes of fracture are described as being present in abrasive wear: fatigue, shearing of junctions, microcut-ting and impact (vingsbo, 1979). there are also sec-ondary effects such as frictional heating and corrosion that aect the material/wear mechanism. much of the research is done on a microscopic

15、level. in this work, no further attention will be paid to such topics.a model for predicting material removal due to wear was suggested by archard (1953). in this model, it is assumed that wear is proportional to pressure and sliding distance. hence, in order to use archard s wear model, the local p

16、ressure and motion the crusher need to be known in. one difficulty in determining the wear resistance coefficient in archard s model is the fact that the abrasive particles are crushed during wear. some results have been achieved by (yao and page, 2001; yao et al. (2000), who have studied wear durin

17、g crushing of silica sand. they have studied surface damage on a microscopic level after a single crushing event. to obtain the wear resistance coefficients needed in archard s model, it is necessary to make the measurements after a repeated number of crushing events. their research indicatesparticl

18、es, however, that a testing device for determining the relationship between wear, pressure and motion will need to resemble the process in a real crusher, where rock material is crushed, mixed and crushed again. after a large number of repeated crushing events, the worn geometry will be measured. in

19、 order to predict the worn geometry the components in archard s wear model, the pressure and relative motion must also be known.1.3. test equipmenta few schematic testing devices for determining wear coefficients were suggested by hutchings (1992). for crushing applications, methods such as the pin

20、on disc test have the drawback that the abrasive properties will change during crushing. this has also been proven by yao et al. (2000), who have found that by appropriate control of pressure and shear force, a protective layer of material can be formed near the surface. this means that a testing de

21、vice for determining wear coefficients needs to resemble the conditions in a real crusher, where material is crushed, mixed and crushed again. it is also desirable to measure the crushing forces during crushing, to verify the pressure.2. experimentsrock material is fed into the top of the crusher. t

22、he rotating eccentric shaft and the link give the right liner an oscillating motion that will crush the material. the left, stationary liner has three load cells. two of them are horizontal, to measure normal forces, and one ver-tical to measure the frictional force. the force cells have been design

23、ed to be insensitive to bending and torsion. they only register compressive/tensile forces. the liner material is manganese alloy steel, commonly used for crusher liners, with 1.2% c, 12.5% mn, 0.6% si and 1.5% cr. austenitic manganese steels are common in abrasive wear applications; they are well k

24、nown for their excellent capacity for work hardening. upon plastic deformation the austenite in this material transforms into martensite and becomes harder. there are various explanations for this strain-induced hardening; but the major mechanisms that drive the transformation are twinning and slipp

25、ing of dislocations (el bitar and el banna, 2000).the small jaw crusher was used to study the wear as a function of force (i.e. pressure) and motion. the experiments were carried out using quartzite, since this material is known for being very abrasive. the size distribution of the feed material was

26、 811 mm. the closed side setting (the minimum distance across the crushing chamber) was set to 2, 3 and 5 mm. in compressive crushing, two modes of breakage were identified by evertsson (1998): inter-particle breakage and single particle breakage. the reason for selecting size distribution and crush

27、er setting in this study was to ensure inter-particle breakage. inter-particle breakage occurs when the size of the particles is smaller than the bed height i.e. particles will be crushed against each other; as opposed to single particle breakage when a single particle is crushed between the two ste

28、el liners.the forces were registered and the motion of the crusher was measured by recording a signal indicating the eccentric angle of the main shaft. wear of the liners was measured on a 13 by 8 grid with 10 mm spacing on each liner. the average wear on each level in the downward direction was com

29、puted.3. discussionaccording to podra, 1997, the predicted life can deviate by more than 90% when the linear wear equation is used. this is in agreement with yao et al. (2000), who found a change in wear mechanism as pressure increased during crushing of silica sand. hutchings (1992), made a distinc

30、tion between wear caused by brittle fracture and plastic deformation. based on simple theory, hutchings suggests a linear wear model identical to archard s for plastic deformation wear. for wear caused by brittle fracture, several non-linear models are suggested. in the non-linear methods quoted by

31、hutchings, wear is pro-portional to pressure raised to an exponent of between 1.125 and 1.5. the pressure used in the wear prediction here has been calibrated by measuring the forces that occur during crushing. it has been possible to calculate the average pressure on the crusher liners from the mea

32、sured forces and the geometry and motion of the crusher.the feed material, quartzite of size distribution 811 mm, was selected since it is known for being very abrasive and to ensure inter-particle breakage. the liner material, manganese steel, is well known for its excellent capability of work hard

33、ening. this eect is generally not observed when crushing quartzite, however. it may be necessary to take the eect of work hardening into ac-count when crushing other materials than quartzite. the influence of particle size distribution on wear rate may need to be investigated further.figs. 19 and 20

34、 shows a similarity between simulated and measured geometry. the crushing chamber in the jaw crusher used in these experiments is 120 mm high. the boundary eects (poor confinement of particle bed near top and bottom of crusher) will be less significant in a cone crusher, since the crushing chamber i

35、s much higher compared to the bed thickness and stroke. an-other circumstance that may be beneficial is that the motion of the cone crusher in a vertical cross section is synchronous. in a certain vertical plane, the closing and opening takes place simultaneously everywhere in a cone crusher. this i

36、s not the case for the jaw crusher, which opens at the top while closing take place at the bottom. hence, discrepancies between modelled and measured wear at the top and bottom of the crusher, can be expected to be smaller in a real crusher. the objective of this study was to predict the geometry of

37、 the worn crusher regardless of how long it takes. it is not so important to be able to predict the wear rate. it is more important to predict how the geometry changes in the worn crusher, regardless of time.4. conclusionsthe flow model is not accurate enough to predict pressure in the jaw crusher w

38、ithout additional measurements. the relationship between wear and pressure has proven to be reasonably good (see figs. 5,19,20). the pressure distribution is similar to the wear distribution with the exception of the lower part of the crusher. fig. 21 shows that wear is proportional to time. this is

39、 in agreement with archard s wear equation. this is promising since there are reasons to assume that wear prediction will be more accurate in a cone crusher. the next step will be to implement the wear model for the cone crusher (figs. 22 and 23).翻譯：顎式破碎機襯板磨損分析摘要：在采礦和集料行業(yè)中穿鑿破碎巖石造成很大的成本浪費。破碎機襯板的變形是造成

40、這種現(xiàn)象一個重要的原因。因此，能夠預(yù)防破碎機襯板磨損的設(shè)計將幫助破碎機提高其提高性能。在1953，這種滑動磨損的模型被archard首次提出。隨后進行的實驗，確定了在archard的模型的摩擦系數(shù)。用一個小的顎式破碎機進行試驗，研究破碎機的不同設(shè)置下破碎機襯板的磨損情況。實驗選用石英巖，一種非常粗糙巖石。破碎的力量被記錄，破碎機襯板的磨損情況和破碎的運動也被追蹤。試驗結(jié)果表明，磨損機制對于定顎和動顎是不同的。如果有巖石和襯板之間的距離沒有相對滑移，archard的模型將產(chǎn)生無磨損結(jié)果。這是不合理的巖石破碎磨損觀察，因為即使是沒有巖石材料和襯墊之間mac-roscopic的滑動效應(yīng)，磨損也會產(chǎn)生

41、。出于這個原因，archard的模型已經(jīng)修正為由粉碎顆粒的局部滑動引起的磨損。這種預(yù)測磨損形狀更接近于現(xiàn)實中的破碎機的情況。圓錐式破碎機是在采礦和集料行業(yè)常用的機器。對于圓錐破碎機，破碎腔的形狀是影響性能的關(guān)鍵。研究顎式破碎機的磨損，目的是創(chuàng)建一個模型來預(yù)測磨損的圓錐破碎機的幾何形狀。1。介紹顎式和圓錐破碎機常用于挖掘和集料行業(yè)。如今，在提供幾何學(xué)知識、破碎機設(shè)置和投入破碎機的物料一致的情況下，預(yù)測圓錐破碎機的性能是可能（evertsson，2000年）。破碎機的幾何形狀會改變。能夠預(yù)測磨損的幾何形狀，將有助于優(yōu)化設(shè)計新的破碎機，使其在整個使用壽命中的表現(xiàn)有所改善。目前對磨損的研究在實踐和理論

42、領(lǐng)域是非常廣泛的。然而，這項研究大都從微觀層面進行，從材料學(xué)的角度來看。通常其目的是獲取材料選擇情況，熱處理和表面處理等知識。在這項工作中，宏觀層面上的磨損已被研究，旨在了解和預(yù)防圓錐破碎機的必然磨損所造成的破壞性影響。1.1。巖石破碎機在圓錐破碎機，內(nèi)部地幔的軸懸浮在兩個軸承之間，偏離于底部和頂端同軸線。在底部偏心打開時，地幔內(nèi)部的垂直截面將受到振蕩運動。巖石顆粒將在內(nèi)部和凹面之間被擠壓，粉碎，落下。當(dāng)物料通過破碎機時，它會受到幾個粉碎運動。破碎機的性能和表現(xiàn)很大程度上依賴于行程和板厚度。由于磨損，這些幾何量將在襯板的使用壽命中有所改變。反過來，當(dāng)襯板的幾何形狀變化時，破碎機的表現(xiàn)會發(fā)生變化

43、。除了極少數(shù)例外，這將是一個不利的影響。我們的目的是設(shè)計一種可取的、夠預(yù)測磨損室的幾何形狀的破碎腔。本研究的目的是開發(fā)用于此目的的模型。有了這樣一個模型，將有可能進行模擬，以設(shè)計對磨損不太敏感的破碎機腔。1.2。磨損機理磨損和磨損機制的研究和文獻是非常廣泛的。很多不同的磨損情況已經(jīng)被詳述，但一般四種類型的斷裂被描述為目前正在磨損：疲勞，抗剪連接，微切削和沖擊(vingsbo, 1979).也有次級效應(yīng)，如摩擦熱和腐蝕會影響材料/磨損機制。大部分的研究是在微觀層面。在這項工作中，沒有進一步的關(guān)注被投入到這個主題上。一個用于預(yù)測因磨損而造成的材料損失的模型被archard（1953）提出。在此模型

44、中，它被認為磨損是與壓力和滑動距離成正比的。因此，為了使用archard磨損模型，破碎機的局部壓力和運動需要被了解。一個在archard模型里難以確定的耐磨系數(shù)是，磨料顆粒粉碎過程中的實際磨損。一些成果已為(yao and page, 2001; yao et al. (2000)所獲得，他們已經(jīng)研究了英砂粉碎過程中的磨損。他們在一次粉碎后從微觀水平上研究了表面損傷。為了獲得archard的模型需要的耐磨損系數(shù)，大量反復(fù)的破碎實驗是必要的。然而，他們的研究表明，用于確定磨損，壓力和運動之間關(guān)系的測試設(shè)備，需要類似一個真正的破碎機，將巖石材料粉碎，混合，再粉碎的過程。大量的重復(fù)粉碎實驗后，磨損，

45、幾何形狀測量。為了預(yù)測archard磨損模型磨損幾何形狀組件，壓力和相對運動也必須知道。大量的重復(fù)粉碎實驗后，磨損的幾何形狀將會被測量。為了預(yù)測archard磨損模型磨損幾何形狀組成，壓力和相對運動也必須知道。1.3。測試設(shè)備幾個用于確定磨損系數(shù)的理想檢測設(shè)備，被hutchings（1992）提出。對于粉碎的應(yīng)用，如“pin on disc”測試法，有著磨料的性質(zhì)將在粉碎過程中改變的缺點。這也被yao et al. (2000)，所證實，他們已經(jīng)發(fā)現(xiàn)，通過適當(dāng)?shù)目刂茐毫图羟辛?，可以在材料表面附近形成保護層。這意味著確定一個磨損系數(shù)的測試裝置，需要在類似于一個真正的破碎機的條件下，將材料粉碎，混合，并再次粉碎。這也被用于測量破碎過程