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1、 1 機(jī)械專業(yè)外語文獻(xiàn)翻譯 系 別 機(jī)電工程 系 專 業(yè) 機(jī)械設(shè)計(jì)制造及其自動(dòng)化 班 級(jí) 學(xué)生姓名 學(xué) 號(hào) 日 期 2014.6.10 1 The Surface Quantity While Machine Processes A.the machine processes the surface quantity to use the influence of the function to the machine (A)The surface quantity to bear to whet the sexual influence 1. Rough degree of surface
2、to bear to whet the sexual influence The rough degree of surface is very big to the influence that the spare parts surface wear away.Say a value of surface generally more small, it wears away sex more good.But rough degree of surface the value is too small, lubricant not easy storage, contact of the
3、 noodles easy occurrence the member glues to connect, wearing away to increase on the contrary.Therefore, the rough degree that contact face have a the best value, it is worth to have something to do with the work circumstance of the spare parts, working to carry the lotus enlargement, wore away the
4、 quantity aggrandizement in the early years, rough degree of surface the best value also enlargement. 2. The surface is cold to make to harden to bear to whet the sexual influence Process the surface cold to make to harden to make rub the vice- surface layer the metals of show minute details the deg
5、ree of hardness exaltation, past can make bear to whet the sex exaltation generally.But is also not cold to make to harden the degree more high, bear to whet sex more high, this is because excessively cold make to harden and will cause the excesssive loose of the metals organization loose, even appe
6、ar the crack and surface layer metals peeling off, make bear to whet sex to descend. (B)The surface influence of the quantity upon the tired strength The tired breakage that metals produce after be subjected to hand over to change to carry the lotus function usually takes place under the cold and ha
7、rd layer of the spare parts surface and surfaces, therefore the surface quantity of the spare parts affects to the tired strength very greatly. 1. The surface influence of the rough degree upon the tired strength At hand over to change to carry the lotus function under, the surface part of the cave
8、valley of the rough degree causes easily should the dint concentration, produce the tired crack.A value of surface is more big, the crackle of the surface is more deep, the crackle bottom radius is more small, the anti- tired breakage bottom ability is more bad. 2. Remaining dint, cold make to harde
9、n to the influence of the tired strength Remaining dint is very big to the spare parts influence of the tired strength.The surface layer remaining pull should the dint will make tired crack extend, accelerating the tired breakage；But the surface layer remaining should the dint can keep tired crack f
10、rom expand, defer tired breakage of creation. 1 2Surface the cold and hard general companion contain remaining of should the creation of the dint, can keep the crack creation from combine the arrestment already has the crack to expand, to raise the tired strength beneficial. (C) the surface quantity
11、 to bear the eclipse influence The spare parts bears the eclipse to be decided by the rough degree of surface to a large extent.A value of surface is more big, accumulating the causticity material in the then cave valley more many.The anti- eclipse is more bad. Remaining of the surface layer pull sh
12、ould the dint will produce should the dint decay to open the rift , lower the spare parts to bear to whet sex, but Residual stress press should the dint then can preventfrom should dint decay open the rift . (D)The surface quantity to match with the influence of the quantity A size for be worth of s
13、urface will affect the match quantity of the match surface.Match with for the cleft, a value conference make wear away the enlargement, the cleft enlarge, the match property that break the request.For lead the over match, assemble process in a the convex peak of part of surfaces is push even, actual
14、 lead the amount of over let up, lowering the match the conjunction strength of the a. B. the influence surface factor of the rough degree (A)Slice to pare to process to affect the surface factor of the rough degree 1. The knife has several shapes to reply to reflect 2. The property of a material of
15、 work 3. Slice to pare the dosage (B)Whet to pare to process to affect the surface factor of the rough degree The influence whets to pare the rough main factor of surface to have: The degree of hardness, emery wheel of a degree, emery wheel of the emery wheel fix whole, whet to pare the speed and wh
16、et to pare the path to enter to whet number of times, the work a circumference for quantity and light to enter to the speed and stalks to enter to the quantity and cool off the lubrication liquid. C. affect the factor of process the surface layer physics machine function In slice pare process, the w
17、ork piece because of being subjected to slice to pare the dint and slice the function of pare the heat, make the physics machine the function creation of the surface layer metals change, the variety of the most is variety and Residual stress s that the variety, gold that the surface layer metals sho
18、ws minute details the degree of hardness organizes mutually should the creation of the dint.Because whetting to pare to process the mold produce transforms and slices to pare the hot ratio knife blade to slice to pare serious, as a result whet to pare to process to process behind the surface layer v
19、ariety of above-mentioned three physicses machine function and would be very big. (A)The surface layer is cold to make the hardening 1. Cold make to harden The machine processes the process in because of slicing to pare the output mold of the dint function to transform, make the Crystal grain space
20、distort, mutation, a creation shears to slice to slip to move, grain of Crystal grain drive make longer to turn with fiber, even broken up, these would make the surface layer metals of degree of hardnesses and strength raise, this kind of phenomenon be called cold make the 1 3hardening.( or be calle
21、d to enhance)The result that the surface layer metals enhance, will enlarge the resistance that metals transform, let up the mold of the metals, the physical property of the metals also will take place the variety. 2. Affect cold main factor that make to harden Slice to pare a radius of the blade bl
22、untness to enlarge, to the squeeze of the surface layer metals function to build up, the mold transforms to turn worse, causing the cold and hard to build up.After knife have the knife faces to wear away the aggrandizement, empress the knife face with is process surface of friction turn worse, the m
23、old transform the aggrandizement, causing the cold and hard to build up. Slice to pare the speed aggrandizement, the knife has to shorten with function time of the work piece, making mold transform expand the depth to let up, the cold and hard layer depth let up.After slicing to pare the speed aggra
24、ndizement, slice to pare the heat on a surface of work layer of function time also shorten the joy, will make the cold and hard degree increment.Enter to enlarge for quantity, slice to pare the dint to also enlarge, surface layer the mold of the metals transforms to turn worse, the cold and hard fun
25、ction strengthen. The mold of a material of work is more big, the cold and hard phenomenon is more serious. (B)The surface layer remaining should dint 1. Produce remaining of should the reason of the dint a. Slice to pare have the mold to transform the occurrence in process the surface metals layer,
26、 make the metal ratio of surface permit the enlargement.Because the mold transform only creation in the surface layer metals, but the ratio of the surface layer metals permits the aggrandizement, the physical volume inflation, the mile layer that want to be subjected to connect with each other with
27、it inevitably metals of arrestment, so produced in the surface metals layer Remaining dint, but produce the remaining to pull in in the layer metals should dint. b. Slice to pare to process medium, slice and pare the area and there will be to slice to pare the hot creation in great quantities. c. Th
28、e different gold organizes the density of have the dissimilarity mutually, also having the different ratio to permit.If the surface layer metals produced the variety that gold mutually organize, the variety that the surface layer metals compares to permit want to be subjected to by all means with it
29、s the bar of the base body metals for connect with each other, as a result there is Remaining dint creation. 2. The end work preface of main work surface of spare parts processes the choice of method The end work preface of main work surface of spare parts processes the method to choose to the pass
30、importance, because the end work preface is should work remaining of surface leave should the dint will affect the usage function of the machine parts directly. Choose the main end work preface of surface of work of spare parts processes the method, must consider the concrete work condition and poss
31、ible breakage forms of the surface of main work of that spare partses. At hand over to change to carry the lotus function under, superficially partial tiny 1 4view crack of machine parts, meeting because of pull should the function of the dint make living at first the crack extension, causing spare
32、parts split finally.The spare parts resists from the exaltation tired breakage of angle consider, the end work preface of that surface shoulds choose and can produce the remaining to press in that surface should the dint process the method. 1 5機(jī)械加工表面質(zhì)量 A、機(jī)械加工表面質(zhì)量對(duì)機(jī)器使用性能的影響 （ A）表面質(zhì)量對(duì)耐磨性的影響 1. 表面粗糙度對(duì)
33、耐磨性的影響 表面粗糙度對(duì)零件表面磨損的影響很大。一般說表面粗糙度值愈小，其磨損性愈好。但表面粗糙度值太小，潤滑油不易儲(chǔ)存，接觸面之間容易發(fā)生分子粘接，磨損反而增加。因此，接觸面的粗糙度有一個(gè)最佳值，其值與零件的工作情況有關(guān)，工作載荷加大時(shí)，初期磨損量增大，表面粗糙度最佳值也加大。 2. 表面冷作硬化對(duì)耐磨性的影響 加工表面的冷作硬化使摩擦副表面層金屬的顯微硬度提高，故一般可使耐磨性提高。但也不是冷作硬化程度愈高，耐磨性就愈高，這是因?yàn)檫^分的冷作硬化將引起金屬組織過度疏松，甚至出現(xiàn)裂紋和表層金屬的剝落 ，使耐磨性下降。 （ B）表面質(zhì)量對(duì)疲勞強(qiáng)度的影響 金屬受交變載荷作用后產(chǎn)生的疲勞破壞往往發(fā)
34、生在零件表面和表面冷硬層下面，因此零件的表面質(zhì)量對(duì)疲勞強(qiáng)度影響很大。 1. 表面粗糙度對(duì)疲勞強(qiáng)度的影響 在交變載荷作用下，表面粗糙度的凹谷部位容易引起應(yīng)力集中，產(chǎn)生疲勞裂紋。表面粗糙度值愈大，表面的紋痕愈深，紋底半徑愈小，抗疲勞破壞底能力就愈差。 2. 殘余應(yīng)力、冷作硬化對(duì)疲勞強(qiáng)度的影響 余應(yīng)力對(duì)零件疲勞強(qiáng)度的影響很大。表面層殘余拉應(yīng)力將使疲勞裂紋擴(kuò)大，加速疲勞破壞；而表面層殘余應(yīng)力能夠阻止疲勞裂紋的擴(kuò)展， 延緩疲勞破壞的產(chǎn)生。 表面冷硬一般伴有殘余應(yīng)力的產(chǎn)生，可以防止裂紋產(chǎn)生并阻止已有裂紋的擴(kuò)展，對(duì)提高疲勞強(qiáng)度有利。 （ C)表面質(zhì)量對(duì)耐蝕性的影響 零件的耐蝕性在很大程度上取決于表面粗糙度。
35、表面粗糙度值愈大，則凹谷中聚積腐蝕性物質(zhì)就愈多。抗蝕性就愈差。 表面層的殘余拉應(yīng)力會(huì)產(chǎn)生應(yīng)力腐蝕開裂，降低零件的耐磨性，而殘余壓應(yīng)力則能防止應(yīng)力腐蝕開裂。 （ D）表面質(zhì)量對(duì)配合質(zhì)量的影響 表面粗糙度值的大小將影響配合表面的配合質(zhì)量。對(duì)于間隙配合，粗糙度值大會(huì)使磨損加大，間隙增大，破壞了要求的配合性質(zhì)。對(duì)于過盈配合 ，裝配過程中一部分表面凸峰被擠平，實(shí)際過盈量減小，降低了配合件間的連接強(qiáng)度。 B、影響表面粗糙度的因素 （ A）切削加工影響表面粗糙度的因素 1. 刀具幾何形狀的復(fù)映 2. 工件材料的性質(zhì) 3. 切削用量 1 6（ B）磨削加工影響表面粗糙度的因素 影響磨削表面粗糙的主要因素有：
36、砂輪的粒度、砂輪的硬度、砂輪的修整 、磨削速度 、磨削徑向進(jìn)給量與光磨次數(shù) 、工件圓周進(jìn)給速度與軸向進(jìn)給量 、冷卻潤滑液 。 C、影響加工表面層物理機(jī)械性能的因素 在切削加工中，工件由于受到切削力和切削熱的作用，使表面層金屬 的物理機(jī)械性能產(chǎn)生變化，最主要的變化是表面層金屬顯微硬度的變化、金相組織的變化和殘余應(yīng)力的產(chǎn)生。由于磨削加工時(shí)所產(chǎn)生的塑性變形和切削熱比刀刃切削時(shí)更嚴(yán)重，因而磨削加工后加工表面層上述三項(xiàng)物理機(jī)械性能的變化會(huì)很大。 （ A）表面層冷作硬化 1. 冷作硬化 機(jī)械加工過程中因切削力作用產(chǎn)生的塑性變形，使晶格扭曲、畸變，晶粒間產(chǎn)生剪切滑移 ,晶粒被拉長和纖維化，甚至破碎，這些都會(huì)
37、使表面層金屬的硬度和強(qiáng)度提高，這種現(xiàn)象稱為冷作硬化 (或稱為強(qiáng)化 )。表面層金屬強(qiáng)化的結(jié)果，會(huì)增大金屬變形的阻力，減小金屬的塑性，金屬的物理性 質(zhì)也會(huì)發(fā)生變化。 2. 影響冷作硬化的主要因素 切削刃鈍圓半徑增大，對(duì)表層金屬的擠壓作用增強(qiáng)，塑性變形加劇，導(dǎo)致冷硬增強(qiáng)。刀具后刀面磨損增大，后刀面與被加工表面的摩擦加劇，塑性變形增大，導(dǎo)致冷硬增強(qiáng)。 切削速度增大，刀具與工件的作用時(shí)間縮短，使塑性變形擴(kuò)展深度減小，冷硬層深度減小。切削速度增大后，切削熱在工件表面層上的作用時(shí)間也縮短樂，將使冷硬程度增加。進(jìn)給量增大，切削力也增大，表層金屬的塑性變形加劇，冷硬作用加強(qiáng)。 工件材料的塑性愈大，冷硬現(xiàn)象就愈嚴(yán)
38、重。 （ B）表面層殘余應(yīng)力 1. 產(chǎn)生殘余應(yīng)力的原 因 a. 切削時(shí)在加工表面金屬層內(nèi)有塑性變形發(fā)生，使表面金屬的比容加大。由于塑性變形只在表層金屬中產(chǎn)生，而表層金屬的比容增大，體積膨脹，不可避免地要受到與它相連的里層金屬的阻止，因此就在表面金屬層產(chǎn)生了殘余應(yīng)力，而在里層金屬中產(chǎn)生殘余拉應(yīng)力。 b. 切削加工中，切削區(qū)會(huì)有大量的切削熱產(chǎn)生 。 c. 不同金相組織具有不同的密度，亦具有不同的比容。如果表面層金屬產(chǎn)生了金相組織的變化，表層金屬比容的變化必然要受到與之相連的基體金屬的阻礙，因而就有殘余應(yīng)力產(chǎn)生。 2. 零件主要工作表面最終工序加工方法的選擇 零件主要工作表面最終工序加工方法的選擇至關(guān)重要，因?yàn)樽罱K工序在該工作表面留下的殘余應(yīng)力將直接影響機(jī)器零件的使用性能。 選擇零件主要工作表面最終工序加工方法，須考慮該零件主要工作表面的具體工作條件和可能的破壞形式。 在交變載荷作用下，機(jī)器零件表面上的局部微觀裂紋，會(huì)因拉應(yīng)力的作用使原生裂紋擴(kuò)大，最后導(dǎo)致零件斷裂。從提高零件抵抗疲勞破壞的角度考慮，該表面最終工序應(yīng)選擇能在該表面產(chǎn)生殘余壓應(yīng)力的加工方法。
外文翻譯--機(jī)械加工表面質(zhì)量
