【正文】 grinding and fine grinding separately, coarse grinding is used when the big radial direction feeding, fine grinding the radial feeding the smaller when, finally without into to grinding, to get the surface roughness of surface is very small. The workplace material the workplace material of hardness, plastic and thermal conductivity on the surface roughness of big effect. Large plastic soft material easy jam grinding wheel, thermal conductivity poor heat resistant alloy easy for the abrasive early caving, will lead to increased grinding surface roughness. In addition, because grinding to the high temperature, reasonable use cutting fluids can reduce the grinding of temperature, reduce burns, can also rushed to fall off the grits and scraps, avoid scratch workplace, so as to reduce the surface roughness. Affect the surface of physical and mechanical properties of factors Surface layer cold hardening. The cutting edges obtuse radius increased, and the surface of metal the extrusion of enhanced, plastic deformation intensifies, cold hard to strengthen. After cutting tool knife surface wear increases, the knife surface and after processed surface friction intensified, plastic deformation increase, cold hard to strengthen. Cutting speed increase, cutting tool and workplace role time is shortened, make plastic deformation expand the depth decreases, and cold hard layer depth decreases. After cutting speed increase, heat cutting in the surface layer effect time also shortened, will make cold hard degree increase. Feeding increases, cutting force also increased, and the surface of the metal plastic deformation intensifies, cold hard effect is strengthening. The workplace material of plastic is larger and the cold hard phenomenon the serious. Surface layer material metallographic position change. When cutting the heat was processing surface temperature of phase change after more than temperature, the surface of the metal microstructure will change. Grinding burns when a surface temperature of phase change to millers temperature above, metal surface microstructure occurred change, make the surface of the metal strength and hardness of the lower, and with residual stress produce appear even microscopic cracks, this phenomenon is called grinding burns. Improve grinding burns grinding heat caused by grinding way is the root of the burn, so improving grinding burns by two ways: one is as far as possible to reduce the generation of grinding heat。 The speed increase, a surface temperature will increase grinding zone, but due to the hot action time reduced, so can reduce the burn. The workplace material the workplace material grinding zone of the influence of the temperature of depends primarily on its hardness and strength, toughness and thermal conductivity. The workplace material hardness, the higher the strength, toughness, the bigger the grinding work when the more consumption, the quantity of heat that produced the more, the easy generation burns。 振動(dòng)使工藝系統(tǒng)的各種成形運(yùn)動(dòng)受到干擾和破壞，使加工表面出現(xiàn)振紋，增大表面粗糙機(jī)械專業(yè)中英文文獻(xiàn)翻譯 度值，惡化加工表面質(zhì)量。另外，刀具的前、后刀面、切削刃本身的粗糙度直接影響加工表面的粗糙度，因此，提高刀具的刃磨質(zhì)量，使刀具前后刀面、切削刃的粗糙度值應(yīng)低于工件的粗糙度值的 1~2級。加工脆性材料時(shí)其切屑呈碎粒狀，由于切屑的崩碎而在加工表面留下許多麻點(diǎn)使表面粗糙。 切削條件對工件表面質(zhì)量的影響 與切 削條件有關(guān)的工藝因素，包括切削用量、冷卻潤滑情況。 切削速度對表面粗糙度的影響 一般在粗加工 選用低速車削，精加工選用高速車削可以減小表面粗糙度。砂輪的硬度應(yīng)大小合適，其半鈍化期愈長愈好；砂輪的硬度太高，磨削時(shí)磨粒不易脫落，使 加工表面受到的摩擦、擠壓作用加劇，從而增加了塑性變形，使得表面粗糙度增大，還易引起燒傷；但砂輪太軟，磨粒太易脫落，會(huì)使磨削作用減弱，導(dǎo)致表面粗糙機(jī)械專業(yè)中英文文獻(xiàn)翻譯 度增加，所以要選擇合適的砂輪硬度。增大磨削深度和縱向進(jìn)給量，工件的塑性變形增大，會(huì)導(dǎo)致表面粗糙度值增大。塑性大的軟材料容易堵塞砂輪，導(dǎo)熱性差的耐熱合金容易使磨料早期崩落，都會(huì)導(dǎo)致磨削表面粗糙度增大。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)。工件材料的塑性愈大 ,冷硬現(xiàn)象就愈嚴(yán)重。改善磨削燒傷的途徑磨削熱是 造成磨削燒傷的根源 ,故改善磨削燒傷由兩個(gè)途徑 :一是盡可能地減少磨削熱的產(chǎn)生 。產(chǎn)生殘余應(yīng)力的原因 :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 。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損壞形式。當(dāng)采用中等或中等偏低的切削速度切削塑性材料時(shí)，在前刀面上容易形成 硬度很高的積屑瘤，它可以代替刀具進(jìn)行切削，但狀態(tài)極不穩(wěn)定，機(jī)械專業(yè)中英文文獻(xiàn)翻譯 積屑瘤生成、長大和脫落將嚴(yán)重影響加工表面的表面粗糙度值。產(chǎn)生磨削燒傷時(shí)，加工表面常會(huì)出現(xiàn)黃、褐、紫、青等燒傷色，這是磨削表面在瞬時(shí)高溫下的氧化下膜顏色。干磨時(shí)很容易產(chǎn)生這種現(xiàn)象。具體可采用下列措施： 合理選擇磨削用量 不能采用太大的磨削深度，因?yàn)楫?dāng)磨削深度增加時(shí)，工件的塑性變形會(huì)隨之增加，工件表面及里層的溫度都將升高，燒傷亦會(huì)增加；工件速度增加，磨削區(qū)表面溫度會(huì)增高，但由于熱作用時(shí)間減少，因而可減輕燒傷。 冷卻條件為降低磨削區(qū)的溫度，在磨削時(shí)廣泛采用切削液冷卻。 疲勞強(qiáng)度對表面質(zhì)量的影響 在交變載荷作用 ,表面粗糙度的凹谷部位容易引起應(yīng)力集中產(chǎn)生疲勞紋?？刮g性就愈差。由于零件表面存在著表面粗糙度，當(dāng)兩個(gè)零件的表面開始接觸時(shí)，接觸部分集中在其波峰的頂部，因此實(shí)際接觸面積遠(yuǎn)遠(yuǎn)小于名義接觸面積，并且表面粗糙度越大，實(shí)際接觸面積越小。 表面層的冷作硬化可使表面層的硬度提高，增強(qiáng)表面層的接觸剛度，從而降低接觸處的彈性、塑性變形，使耐磨性有所提高。并且表面粗糙度越大，表面劃痕越深，其抗疲勞破壞能力越差。適度的加工硬化能阻止已有裂紋的擴(kuò)展和新裂紋的產(chǎn)生，提高零件的疲勞強(qiáng)度；但加工硬化過于嚴(yán)重會(huì)使零件表面組織變脆，容易出現(xiàn)裂紋，從而使疲勞強(qiáng)度降低。殘余壓應(yīng)力使表面組織致密，腐蝕性介質(zhì)不易侵入，有助于提高表面的耐腐蝕能力；殘余拉應(yīng)力的對零件耐腐蝕性能的影響則相反。 在過盈配合中，如果表面硬化嚴(yán)重，將可能造成表面層金屬與內(nèi)部金屬脫落的現(xiàn)象，從而破壞配合性質(zhì)和配合精度。