【正文】 落而加劇零件的磨損。在外力作用下，波峰接觸部分將產(chǎn)生很大的壓應(yīng)力。表面層的殘余拉應(yīng)力會產(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。表面粗糙度值愈大 ,表面的紋痕愈深 ,紋底半徑愈小 ,抗疲勞破壞的能力就愈差。為了使切削液能噴注到工件表面上，通常增加切削液的流量和壓力并采用特殊噴嘴，并在砂輪上安裝帶有空氣擋板的切削液噴嘴，這樣既可加強(qiáng)冷卻作用，又能減輕高速旋轉(zhuǎn)砂輪表面的高壓附著作用，使切削液順利地噴注到磨削區(qū)。 工件材料 工件材料對磨削區(qū)溫度的影響主要取決于它的硬度、強(qiáng)度、韌性和熱導(dǎo)率。 如果磨削表面層溫度超過相變溫度，但有充分的切削液對其進(jìn)行冷卻，則磨削表面層將急冷形成二次淬火馬氏體，硬度比回火馬氏體高，不過該表面層很薄，只有幾微米厚，其下為硬度較低的回火索氏體和索氏體，使表面層總的硬度仍然降低，稱為淬火燒傷。不同的燒傷色，表明工件表面受到的燒傷程度不同。另外，在切削過程中由于切屑和前刀面的強(qiáng)烈摩擦作用以及撕裂現(xiàn)象，還可能在加工表面上產(chǎn)生鱗刺，使加工表面的粗糙度增加。在交變載荷作用下 ,機(jī)器零件表面上的局部微觀裂紋 ,會因拉應(yīng)力的作用使原生裂紋擴(kuò)大 ,最后導(dǎo)致零件斷裂。切削加工中 ,切削區(qū)會有大量的切削熱產(chǎn)生 。二是改善冷卻條件 ,盡量使產(chǎn)生的熱量少傳入工件。 表面層材料金相組織變化。切削速度增大 ,刀具與工件的作用時間縮 短 ,使塑性變形擴(kuò)展深度減小 ,冷硬層深度減小。 另外，由于磨削溫度高，合理使用切削液既可以降低磨削區(qū)的溫度，減少燒傷，還可以沖去脫落的磨粒和切屑，避免劃傷工件，從而降低表面粗糙度值。徑向進(jìn)給量增加，磨削過程中磨削力和磨削溫度都會增加，磨削表面塑性變形程度增大，從而會增大表面粗糙度值。砂輪的修整質(zhì)量越高，砂輪表面的切削微刃數(shù)越多、各切削微刃的等高性越好，磨削表面的粗糙度越小。 在中速切削塑性材料時，由于容易產(chǎn)生積屑瘤，且塑性變形較大，因此加工后零件表面粗糙度較大。中、低速加工塑性材料時，容易產(chǎn)生積屑瘤和鱗刺，所以，提高切削速度，可以減少積屑瘤和鱗刺，減小零件已加工表面粗糙度值；對于脆性材料，一般不會形成積屑瘤和鱗刺，所以，切削速度對表面粗糙度基本上無影響。 一般韌性較大的塑性材料，加工后表面粗糙度較大，而韌性較小的塑性材料，加工后易得到較小的表面粗糙度。 切削液對表面質(zhì)量的影響 切削液的冷卻和潤滑作用能減小切削過程中的界面摩擦，降低切削區(qū)溫度，使切削層金屬表面的塑性變形程度下降，抑制積屑瘤和鱗刺的產(chǎn)生，在生產(chǎn)中對于不同材料合理選用切削液可大大減小工件表面粗糙度。 刀具幾何參數(shù)、材料和刃磨質(zhì)量對表面質(zhì)量的影響 刀具的幾何參數(shù)中對表面粗糙度影響最大主要是副偏角、主偏角、刀尖圓弧半徑。 Thermal conductivity of poor material, also easy to appear in the grinding burns. The choice of high hardness of the grinding wheel grinding wheel, passivated grits is not easy to fall off, easy to produce burns, so with soft grinding wheel is better。 2 it is improved cooling condition, make as far as possible the quantity of heat to produce less workplace. The correct choice grinding wheel reasonable choice of cutting dosages improved cooling conditions. Surface layer residual stress. Produce residual stress of reason: cutting in processing the metal layer and the surface when there were plastic deformation occurs, the surface of the metal to hematocrit increase。 The hardness of the grinding wheel is too high, grinding mill is not easy to fall off when grain, make processing surface is of friction, extrusion action intensifies, thus increasing the plastic deformation, making the surface roughness increases, also easy cause burns。 For brittle material, general won39。 Processing plastic materials, the cutting tools for metal extrusion produced plastic deformation, and the cutting tool and workplace forced separation of the torn scraps effect, make the surface roughness value increase. The workplace material tenacity the better, metal, plastic deformation, the bigger the processing surface is the more the rough. Processing brittle material in the chip broken granular, due to the collapse in broken and endows the machined surface left many pitted surface roughness. General toughness large plastic materials, processing after large surface roughness, and toughness of smaller plastic materials, processing to get smaller after the surface roughness. For the same kind of material, the greater the grain size of the organization, the larger the surface roughness. Therefore, in order to reduce the surface roughness, often in cutting processing of 機(jī)械專業(yè)中英文文獻(xiàn)翻譯 material before quenching and tempering or is the fire of treatment to obtain homogeneous fine grain organization and high hardness. Cutting condition the influence on the quality of the surface And cutting condition of the relevant process factors, including cutting dosages, cooling lubrication. In low speed processing plastic materials, easy to produce the develop and scales thorn, so, improve the cutting speed, can reduce the develop and scales thorn, decreasing part already the surface roughness value。 But if too fine granularity, processing to jam wheel it will increase the surface roughness, also easy to produce the ripple and cause burns. The hardness of the grinding wheel should be the right size, its half the longer the better passivation period。 But the low speed, workplace and grinding wheel contact time long, to the quantity of heat of the increasing, opposite will increase the roughness, may also increase surface burn. Increase grinding depth and longitudinal feeding, the plastic deformation increase, will lead to the surface roughness value increase. Radial feeding 機(jī)械專業(yè)中英文文獻(xiàn)翻譯 increase, the grinding process grinding force and grinding temperature will increase, grinding surface plastic deformation degree increase, which will increase the surface roughness. To guarantee the machining quality in the premise of grinding efficiency increase, will require a higher surface the coarse