外文翻譯--高速研磨技術的應用與展望

1、<p>　　外文翻譯：英文+中文 16頁 5909字數(shù)</p><p>　　High-speed grinding ---applications and future technology</p><p>　　M.J. Jackson,*, C.J. Davis, M.P. Hitchhiker, B. Mills</p>&

2、lt;p><b>　　Abstract</b></p><p>　　The basic mechanisms and the applications for the technology of high-speed grinding with CBN grinding wheels are presented. In addition to developments in proce

3、ss technology associated with high-speed machining, the grinding machine, coolant system, and the grinding tool also need to adapt to high-speed machining. Work piece-related factors inurning the results of machining are

4、 also discussed. The paper concludes with a presentation of current research and future developments in the area of high</p><p>　　1. Introduction</p><p>　　More than 25 years of high-speed grindi

5、ng have expanded the field of application for grinding from classical finish machining to high-performance machining. High-speed grinding offers excellent potential for good component quality combined with high productiv

6、ity. One factor behind the innovative process has been the need to increase productivity for conventional finishing processes. In the course of process development it has become evident that high-speed grinding in combin

7、ation with preliminar</p><p>　　2. Theoretical basis of high-speed grinding</p><p>　　In view of the random distribution of cutting edges and cutting-edge shapes, statistical methods are applied t

8、o analyses the cutting mechanism in grinding. The mean unreformed chip thickness, hcu, and the mean chip length, lcu, are employed as variables to describe the shape of the chip. The unreformed chip thickness is dependen

9、t on the static density of cutting edges, Cstat, and on the geometric and kinematics variables [1,2]:</p><p><b>　　(1)</b></p><p>　　where Vw is the work piece speed, VS the grinding w

10、heel speed, ae the depth of cut, deq the equivalent grinding wheel diameter, and α，β，γ are greater than zero. On the basis of this relationship, it can be established that an increase in the cutting speed, assuming all o

11、ther conditions are constant, will result in a reduction in the unreformed chip thickness. The work piece material is machined with a larger number of abrasive grain contacts. At the same time, the number of cutting edge

12、s involve</p><p>　　of the work piece to be machined.</p><p>　　As the cutting speed increases, the quantity of thermal energy that is introduced into the work piece also increases. An increase in

13、 cutting speed is not normally accompanied by a proportional reduction in the tangential grinding force, and thus results in an increase in process power. Reducing the length of time the abrasive grain is in contact with

14、 the work piece can reduce the quantity of heat into the work piece. An increase in the machining rate of the process is necessary for this to happe</p><p>　　Experimental results [3] illustrate that increasi

15、ng the cutting speed by a factor of two while maintaining the same metal removal rate leads to a reduction in the tangential force but, unfortunately, leads to an increase in the amount of work done. Owing to constant gr

16、inding time, there is an increase in the process energy per work piece and, subsequently, in the total thermal energy generated. When the material removal rate is also increased the rising tangential force results in a f

17、urther incr</p><p>　　There are three fields of technology that have become established for high-speed grinding. These are</p><p>　　1. High-speed grinding with CBN grinding wheels.</p><

18、;p>　　2. High-speed grinding with aluminum oxide grinding wheels.</p><p>　　3. Grinding with aluminum oxide grinding wheels in conjunction with continuous dressing techniques (CD grinding).</p><p

19、>　　Material removal rates resulting in a super proportional increase in productivity for component machining have been achieved for each of these fields of technology in industrial applications [4,5] (Fig. 1). High eq

20、uivalent chip thickness of between 0.5 and 10 mm are a characteristic feature of high-speed grinding. CBN high-speed grinding is employed for a large proportion of these applications. An essential characteristic of this

21、technology is that the performance of CBN is utilized when high cu</p><p>　　3. Grinding tools for high-speed grinding</p><p>　　CBN grinding tools for high-speed machining are subject to special

22、requirements regarding resistance to fracture and wear. Good damping characteristics, high rigidity, and good thermal conductivity are also desirable. Such tools normally consist of a body of high mechanical strength and

23、 a comparably thin coating of abrasive attached to the body using a high-strength adhesive. The suitability of cubic boron nitride as an abrasive material for high-speed machining of ferrous materials is attribute</p&

24、gt;<p>　　High cutting speeds are attainable above all with metal bonding systems (Fig. 2). One method that uses such bonding systems is electroplating, where grinding wheels are produced with a single-layer coatin

25、g of abrasive CBN grain material. The electro-deposited nickel bond displays outstanding grain retention properties. This provides a high-level grain projection and large chip spaces. Cutting speeds of 280 m s-1 are poss

26、ible [6]. The service life ends when the abrasive layer wears out.</p><p>　　The high roughness of the cutting surfaces of electroplated CBN grinding wheels has disadvantageous effects. The high roughness is

27、accountable to exposed grain tips that result from different grain shapes and grain diameters. Although electroplated CBN grinding wheels are not considered to be dressable in the conventional sense, the resultant workpi

28、ece surface roughness can nevertheless be influenced within narrow limits by means of a so-called touch-dressing process. This involves removing the </p><p>　　Multi-layer bonding systems for CBN grinding whe

29、els include sintered metal bonds, resin bonds, and vitrified bonds. Multi-layer metal bonds possess high bond hardness and wear resistance. Profiling and sharpening these tools is a complex process, however, on account o

30、f their high mechanical strength. Synthetic resin bonds permit a broad scope of adaptation for bonding characteristics. However, these tools also require a sharpening process after dressing. The potential for practical a

31、pplication o</p><p>　　The selection of the appropriate grade of vitrified CBN grinding wheel for high-speed grinding is more complicated than for aluminium oxide grinding wheels. Here, the CBN abrasive grain

32、 size is dependent on specific metal removal rate, surface roughness requirement, and the equivalent grinding wheel diameter. As a starting point when specifying vitrified CBN wheels, Fig. 4 shows the relationship betwee

33、n CBN abrasive grain size, equivalent diameter, and specific metal removal rate for outside dia</p><p>　　vitrified bond used in the grinding wheel. Table 2 shows the wheel grade required for a variety of wor

34、kpiece materials that are based on crankshaft and camshaft grinding operations. </p><p>　　The stiffness of the component being ground has a significant effect on the workpiece/wheel speed ratio. Fig. 5 demon

35、strates the relationship between this ratio and the stiffness of the component. Steels such as AISI 1050 can be ground in the hardened and the soft state. Hardened 1050 steels are in the range 62±68 HRc. They are bu

36、rn sensitive and as such wheels speeds are limited to 60 m sÿ1. The standard structure contains the standard bonding system up to 23 vol.%. Whereas the abrasive grain v</p><p>　　In addition to the need

37、to select the appropriate bonding system for grinding wheels in accordance with the requirements of the application concerned, the strength of the body of the grinding wheel requires optimization with high cutting speeds

38、. In the case of very high cutting speeds, conventional grinding wheel designs involving a rectangular body and a bore often leads to excessive and irregular extensions of the body and cracking of the abrasive coating. I

39、n order to eliminate the possibility</p><p>　　CBN [8,9] and electroplated CBN grinding wheels [10].</p><p>　　4. High-speed machine tool development</p><p>　　The advantages of high-s

40、peed CBN grinding can only be realised in an effective manner if the machine tool is adapted to operate at high cutting speeds. In order to attain very high cutting speeds, grinding wheel spindles and bearings are requir

41、ed to operate at speeds in the order of 20 000 rpm. The grinding wheel/spindle/motor system must run with extreme accuracy and minimum vibration in order to minimise the level of dynamic process forces. Therefore, a high

42、 level of rigidity is required for t</p><p>　　Another important consideration is the level of drive power required when increases in rotational speed become considerable. The required total output is compose

43、d of the cutting power, Pc, and the power loss, Pl:</p><p>　　The cutting power is the product of the tangential grinding force and the cutting speed:</p><p>　　The power loss of the drive is comp

44、rised of the idle power of the spindle, PL, and power losses caused by the coolant, PKSS, and by spray cleaning of the grinding wheel, PSSP, thus</p><p>　　The power measurements shown in Fig. 6 confirm the i

45、nfluence of the effect of cutting speed on the reduction of cutting power. However, idling power has increased quite significantly. The grinding power, Pc, increases by a relatively small amount when the cutting speed in

46、creases and all other grinding parameters remain constant. However, this means that the substantial power requirement that applies at maximum cutting speeds results from a strong increase in power is due to rotation of t

47、he grind</p><p>　　The quantities and pressures of coolant supplied to the grinding wheel and the wheel cleaning process are the focus of attention by machine tool designers. This is shown in Fig. 7 [11]. The

48、 power losses associated with the rotation of the grinding wheel are supplemented by losses associated with coolant supply and wheel cleaning. The losses are dependent on machining parameters implying that machine settin

49、gs and coolant supply need to be optimised for high-speed grinding.</p><p>　　In addition to the advantage of effectively reducing the power required for grinding, optimisation of the coolant supply also offe

50、rs ecological benefits as a result of reducing the quantities of coolant required. Various methods of coolant supply are available such as the free-flow nozzle that is conventionally used, the shoe nozzle that ensures `r

51、educed quantity lubrication', and the mixture nozzle that ensures `minimum quantity lubrication'. The common task is to ensure that an adequate supply</p><p>　　A shoe nozzle, or supply through the gr

52、inding wheel, enables coolant to be directed into the workpiece±wheel contact zone. A substantial reduction in volumetric flow can be achieved in this way. In comparison to the shoe nozzle, supply through the grindi

53、ng wheel requires more complex design and production processes for the grinding wheel and fixtures. An advantage of this supply system is that it is independent of a particular grinding process [13]. Both systems involve

54、 a drastic reduction in su</p><p>　　5. Factors affecting quality</p><p>　　The aim of high-speed CBN grinding is to substitute conventional machining operations such as milling, turning, and surf

55、ace broaching. The high-speed grinding process focuses on machining large volumes of material in the shortest possible time. This may lead to workpiece quality becoming impaired as the equivalent chip thickness increases

56、 in proportion to grinding forces [10,15] The machine tool must be able to absorb such large forces. It is possible to reduce the amount of heat in the grinding</p><p>　　高速研磨技術的應用與展望</p><p><

57、b>　　摘要</b></p><p>　　基本原理和應用技術在高速研磨上占有相當?shù)牡匚?。除了發(fā)展高速切削的相關技術外，磨床、冷卻系統(tǒng)、磨輪也需要適應高速加工。文章最后提出了當前和今后的研究發(fā)展方面的高速磨削，發(fā)展用立方淡化硼砂輪的高速磨床。</p><p><b>　　引子</b></p><p>　　經(jīng)過多年的高速機的發(fā)展，

58、其應用領域不斷擴大，從古典磨削加工工藝，一直到完成高性能機械加工過程中。高速磨削發(fā)揮了重要作用，而且生產(chǎn)出的產(chǎn)品優(yōu)質(zhì)高產(chǎn)。其中一個因素是在創(chuàng)新的過程中，必須提高生產(chǎn)力的常規(guī)整理過程。在發(fā)展過程中顯然高速磨削加工工藝過程與初步理論基礎的配合接近完成，使配置過程順序與新的高性能能力提高。同時采用適當?shù)墓ぞ邫C、研磨機，還有可能擴大到高性能軟材料切削機的發(fā)展。</p><p>　　首先，在討論原理的基礎研究過程中，磨軟材

59、料的有關配置工具也需要達到要求，實施有效的環(huán)保制冷系統(tǒng)，調(diào)查工作也同時是適合高速磨削技術影響的一個變數(shù)。</p><p><b>　　高速磨削的理論基礎</b></p><p>　　由于隨機分配切割邊緣和尖銳部分的隨機分布，得以使統(tǒng)計分析的方法應用于切割機原理。使得平均厚度改變，hcu ，平均長度的控制，都被認為是造型的變數(shù)用來描述的。改變的厚度取決于Cstat和幾何

60、構造等變量，相當于：</p><p>　　這些的工作是速度vs即砂輪的速度、砂輪直徑deq、另還有大于零α、β、γ等參數(shù)，根據(jù)這種關系，假設所有其他條件不變，可以認為增加切割速度，將減少切削厚度的轉變。機械與材料片工作大量磨料接觸。同時，由于一些材料磨損老化，這導致了高速磨削的優(yōu)勢特點得以減少，工作表面粗糙度增加。因此，提高的砂輪速度可以增加工作的質(zhì)量，或者增加了生產(chǎn)力，這一進程取決于技術特點和對質(zhì)量要求。<

61、;/p><p>　　隨著切削速度的增加，產(chǎn)生的熱量隨之增加。增加切削速度一般不是伴隨著磨削力的比例減少而減少，從而導致磨削過程增加力的大小。 縮短研磨時間同樣是可以減少熱量的一種方式。切削率增加了必要的過程，同樣是為了實現(xiàn)這一目標，在磨料厚度增加的過程中用降低切割速度來降低超載的砂輪負荷。</p><p>　　試驗結果表明，切割速度提高了兩個要素，同時保持相同的金屬清除率可降低導致的壽命短縮，

62、但同時會導致增加過多的工作量。由于經(jīng)常在速度提高時都伴隨有增加能量的過程，每一次工作完成，隨后產(chǎn)生的總熱能都增加。當然金屬清除率提高了，同時也提高了磨削機的工作能力。熱能數(shù)量引進工作是一件和最初時的情況一樣的工作，適用于機器工作片數(shù)量雖然減少速度但保持較高的速度增長的金屬。這些因素表明，產(chǎn)量可提高機械使用高速磨削熱而不接受不良影響部分。</p><p>　　目前的高速機有如下三個方面的技術，這些是：</p&

63、gt;<p>　　1. 高速研磨機，CBN砂輪機。</p><p>　　2. 高速磨削與研磨氧化鋁車輪。</p><p>　　3. 氧化鋁研磨機床。</p><p>　　金屬清除率超比例增加，導致的生產(chǎn)力部分機械已達到每個領域的工業(yè)應用技術標準，如第五章附圖1。芯片相當于0.5至10微米厚度的一個特點是高速磨床。高速磨削大部份就是采用了這樣的應用。這項

64、技術的一個重要特點是使用時的表現(xiàn)是切削速度高。</p><p><b>　　3.高速磨削工具機</b></p><p>　　CBN高速切削阻力方面有特別的要求，需要良好阻尼特性、高硬度，也需要良好的導熱性能。這些工具通常包括一組具有很高的結構強度和薄涂層的磨料用高粘合劑附在剛體上。含有立方氮化硼作為磨料適合于高速磨削黑色物質(zhì)，因為它的硬度高和具有極好的耐磨性和耐熱性。

65、</p><p>　　首先實現(xiàn)高切割速度與金屬焊接系統(tǒng)(附圖2)。方法之一，這種系統(tǒng)是利用電鍍的方式，使機輪與生產(chǎn)單一層次的涂層材料鍍在其表面。這就構成了一個高性能的、切削速度可達到280米每秒的磨具，一直到磨料層磨損完后使用壽命才結束。</p><p>　　零件表面粗糙度對切割機磨輪也有不利的影響。粗糙度對產(chǎn)品的質(zhì)量有非常重要的影響，造成產(chǎn)品不同的形位誤差。雖然CBN切削磨輪并不算是傳統(tǒng)

66、意義上的磨削工具，結果工件表面粗糙度也可能在影響范圍內(nèi)，通過微小切削過程，這將使周邊材料的磨料涂層通過很小的步驟使切削深度減2至4微米，從而有效地減少粗糙度。</p><p>　　CBN切削磨輪包括砂輪金屬連接、樹脂連接、玻璃化連接，多層金屬高硬度連接等特有連接和穿阻力。分析這些工具，更是一個復雜的過程，但由于其結構強度高，合成樹脂的連接在允許的范圍內(nèi)具有廣泛的適應性相結合的特點，使得這些工具也需要一個標準的處理

67、化過程，玻璃化實際應用的潛力還沒有得到充分的發(fā)揮。配合適當?shù)脑O計機構，保證新發(fā)展的速度超過砂輪允許的速度范圍。相對于其他類型的連接方式，連接的玻璃化形式很容易在同時擁有高抗性。與樹脂和金屬不透水連接相比，砂輪玻璃化連接的調(diào)整可以應用于廣泛的不同制造過程和設計過程中。圖 3顯示了一個典型的微觀結構砂輪白玻璃化。</p><p>　　選擇適當?shù)牟ＡЩ拜喐咚倌ハ鞅蠕X基輪氧化更為嚴重，在這里，所含磨料金屬顆粒大小取決于

68、其具體的金屬清除率、表面粗糙度要求。直徑相當?shù)纳拜?，玻璃化實際上為突破口，圖4顯示的是含有磨料顆粒大小不同的關系，相當于直徑和金屬遷移率的具體行動外直徑的關系。然而，選擇也取決于磨料表面粗糙度的要求，粗糙度是有限制的，具體的金屬清除率也有要求。</p><p>　　除了要按照適當?shù)脑磉x擇適當機制的規(guī)定的適用問題外，組織結構，以及優(yōu)化的要求需要滿足砂輪切割速度高的特點。對于高切割速度、砂輪的常規(guī)設計和組織結構，都

69、往往導致過度延伸的引起不規(guī)則裂痕及的磨料涂層的磨損。為了消除高速機床可能出現(xiàn)的問題，工件與磨具形狀必須能配合以達到高切割速度。</p><p>　　4、高速機床的發(fā)展前景</p><p>　　高速機床所具有的優(yōu)勢是能實現(xiàn)有效調(diào)整，機床切割速度高。為了達到很高的速度，砂輪軸承運轉速度必須達到一定大小，砂輪轉動系統(tǒng)必須極度平穩(wěn)，以減少震動。因此，必須很好的固定整個機床。保持高速磨輪高的切削速度

70、，必須對磨輪進行平衡，這些技術措施，使更多的工件和產(chǎn)品質(zhì)量得到保持。</p><p>　　另一項重要因素是驅(qū)動力需要增加時，轉速變得很大。因而必須削減由PC、功耗等引起的功率：</p><p>　　其中由切割速度引起的功率：</p><p><b>　　功率損失，由：</b></p><p>　　測量圖6所示，確認了影響

71、切割速度的因素。然而，更多的能耗在空轉中。切割機的電力、PC、相對少量的速度增長，并使所有其他切割機參數(shù)保持不變。不過，這意味著需要大量的電力，適用于最大切割速度產(chǎn)生強勁的電力需要是因為轉動的砂輪、冷卻液供應以及修整砂輪。</p><p>　　制冷量和供應的壓力，砂輪清洗過程中，重點是機床設計。如圖所示，除了電力損失與換輪的損失外，砂輪與冷卻劑清洗磨輪以及供應都引起能量損失。加工的工藝參數(shù)取決于能耗，需最佳發(fā)揮高

72、速磨床的切削能力。</p><p>　　除了有效降低機器所需的電力，更要符合理想的生態(tài)環(huán)保效益，同時供應冷卻的系統(tǒng)也需要使其數(shù)量減少。各種方法都可使供應的冷卻液等自由從噴頭流通，用傳統(tǒng)的噴頭確保潤滑液流量減少，混合噴頭可保證最低數(shù)量潤滑油浪費，共同的任務是確保有足夠制冷系統(tǒng)的砂輪裝置，如圖7所示。</p><p>　　噴頭或通過砂輪供應，也可將其用于與制冷裝置接觸不多的磨輪區(qū)。體積流量大幅

73、減少，這樣才能實現(xiàn)。通過供應砂輪的噴頭設計和生產(chǎn)工藝比較復雜，需要的設備及砂輪。利用這一系統(tǒng)提供的，是一個獨立的過程中特別嚴重的現(xiàn)象。 兩種方式有減少供應砂輪的加速冷卻效果，更要有效地減少制冷劑的數(shù)量及制冷效果。供應量很小，達每小時幾毫升冷卻液。由于冷卻效果降低，以現(xiàn)代化的接觸方式將噴嘴配到專用區(qū)，。目前國內(nèi)冷卻系統(tǒng)用于高速磨輪的方式已經(jīng)審查通過。</p><p><b>　　5. 品質(zhì)因素</b

74、></p><p>　　以高速切削取代傳統(tǒng)加工等業(yè)務，高速磨削加工過程可在最短的時間完成大量零件的加工。這樣可能導致質(zhì)量受損，成為等同機晶片厚度增加。機床必須要能夠承受這樣大的力量，可以減小砂輪的工作速度。但是，迄今為止的實踐經(jīng)驗表明，并不是所有的材料在高速磨削時其機械特性都好。在極其惡劣的條件下，用耐高溫的材料，如鎳合金的基礎上，增加了工作的進程，以至于因此無法避免微觀結構破壞，但是這些材料可以更有效地利