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1、<p> High-speed machining and demand for the development </p><p> High-speed machining is contemporary advanced manufacturing technology an important component of the high-efficiency, High-precision a
2、nd high surface quality, and other features. This article presents the technical definition of the current state of development of China''s application fields and the demand situation. </p><p> High
3、-speed machining is oriented to the 21st century a new high-tech, high-efficiency, High-precision and high surface quality as a basic feature, in the automobile industry, aerospace, Die Manufacturing and instrumentation
4、industries gained increasingly widespread application, and has made significant technical and economic benefits. contemporary advanced manufacturing technology an important component part.</p><p> HSC is to
5、 achieve high efficiency of the core technology manufacturers, intensive processes and equipment packaged so that it has a high production efficiency. It can be said that the high-speed machining is an increase in the qu
6、antity of equipment significantly improve processing efficiency essential to the technology. High-speed machining is the major advantages : improve production efficiency, improve accuracy and reduce the processing of cut
7、ting resistance.</p><p> The high-speed machining of meaning, at present there is no uniform understanding, there are generally several points as follows : high cutting speed. usually faster than that of th
8、eir normal cutting 5 -10 times; machine tool spindle speed high, generally spindle speed in -20000r/min above 10,000 for high-speed cutting; Feed at high velocity, usually 15 -50m/min up to 90m/min; For different cutting
9、 materials and the wiring used the tool material, high-speed cutting the meaning is not necessarily</p><p> High-speed machining of machine tools, knives and cutting process, and other aspects specific requ
10、irements. Several were from the following aspects : high-speed machining technology development status and trends.</p><p> At this stage, in order to achieve high-speed machining, general wiring with high f
11、lexibility of high-speed CNC machine tools, machining centers, By using a dedicated high-speed milling, drilling. These equipment in common is : We must also have h igh-speed and high-speed spindle system feeding system,
12、 Cutting can be achieved in high-speed process. High-speed cutting with the traditional cutting the biggest difference is that "Machine-tool-workpiece" the dynamic characteristics of cutting perfor</p>&
13、lt;p> In the high-speed cutting, material removal rate (Metal Removal Rate, MRR), unit time that the material was removed volume, usually based on the "machine-tool-workpiece" whether Processing System &quo
14、t;chatter." Therefore, in order to satisfy the high-speed machining needs, we must first improve the static and dynamic stiffness of machine spindle is particularly the stiffness characteristics. HSC reason at this
15、stage to be successful, a very crucial factor is the dynamic characteristics of the master</p><p> In order to better describe the machine spindle stiffness characteristics of the project presented new dime
16、nsionless parameter - DN value, used for the evaluation of the machine tool spindle structure on the high-speed machining of adaptability. DN value of the so-called "axis diameter per minute speed with the product.&
17、quot; The newly developed spindle machining center DN values have been great over one million. To reduce the weight bearing, but also with an array of steel products than to the much </p><p> Feed the machi
18、ne sector, high-speed machining used in the feed drive is usually larger lead, multiple high-speed ball screw and ball array of small-diameter silicon nitride (Si3N4) ceramic ball, to reduce its centrifugal and gyroscopi
19、c torque; By using hollow-cooling technology to reduce operating at high speed ball screw as temperature generated by the friction between the lead screw and thermal deformation.</p><p> In recent years, th
20、e use of linear motor-driven high-speed system of up to'''' Such feed system has removed the motor from workstations to Slide in the middle of all mechanical transmission links, Implementation of Machine
21、Tool Feed System of zero transmission. Because no linear motor rotating components, from the role of centrifugal force, can greatly increase the feed rate. Linear Motor Another major advantage of the trip is unrestricted
22、. The linear motor is a very time for a continuous machin</p><p> 2002 world-renowned Shanghai Pudong maglev train project of maglev track steel processing, Using the Shenyang Machine Tool Group Holdings Li
23、mited McNair friendship company production plants into extra-long high-speed system for large-scale processing centers achieve . The machine feeding system for the linear guide and rack gear drive, the largest table feed
24、 rate of 60 m / min, Quick trip of 100 m / min, 2 g acceleration, maximum speed spindle 20000 r / min, the main motor power 80 kW. X-axis di</p><p> In addition, the campaign machine performance will also d
25、irectly affect the processing efficiency and accuracy of processing. Mold and the free surface of high-speed machining, the main wiring with small cut deep into methods for processing. Machine requirements in the feed ra
26、te conditions, should have high-precision positioning functions and high-precision interpolation function, especially high-precision arc interpolation. Arc processing is to adopt legislation or thread milling cutter mold
27、 or</p><p> Cutting Tools Tool Material development </p><p> high-speed cutting and technological development of the history, tool material is continuous progress of history. The representatio
28、n of high-speed cutting tool material is cubic boron nitride (CBN). Face Milling Cutter use of CBN, its cutting speed can be as high as 5000 m / min, mainly for the gray cast iron machining. Polycrystalline diamond (PCD)
29、 has been described as a tool of the 21st century tool, It is particularly applicable to the cutting aluminum alloy containing silica material, which</p><p> Tool Coating : CBN and diamond cutter, despite g
30、ood high-speed performance, but the cost is relatively high. Using the coating technology to make cutting tool is the low price, with excellent mechanical properties, which can effectively reduce the cost. Now high-speed
31、 processing of milling cutter, with most of the wiring between the Ti-A1-N composite technology for the way of multi-processing, If present in the non-ferrous metal or alloy material dry cutting, DLC (Diamond Like Carbon
32、) coating on</p><p> Tool clamping system : Tool clamping system to support high-speed cutting is an important technology, Currently the most w idely used is a two-faced tool clamping system. Has been forma
33、lly invested as a commodity market at the same clamping tool system are : HSK, KM, Bigplus. NC5, AHO systems. </p><p> In the high-speed machining, tool and fixture rotary performance of the balance not onl
34、y affects the precision machining and tool life. it will also affect the life of machine tools. So, the choice of tool system, it should be a balanced selection of good products. Process ParametersCutting speed of high-s
35、peed processing of conventional shear velocity of about 10 times. For every tooth cutter feed rate remained basically unchanged, to guarantee parts machining precision, surface quality and dura</p><p> To a
36、dapt to the needs of new models, auto body panel molds and resin-prevention block the forming die. must shorten the production cycle and reduce the cost of production and, therefore, we must make great efforts to promote
37、 the production of high-speed die in the process. SAIC affiliated with the company that : Compared to the past, finishing, further precision; the same time, the surface roughness must be met, the bending of precision, th
38、is should be subject to appropriate intensive manual pro</p><p> To play for machining centers and boring and milling machining center category represented by the high-speed machining technology and automat
39、ic tool change function of distinctions Potential to improve processing efficiency, the processing of complex parts used to be concentrated as much as possible the wiring process, that is a fixture in achieving multiple
40、processes centralized processing and dilute the traditional cars, milling, boring, Thread processing different cutting the limits of techno</p><p> HSC has a lot of advantages such as : a large number of ma
41、terials required resection of the workpiece with ultrafine, thin structure of the workpiece, Traditionally, the need to spend very long hours for processing mobile workpiece and the design of rapid change, short product
42、life cycle of the workpiece, able to demonstrate high-speed cutting brought advantages. </p><p> 高速切削加工的發(fā)展及需求</p><p> 高速切削加工是當(dāng)代先進(jìn)制造技術(shù)的重要組成部分,擁有高效率、高精度及高表面質(zhì)量等特征。本文介紹此技術(shù)的定義、發(fā)展現(xiàn)狀、適用領(lǐng)域以及中國的需求情況。&l
43、t;/p><p> 高速切削加工是面向21世紀(jì)的一項(xiàng)高新技術(shù),它以高效率、高精度和高表面質(zhì)量為基本特征,在汽車工業(yè)、航空航天、模具制造和儀器儀表等行業(yè)中獲得了愈來愈廣泛的應(yīng)用,并已取得了重大的技術(shù)經(jīng)濟(jì)效益,是當(dāng)代先進(jìn)制造技術(shù)的重要組成部分。</p><p> 高速切削是實(shí)現(xiàn)高效率制造的核心技術(shù),工序的集約化和設(shè)備的通用化使之具有很高的生產(chǎn)效率。可以說,高速切削加工是一種不增加設(shè)備數(shù)量而大幅
44、度提高加工效率所必不可少的技術(shù)。高速切削加工的優(yōu)點(diǎn)主要在于:提高生產(chǎn)效率、提高加工精度及降低切削阻力。 </p><p> 有關(guān)高速切削加工的含義,目前尚無統(tǒng)一的認(rèn)識,通常有如下幾種觀點(diǎn):切削速度很高,通常認(rèn)為其速度超過普通切削的5-10倍;機(jī)床主軸轉(zhuǎn)速很高,一般將主軸轉(zhuǎn)速在10000-20000r/min以上定為高速切削;進(jìn)給速度很高,通常達(dá)15-50m/min,最高可達(dá)90m/min;對于不同的切削材料和所
45、釆用的刀具材料,高速切削的含義也不盡相同;切削過程中,刀刃的通過頻率(Tooth Passing Frequency)接近于“機(jī)床-刀具-工件”系統(tǒng)的主導(dǎo)自然頻率(Dominant Natural Frequency)時(shí),可認(rèn)為是高速切削??梢姼咚偾邢骷庸な且粋€綜合的概念。</p><p> 1992年,德國Darmstadt工業(yè)大學(xué)的H. Schulz教授在CIRP上提出了高速切削加工的概念及其涵蓋的范圍,如
46、圖1所示。認(rèn)為對于不同的切削對象,圖中所示的過渡區(qū)(Transition)即為通常所謂的高速切削範(fàn)圍,這也是當(dāng)時(shí)金屬切削工藝相關(guān)的技術(shù)人員所期待或者可望實(shí)現(xiàn)的切削速度。</p><p> 高速切削加工對機(jī)床、刀具和切削工藝等方面都有一些具體的要求。下面分別從這幾個方面闡述高速切削加工技術(shù)的發(fā)展現(xiàn)狀和趨勢。</p><p> 現(xiàn)階段,為了實(shí)現(xiàn)高速切削加工,一般釆用高柔性的高速數(shù)控機(jī)床、加
47、工中心,也有釆用專用的高速銑、鉆床。這些設(shè)備的共同之處是:必須同時(shí)具有高速主軸系統(tǒng)和高速進(jìn)給系統(tǒng),才能實(shí)現(xiàn)材料切削過程的高速化。高速切削與傳統(tǒng)切削最大的區(qū)別是,“機(jī)床-刀具-工件”系統(tǒng)的動態(tài)特性對切削性能有更強(qiáng)的影響力。在該系統(tǒng)中,機(jī)床主軸的剛度、刀柄形式、刀長設(shè)定、主軸拉刀力、刀具扭力設(shè)定等,都是影響高速切削性能的重要因素。 </p><p> 在高速切削中,材料去除率(Metal Removal Rate,
48、MRR),即單位時(shí)間內(nèi)材料被切除的體積,通常受限于“機(jī)床-刀具-工件”工藝系統(tǒng)是否出現(xiàn)“顫振”。因此,為了滿足高速切削加工的需求,首先要提高機(jī)床動靜剛度尤其是主軸的剛度特性。現(xiàn)階段高速切削之所以能夠成功,一個很關(guān)鍵的因素在于對系統(tǒng)動態(tài)特性問題的掌握和處理能力。</p><p> 為了更好地描述機(jī)床主軸的剛度特性,工程上提出新的無量綱參數(shù)—DN值,用以評價(jià)機(jī)床的主軸結(jié)構(gòu)對高速切削加工的適應(yīng)性。所謂DN值即“主軸直
49、徑與每分鐘轉(zhuǎn)速之積”。新近開發(fā)的加工中心主軸DN值大都已超過100萬。為了減輕軸承的重量,還釆用了比鋼制品要輕得多的陶瓷球軸承;軸承潤滑方式大都釆用油氣混合潤滑方式。在高速切削加工領(lǐng)域,目前已開發(fā)空氣軸承和磁軸承以及由磁軸承和空氣軸承合并構(gòu)成的磁氣/空氣混合主軸。 </p><p> 在機(jī)床進(jìn)給機(jī)構(gòu)方面,高速切削加工所用的進(jìn)給驅(qū)動機(jī)構(gòu)通常都為大導(dǎo)程、多頭高速滾珠絲槓,滾珠釆用小直徑氮化硅(Si3N4)陶瓷球,以
50、減少其離心力和陀螺力矩;釆用空心強(qiáng)冷技術(shù)來減少高速滾珠絲槓運(yùn)轉(zhuǎn)時(shí)由于摩擦產(chǎn)生溫升而造成的絲槓熱變形。</p><p> 近幾年來,用直線電機(jī)驅(qū)動的高速進(jìn)給系統(tǒng)問世,這種進(jìn)給方式取消了從電動機(jī)到工作臺溜板之間的一切中間機(jī)械傳動環(huán)節(jié),實(shí)現(xiàn)了機(jī)床進(jìn)給系統(tǒng)的零傳動。由于直線電機(jī)沒有任何旋轉(zhuǎn)元件,不受離心力的作用,可以大大提高進(jìn)給速度。直線電機(jī)的另一大優(yōu)點(diǎn)是行程不受限制。直線電機(jī)的次極是一段一段連續(xù)鋪在機(jī)床的床身上。次極
51、鋪到哪里,初極工作臺就可運(yùn)動到哪里,而且對整個進(jìn)給系統(tǒng)的剛度沒有任何影響。釆用高速絲槓或直線電機(jī),能夠大大提高機(jī)床進(jìn)給系統(tǒng)的快速響應(yīng)。直線電機(jī)最高加速度可達(dá)2-10G(G為重力加速度),最大進(jìn)給速度可達(dá)60-200m/min或更高。</p><p> 2002年舉世矚目的上海浦東磁懸浮列車工程中的磁浮軌道鋼梁加工,釆用沈陽機(jī)床控股有限公司集團(tuán)中捷友誼公司廠生產(chǎn)的超長進(jìn)給系統(tǒng)高速大型加工中心實(shí)現(xiàn)。該機(jī)床的進(jìn)給系統(tǒng)
52、為直線導(dǎo)軌和齒輪齒條傳動,工作臺最大進(jìn)給速度60m/min,快速行程100m/min,加速度2g,主軸最高轉(zhuǎn)速20000r/min,主電機(jī)功率80kW。其X軸的行程長達(dá)30m,切削25m長的磁浮軌道鋼梁誤差小于0.15mm,為磁懸浮列車工程的順利竣工提供了有力的技術(shù)保證。</p><p> 此外,機(jī)床的運(yùn)動性能也將直接影響加工效率和加工精度。在模具及自由曲面的高速切削加工中,主要釆用小切深大進(jìn)給的加工方法。要求
53、機(jī)床在大進(jìn)給速度條件下,應(yīng)具有高精度定位功能和高精度插補(bǔ)功能,特別是圓弧高精度插補(bǔ)。圓弧加工是釆用立銑 刀或螺紋刀具加工零部件或模具時(shí),必不可少的加工方法。</p><p> 刀具材料的發(fā)展:高速切削技術(shù)發(fā)展的歷史,也就是刀具材料不斷進(jìn)步的歷史。高速切削的代表性刀具材料是立方氮化硼(CBN)。端面銑削使用CBN刀具時(shí),其切削速度可高達(dá)5000m/min,主要用于灰口鑄鐵的切削加工。聚晶金剛石(PCD)刀具被稱
54、之為21世紀(jì)的刀具,它特別適用于切削含有SiO2的鋁合金材料,而這種金屬材料重量輕、強(qiáng)度高,廣泛地應(yīng)用于汽車、摩托車發(fā)動機(jī)、電子裝置的殼體、底座等方面。目前,用聚晶金剛石刀具端面銑削鋁合金時(shí),5000m/min的切削速度已達(dá)到實(shí)用化水平,此外陶瓷刀具也適用于灰口鑄鐵的高速切削加工。</p><p> 涂層刀具:CBN和金剛石刀具盡管具有很好的高速切削性能,但成本相對較高。釆用涂層技術(shù)能夠使切削刀具既價(jià)格低廉,又
55、具有優(yōu)異性能,可有效降低加工成本?,F(xiàn)在高速加工用的立銑刀,大都釆用TiAIN系的復(fù)合多層涂鍍技術(shù)進(jìn)行處理,如目前在對鋁合金或有色金屬材料進(jìn)行干式切削時(shí),DLC(Diamond Like Carbon)涂層刀具就受到極大的關(guān)注,預(yù)計(jì)其巿場前景十分可觀。</p><p> 刀具夾持系統(tǒng):刀具的夾持系統(tǒng)是支撐高速切削的重要技術(shù),目前使用最為廣泛的是兩面夾緊式工具系統(tǒng)。已作為商品正式投放巿場的兩面夾緊式工具系統(tǒng)主要有:
56、HSK、KM、Bigplus、NC5、AHO等系統(tǒng)。 </p><p> 在高速切削的情況下,刀具與夾具回轉(zhuǎn)平衡性能的優(yōu)劣,不僅影響加工精度和刀具壽命,而且也會影響機(jī)床的使用壽命。因此,在選擇工具系統(tǒng)時(shí),應(yīng)盡量選用平衡性能良好的產(chǎn)品。</p><p> 高速加工的切削速度為常規(guī)切速的10倍左右。為了使刀具每齒進(jìn)給量基本保持不變,以保證零件的加工精度、表面質(zhì)量和刀具的耐用度,則進(jìn)給量也必
57、須相應(yīng)提高10倍左右,達(dá)到60m/min以上,有的甚至高達(dá)120m/min。因此,高速切削加工通常是釆用高轉(zhuǎn)速、大進(jìn)給和小切深的切削工藝參數(shù)。由于高速切削的切削余量往往很小,所形成的切屑很薄很輕,把切削時(shí)產(chǎn)生的熱量很快帶走;若釆用全新耐熱性更好的刀具材料和涂層,釆用干切削工藝也是高速切削加工的理想工藝方案。</p><p> 用高速加工中心組成高效率的柔性生產(chǎn)線(FTL或FML),具有小型化、柔性突出以及易于變
58、更加工內(nèi)容等顯著特點(diǎn)。圖2為上汽集團(tuán)某發(fā)動機(jī)公司利用該生產(chǎn)線加工發(fā)動機(jī)機(jī)體、汽缸蓋、濾清器座等工件的實(shí)例。</p><p> 為了盡快適應(yīng)新車型的需要,汽車車身覆蓋件模具和樹脂防沖擋的成形模具等,均必須縮短制作周期和降低生產(chǎn)成本,因此,必須下大力推進(jìn)模具生產(chǎn)高速化的進(jìn)程。上汽集團(tuán)所屬各公司認(rèn)為:與過去的精加工相比,進(jìn)一步實(shí)現(xiàn)高精度化;同時(shí)必須滿足表面粗糙度、彎曲度的精度要求,為此應(yīng)施以適當(dāng)?shù)氖止ぞ藜庸?,由于?/p>
59、削速度的極大提高,與過去的精加工工序相比,加工周期應(yīng)大幅度縮短。</p><p> 為了發(fā)揮以車削加工中心和鏜銑類加工中心為代表的高速切削加工技術(shù)和自動換刀功能的優(yōu)勢,提高加工效率,對復(fù)雜零件的加工應(yīng)盡可能釆用集中工序的原則,即要求在一次裝夾中實(shí)現(xiàn)多道工序的集中加工,淡化傳統(tǒng)的車、銑、鏜、螺紋加工等不同切削工藝的界限,充分發(fā)揮設(shè)備和刀具的高速切削功能,是當(dāng)前提高數(shù)控機(jī)床效率、加快產(chǎn)品開發(fā)的有效途徑。為此,對刀具
60、提出了多功能的新要求,要求一種刀具能完成零件不同工序的加工,減少換刀次數(shù),節(jié)省換刀時(shí)間,以減少刀具的數(shù)量和庫存量,有利于管理和降低制造成本。較常用的有多功能車刀、銑刀、鏜銑刀、鉆銑刀、鉆-銑螺紋-倒角等刀具。與此同時(shí),在批量生產(chǎn)線上,使用針對工藝需要開發(fā)的專用刀具、復(fù)合刀具或智能刀具,可以提高加工效率和精度,減少投資。在高速切削條件下,有的專用刀具可將零件的加工時(shí)間降至原來的1/10以下,效果十分顯著。</p><p
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