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中國地質(zhì)大學長城學院
本科畢業(yè)設(shè)計外文資料翻譯
系 別： 工程技術(shù)系
專 業(yè)： 機械設(shè)計制造及其自動化
姓 名： 羅 飛
學 號： 05208319
2011年 12 月 28 日
外文資料翻譯譯文
鏜孔技術(shù)的發(fā)展現(xiàn)狀
1.研究意義
鏜床主要用鏜刀對工件上的預制孔進行鏜削的機床。使用不同的刀具和附件還可以進行鉆削、銑削、切螺紋及加工外圓和端面等。
通常用于加工尺寸較大，精度要求較高的孔，特別是分布在不同表面上，孔距和位置精度要求較高的孔，如箱體上的孔，還可以進行銑削，鉆孔，擴孔，鉸孔等工作。專用鏜床主要用于大批量大件生產(chǎn)，具有生產(chǎn)率高，能加工大型難加工零件，且結(jié)構(gòu)簡單，制造成本低等特點,復雜箱體零件孔系的加工,能在較為復雜的環(huán)境下工作且加工精度穩(wěn)定。
鏜削特點：刀具結(jié)構(gòu)簡單,通用性較好,可粗加工也可半精加工和精加工,適用批量較小的加工，鏜孔質(zhì)量取決于機床精度。
2.鏜床的發(fā)展歷史
? 鏜削加工通常被認為是適合在各種不同尺寸和形狀工件上加工精密孔的理想加工方式。為了適應不斷提高生產(chǎn)率的需要，鏜孔刀具的設(shè)計也在不斷創(chuàng)新改進。近年來，鏜孔刀具的技術(shù)改進主要體現(xiàn)在以下方面:
自數(shù)控(NC)技術(shù)問世以來，數(shù)字顯示技術(shù)已在CNC機床和坐標測量機上大量應用。此外，數(shù)顯千分尺、數(shù)顯卡尺等數(shù)顯量具也已得到廣泛使用。但是，數(shù)顯技術(shù)在精密鏜刀上的應用卻一直進展緩慢，其制約因素主要是鏜孔加工中使用的冷卻液和鏜頭的高速旋轉(zhuǎn)。
過去，在加工中心上進行鏜孔加工時必須非常小心，盡量避免四處飛濺的冷卻液進入鏜頭數(shù)顯裝置的電子元件中。如今，采用內(nèi)冷卻設(shè)計的新型鏜刀已能較好解決這一問題。由于冷卻液可通過刀具內(nèi)部的通道直接到達切削部位，從而實現(xiàn)了冷卻液與鏜頭數(shù)顯裝置的完全隔離。此外，新型數(shù)控鏜刀的外部進行了良好密封，可有效防止冷卻液與數(shù)顯裝置中的電子元件接觸。
在高速鏜削加工中，鏜頭的高速旋轉(zhuǎn)、離心力以及鏜頭本身的不平衡都可能引起較大振動，從而損壞靈敏的數(shù)顯裝置。新型鏜頭通過采用一種內(nèi)置平衡機構(gòu)，可以在高速鏜削時減小或消除有害的振動。目前，帶數(shù)顯讀數(shù)屏的精密鏜頭已能夠用于轉(zhuǎn)速達16000r/min的高速鏜削加工。
新型鏜頭的數(shù)字顯示屏可直接顯示出鏜刀滑塊的位移量，而不必通過調(diào)刀螺桿的轉(zhuǎn)動量來確定位移量。由于鏜桿直接安裝在鏜刀滑塊上，因此鏜頭的數(shù)顯讀數(shù)值可以真實反映出鏜刀的位移量，而不會受到螺桿空程誤差的影響。數(shù)顯鏜頭的這一特點使其可以更快速、更精密地調(diào)整鏜孔直徑，并可實現(xiàn)對加工偏差或刀具磨損的誤差補償。
大多數(shù)鏜刀都需要通過試切－測量(cut-and-measure)操作來確定其設(shè)定尺寸，即首先對一小部分被加工孔進行試切鏜削，然后測量其加工孔徑。通常，這就意味著需要將鏜刀從機床上卸下來，再安裝到一臺對刀儀上對鏜刀尺寸進行微調(diào)修正，以獲得正確的孔徑尺寸。這種預調(diào)操作之所以必要，是因為直接在機床上對普通鏜頭的游標刻度盤進行讀數(shù)和預調(diào)相當困難，但是，這種操作方式可能造成鏜孔尺寸超差或損壞工件。
由于在機床上安裝鏜刀時難以預測其刀尖偏差，因此需要采用試切－測量操作來預調(diào)刀具。如果采用易于讀數(shù)的新型數(shù)顯鏜刀，則可能實現(xiàn)直接在機床主軸上對刀具鏜孔直徑進行微調(diào)，其尺寸調(diào)整范圍可達0.0001〃(0.00254mm)。即使因為機床主軸的進刀限制，必須將鏜刀從機床上卸下來進行孔徑尺寸調(diào)整，新型數(shù)顯鏜刀的調(diào)刀過程也更快速、更精確。
3.鏜床的發(fā)展方向及其特點
現(xiàn)代鏜床由過去的專用鏜床發(fā)展為今天的通用性機床，具有較大的工藝范圍，且運動靈活，柔性高，能加工復雜的零件，通用鏜床正向數(shù)控化、大型化、超精密、高速度等方向發(fā)展。一些專用鏜床向標準化發(fā)展，使專用鏜床生產(chǎn)周期大為降低，生產(chǎn)成本降低，體積更小，能滿足各種加工要求。
在鏜床上鏜孔時，鏜刀基本與車刀相同，不同之處是工件不動，鏜刀在旋轉(zhuǎn)。鏜孔加工精度一般為IT9—IT7，表面粗糙度為Ra6.3—0.8mm。
4.加工中心上鏜孔加工的特點
4.1刀具轉(zhuǎn)動
和車床加工不同，加工中心加工時由于刀具轉(zhuǎn)動，便不可能在加工中及時掌握刀尖的情況來調(diào)節(jié)進刀量等。也不可能像數(shù)控車床那樣可以只調(diào)節(jié)數(shù)控按扭就可以改變加工直徑。這便成了完全自動化加工的一個很大的障礙。也正因為這樣所以就要求鏜刀必須具有微調(diào)機構(gòu)或自動補償機能，特別是在精鏜時根據(jù)公差要求有時必須在微米級調(diào)節(jié)。另外，加工中心鏜孔時由于切屑的流出方向在不斷地改變，所以刀尖、工件的冷卻以及切屑的排出都要比車床加工時難的多。
4.2刀具的顛振
鏜孔加工時最常出現(xiàn)的、也是最令人頭疼問題是顛振。在加工中心上發(fā)生顛振的原因主要有以下幾點：
1)工具系統(tǒng)的剛性：包括刀柄、鏜桿、以及中間連接部分的剛性。因為是懸臂加工所以特別是小孔、深孔及硬質(zhì)工件的加工時，工具系統(tǒng)的剛性尤為重要。
2)刀具系統(tǒng)的動平衡：相對于刀具系統(tǒng)的轉(zhuǎn)動軸心，刀具自身如有一不平衡質(zhì)量，在轉(zhuǎn)動時因不平衡的離心力的作用而導致顛振的發(fā)生。特別是在高速加工時刀具的動平衡性所產(chǎn)生影響很大。
3)工件自身或工件的固定剛性：像一些較小、較薄的部件由于其自身的剛性不足，或由于工件形狀等原因無法使用合理的夾具進行充分的固定。
4)刀片的刀尖形狀：刀片的前角、刀尖半徑、斷屑槽形狀的不同所產(chǎn)生的切削抗力也不同。
5)切削條件：包括切削速度、進給量、進刀量以及給切削油方式及種類等。
6)機器的主軸系統(tǒng)：機器主軸自身的剛性、軸承及齒輪的性能以及主軸和刀柄之間的連接剛性。
4.3刀具的裝夾
在鏜削孔時，最重要的是在加工中心上正確裝夾刀具。在小孔鏜削中，刀具的中心高是導致刀具失效的重要因素。如果刀具安裝低于中心高，將影響刀具的加工性能。主要表現(xiàn)在：
1)切削刃相對于工件的主后角減小，導致刀具的后刀面與工件接觸，使刀片與工件之間發(fā)生摩擦，當?shù)镀D(zhuǎn)時，這種摩擦進一步會使刀尖發(fā)生偏離，導致刀具更深地切入工件。切削刃的幾何參數(shù)對切削效率的高低和加工質(zhì)量的好壞有很大影響。增大前角，可減小前刀面擠壓切削層時的塑性變形，減小切屑流經(jīng)前面的摩擦阻力，從而減小切削力和切削熱。但增大前角，同時會降低切削刃的強度，減小刀頭的散熱體積。
2)當?shù)毒吆蠼菧p小時，刀片相對于工件的前角也增大，從而引起刀具刮削工件，引起刀具振動并損壞刀具。這種情況在鏜削小孔時更為嚴重。為此建議刀具安裝應略高于中心高(但應盡可能接近中心高)。這樣可使刀具相對于工件的法向后角增大，切削條件得到改善，如果加工時產(chǎn)生振動，刀尖會向下和向中心偏斜，從而接近理想的中心高。刀具也可輕微地退出，減小削傷工件的可能性。此外，刀具前角也將減小，這樣可穩(wěn)定工作壓力。如果前角減小到0°，就會產(chǎn)生太大的工作壓力，導致刀具失效。所以在鏜孔時，應選取正前角的鏜刀，在鏜1mm的小孔時，鏜桿的直徑只有0.75mm左右，使刀具承受的切削力減小。
4.4切屑的排出
在鏜削孔時，切屑的有效排出至關(guān)重要。加工時，由于刀具在孔內(nèi)，切削液很難到達切削刃，造成切屑排出困難，影響刀具壽命。為解決這一難題，一些刀具制造商開發(fā)出一種沿切削刃帶冷卻槽的刀片，使切削液直接流向切削刃，防止切屑堵塞和刀具損壞。
外文原文
Single-boring technology development status
Machine is a metal blanks processed into machine parts machine, which is to create the machine the machine, it is also known as "working mother ship" or "machine tool", customarily referred to as machine tools. Modern Machinery Manufacturing in the processing of mechanical parts many ways, in addition to cutting, there are casting, forging, welding, stamping, extrusion, etc., but the Fan Shu high precision and surface roughness require smaller parts, are generally required to machine tool with the cutting method for final processing. In the general machine manufacturing, machine tools accounted for by the work of the machine responsible for the processing workload of the total production 40% to 60%, machine building of a modern national economy plays a significant role.
1. Research significance
Boring machine is mainly used on the boring tool on the workpiece to conduct pre-hole boring machine tool. Using different tools and accessories can also be carried out drilling, milling, thread cutting and processing of cylindrical and face and so on.
Commonly used in machining large size, high precision holes, especially located in different surface, the pitch and location of the holes require a higher precision, such as the holes on the box, but also can be milling, drilling, expanding hole, reaming and so on. Special boring machine is mainly used for large volume production, with high productivity, can be difficult to process large-scale processing of parts, and the simple structure and low manufacturing costs, complexity, holes box parts processing, can be more complex environment to work and processing precision and stability.
Boring features:Tool structure is simple, universal good, can be roughing can also be semi-finishing and finishing, for small batch processing, the quality depends on the boring machine accuracy.
2. Boring history of development of
Metal cutting machine throughout this occupies a very heavy position, accounting for the total workload of machine 40% ~ ~ 60%. In 1770, before and after, due to hand and general metalworking machinery can not reach precision machining cylinder steam engine, people will create a special processing of the steam engine cylinder hole of professional machines, so was born the first horizontal boring machine.
As the manufacture of weapons needs, water appeared in the 15th century power-driven barrel boring machine. 1774, British J. Wilkinson invented barrel boring machine, cylinder steam engine for processing the following year. Around 1880, Germany began producing belt around the columns and the table horizontal boring machine. The early 20th century, due to watch the development of equipment manufacturing industry needs to pitch high precision machining equipment, made in Switzerland in 1905, center coordinates of a small desktop machine. In 1917, in the United States made a single cylindrical coordinates boring. In 1920 the Swiss made double-column coordinate boring machine. At that time the vast majority of precision jig borer with screw nut, standard measuring rod (or gauge blocks) and the dial gauge as a coordinate positioning device, the coordinate positioning accuracy of only 6 to 10 microns. To meet the large, special heavy workpieces, the 20th century, 30 years developed a BORING MACHINE 30 years, in Germany, and Switzerland have emerged in order to line scale optical positioning jig borer, coordinate positioning accuracy to 2 to 6 microns. With the milling the increased workload in the 20th century appeared in 50's floor boring and milling machine. 60 years later, with the development of electronic technology, coordinate boring machine to a digital display and digital control direction, using grating, sensor synchronizer, laser interferometer and magnetic gate, etc., as coordinate positioning device, and some additional automatic tool change device . Since then, with the scientific and technological development, constantly improve the performance of boring, but also appeared in succession in processing a variety of large and complex parts of the coordinates of boring. Processing of parts due to the ever-changing, promoting the continuous development and improvement of the boring machine. Finally developed into a universal, years of horizontal boring machine. For the heavy manufacturing, those bulky, heavy tonnage hole machining of large workpieces, due to difficulties in clamping the workpiece movement and can not be processed in the general horizontal boring mills, therefore, in the horizontal boring machine manufacturers have developed on the basis of the Heavy BORING MACHINE.
3. Modern boring machine status and level of development
Modern machines toward high speed, high efficiency, high precision was sent to development, increasingly demanding high-precision mechanical parts, while institutions are becoming increasingly complicated, especially in multi-box components with the holes have their own characteristics in addition to its dimensional accuracy requirements, , as well as the shape precision and the location of the holes between the accuracy requirements. Boring in these processing by the most important.
Hyundai has also been some strong flexible production capacity dedicated boring machine is not high. If using a large mass connecting rod bearing, piston bore, pump casing and other components on the special processing of precision hole boring machine King Kong.
The rapid development of modern Boring There are about several forms:
1) Horizontal Boring Machine: mainly used for side-hole processing.
2) Coordinate boring machine: a high-precision machine tools. Main features: with the coordinates of precision measuring devices.
3) Diamond Boring: A high-speed precision boring machine. Main features: vc very high, ap, and f is very small, machining accuracy is up to IT5 - IT6.Ra up to 0.63 - 0.08μm.
4) special boring: Private boring milling head. Main features: simple structure, low manufacturing costs, can adapt to rapid production and complex production environment.
Which coordinates the development by the boring machine for the rapid, generally single-column sub-jig borer, double column and horizontal 3 types.
Single Column jig borer: spindle vertical arrangement, driven by the spindle sleeve to move up or down in order to achieve the vertical feed, and some spindle box can be moved up and down along the column in order to adapt to different rail height of the workpiece. Table for longitudinal movement along the slide, slide along the bed rail for horizontal movement, to meet the positioning coordinates. Table 3 side open, easy to operate. Most small and medium sized jig borer layout using this form, coordinate positioning accuracy of 2 to 4 microns.
Double-Column jig borer: 2 column through the top of the upper beam connections, beam can be adjusted up and down along the column position of rail. Spindle box rails for lateral movement along the beams, workstations along the rail bed for vertical movement, to meet the positioning coordinates. A large double-column coordinates of the column on the boring machine comes with the level of spindle box. Use of double-column frame structure, high stiffness, medium and large multi-boring machine coordinates for this form of the coordinate positioning accuracy of 3 to 10 microns.
A single column and double columns coordinate boring machine spindle is perpendicular to the work table, the general direction for machining a hole in the workpiece, such as jigs, dies and templates so boring. Processing in several directions of the workpiece has a hole should be used for universal rotary table, so the workpiece size and weight are restricted.
Horizontal jig borer: two coordinate direction, respectively, table movement lateral movement and spindle box vertical movement. Rotary table in the horizontal plane. Feed motion from the vertical slide of the axial movement or spindle sleeve stretch to achieve. As the spindle parallel to the work table, using a precision rotary table can be easily installed after the workpiece machining box-type parts around the coordinates of all holes, and the workpiece easy installation, high production efficiency. This boring machine is suitable box-type parts processing.
Modern boring machine from the previous development of special boring machine for today's versatile, with a large range of craft, and sports a flexible, flexible high, can machine complex parts, universal CNC boring machine forward and large-scale, ultra-precision, high-speed other direction. Some special boring machine to the standardization of development, so that special boring machine greatly reduced production cycle, production costs, smaller, can meet a variety of processing requirements.
When the Boring Machine Boring, Boring Tool knife basically the same, only difference is that the workpiece does not move, boring rotating knife. Boring accuracy is generally IT9-IT7, the surface roughness is Ra6.3-0.8mm.
4. Machining Center Boring characteristics
4.1 Tool rotation
?? ??And the lathe is different from machining center machining due to tool rotation, it is impossible to grasp the tip in the processing of cases in a timely manner to adjust the feed consumption level. Can not be done, like CNC lathes can only adjust button on the CNC machining diameter can be changed. This has become a fully automated processing of a large obstacle. It is because of this reason that requires boring tool must have a body or fine-tuning automatic compensation function, especially in the boring at times when the tolerance requirements under the micro-level must be adjusted. In addition, the processing center boring holes due to the outflow direction of chip constantly changing, so tip, workpiece and chip cooling of the exhaust must be more than difficult for the multi-lathe.
4.2 tool vibration Britain
Boring most often occurs, and it is the most headache problem is that Britain vibration. Britain occurred in the processing center vibration because of the following points:
??? ??1) tool rigidity of the system include: Holder, Boring Bar, as well as the middle part of the rigid link. Cantilever process because it is so, especially with holes, deep hole and rigid workpieces, the tool system rigidity is particularly important.
????? 2) Tool Balancing System: the system relative to the tool axis of rotation, the tool itself, if an imbalance in the quality of the rotation due to imbalance in the role of the centrifugal force caused by the occurrence of vibration Britain. Especially in the high-speed machining tool produced by dynamic balancing of a significant influence.
3) The workpiece itself or the fixed workpiece rigidity: Like a number of smaller, thinner parts because of its rigidity is insufficient, or other reasons due to workpiece shape of the fixture can not be adequate to use reasonable fixed.
????? 4) The blade tip shape: the first blade angle, tip radius, chip-breaker generated by the different shape of the cutting resistance is also different.
???? ?5) Cutting conditions: including cutting speed, feed rate, feed volume, and to the cutting oil ways and forms.
???? 6) The machine spindle system: the rigidity of the machine spindle itself, bearing and gear performance, and the connection between the spindle and shank rigidity.
4.3 Tool Clamping
????In boring holes, the most important thing is setup correctly on the machining center tool. In the small hole boring, the tool center height is an important factor leading to tool failure. If the tool installed below the center height, this will affect the processing performance of cutting tools. Following main features:
1) The cutting edge relative to the workpiece main horn decreases, leading to the tool flank contact with the workpiece, so that the friction between the blade and the workpiece, when the blades rotate, this would further tip the friction deviation occurs, leading to Tool deeper cut into the workpiece. The geometric parameters on the cutting edge level of cutting efficiency and processing quality is good or bad has a great influence. Increase rake angle, the rake face can be reduced cutting layer extruded plastic deformation, reducing the flow through the chip in front of friction, thereby reducing the cutting force and cutting heat. However, increased anterior horn at the same time will reduce the strength of cutting edge, reduce the heat Segment size.
2) When the cutting tool angle decreases, the blade angle relative to the workpiece is also the first increase, which led to the workpiece shaving tool, tool vibration and damage caused by knives. This situation is more serious when the boring hole. Therefore recommended that installation tool should be slightly higher than the center (but shall be as close to the center high). This will enable the tool of law relative to the workpiece back angle increases, cutting conditions have been improved, if the machining vibration, tip downwards and to the center deflection, thus close to the ideal center height. Tool can also be slightly out, reducing the possibility of the workpiece cut injury. In addition, the tool will also be reduced before the corner, there could be a stable work pressure. If the front is reduced to 0 °, it will have much work pressure, leading to tool failure. So boring, they should select the positive rake angle of the boring tool, in the 1mm hole boring, the boring bar is only 0.75mm in diameter around the tool to withstand the cutting force decreases.
4.4 Chip discharges
????In boring holes, chip critical to the effective discharge. Processing, due to tool in the hole, cutting fluid is difficult to reach the cutting edge, resulting in difficulties in chip discharge, affecting tool life. To address this problem, some manufacturers have developed a cutting tool along the cutting edge of the blade with a cooling tank, so that direct the flow of cutting fluid cutting edge, to prevent chip clogging and tool damage.