镗孔技术的发展现状机械课程毕业设计外文文献翻译@中英文翻译@外文翻译

中国地质大学长城学院 本科毕业设计外文资料翻译 系 别： 工程技术系 专 业： 机械设计制造及其自动化 姓 名： 宋楠 学 号： 05211612 2015年 4 月 28 日 外文资料翻译译文 镗孔技术的发展现状 1.研究意义 镗床主要用镗刀对 工件 上的预制 孔进行镗削的 机床 。使用不同的 刀具 和附件还可以进行钻削、铣削、切 螺纹 及加工外圆和端面等。 通常用于加工尺寸较大，精度要求较高的孔，特别是分布在不同表面上，孔距和位置精度要求较高的孔 ， 如箱体上的孔，还可以进行铣削，钻孔，扩 孔，铰孔等工作。专用镗床主要用于大批量大件生产，具有生产率高，能加工大型难加工零件，且结构简单，制造成本低等特点 ,复杂箱体零件孔系的加工 ,能在较为复杂的环境下工作且加工精度稳定。 镗削特点 ： 刀具结构简单 ,通用性 较好 ,可粗加工也可半精加工和精加工 ,适用批量较小的加工，镗孔质量取决于机床精度 。 2.镗床的发展 历史 镗削加工通常被认为是适合在各种不同尺寸和形状工件上加工精密孔的理想加工方式 。为了适应不断提高生产率的需要，镗孔刀具的设计也在不断创新改进。近年来，镗孔刀具的技术改进主要体现在以下方面 : 自数 控 (NC)技术问世以来，数字显示技术已在 CNC 机床和坐标测量机上大量应用。此外，数显千分尺、数显卡尺等数显量具也已得到广泛使用。但是，数显技术在精密镗刀上的应用却一直进展缓慢，其制约因素主要是镗孔加工中使用的冷却液和镗头的高速旋转。 过去，在加工中心上进行镗孔加工时必须非常小心，尽量避免四处飞溅的冷却液进入镗头数显装置的电子元件中。如今，采用内冷却设计的新型镗刀已能较好解决这一问题。由于冷却液可通过刀具内部的通道直接到达切削部位，从而实现了冷却液与镗头数显装置的完全隔离。此外，新型数控镗刀的外部进行了良好 密封，可有效防止冷却液与数显装置中的电子元件接触。 在高速镗削加工中，镗头的高速旋转、离心力以及镗头本身的不平衡都可能引起较大振动，从而损坏灵敏的数显装置。新型镗头通过采用一种内置平衡机构，可以在高速镗削时减小或消除有害的振动。目前，带数显读数屏的精密镗头已能够用于转速达 16000r/min的高速镗削加工。 新型镗头的数字显示屏可直接显示出镗刀滑块的位移量，而不必通过调刀螺杆的转动量来确定位移量。由于镗杆直接安装在镗刀滑块上，因此镗头的数显读数值可以真实反映出镗刀的位移量，而不会受到螺杆空程误差的影响。 数显镗头的这一特点使其可以更快速、更精密地调整镗孔直径，并可实现对加工偏差或刀具磨损的误差补偿。 大多数镗刀都需要通过试切测量 (cut-and-measure)操作来确定其设定尺寸，即首先对一小部分被加工孔进行试切镗削，然后测量其加工孔径。通常，这就意味着需要将镗刀从机床上卸下来，再安装到一台对刀仪上对镗刀尺寸进行微调修正，以获得正确的孔径尺寸。这种预调操作之所以必要，是因为直接在机床上对普通镗头的游标刻度盘进行读数和预调相当困难，但是，这种操作方式可能造成镗孔尺寸超差或损坏工件。 由于在机床上安装镗 刀时难以预测其刀尖偏差，因此需要采用试切 测量操作来预调刀具 。如果采用易于读数的新型数显镗刀，则可能实现直接在机床主轴上对刀具镗孔直径进行微调，其尺寸调整范围可达 0.0001 (0.00254mm)。即使因为机床主轴的进刀限制，必须将镗刀从机床上卸下来进行孔径尺寸调整，新型数显镗刀的调刀过程也更快速、更精确。 3.镗床的发展方向 及其特点 现代镗床由过去的专用镗床发展为今天的通用性机床，具有较大的工艺范围，且运动灵活，柔性高，能加工复杂的零件，通用镗床正向 数控 化、大型化、超精密、高速度等方向发展。一些专用镗床向标准化发展，使专用镗床生产周期大为降低，生产成本降低，体积更小，能满足各种加工要求。 在镗床上镗孔时，镗刀基本与车刀相同，不同之处是工件不动，镗刀在旋转。 镗孔加工精度一般为 IT9 IT7，表面粗糙度为 Ra6.3 0.8mm。 4.加工中心上镗孔加工的特点 4.1 刀具转动 和车床加工不同，加工中心加工时由于刀具转动，便不可能在加工中及时掌握刀尖的情况来调节 进刀量等。也不可能像数控车床那样可以只调节数控按扭就可以改变加工直径。这便成了完全自动化加工的一个很大的障碍。也正因为这样所以就要求镗刀必须具有微调机构或自动补偿机能，特别是在精镗时根据公差要求有时必须在微米级调节。另外，加工中心镗孔时由于切屑的流出方向在不断地改变，所以刀尖、工件的冷却以及切屑的排出都要比车床加工时难的多。 4.2 刀具的颠振 镗孔加工时最常出现的、也是最令人头疼问题是颠振。在加工中心上发生颠振的原因主要有以下几点： 1)工具系统的刚性：包括刀柄、镗杆、以及中间连接部分的刚性 。因为是悬臂加工所以特别是小孔、深孔及硬质工件的加工时，工具系统的刚性尤为重要。 2)刀具系统的动平衡：相对于刀具系统的转动轴心，刀具自身如有一不平衡质量，在转动时因不平衡的离心力的作用而导致颠振的发生。特别是在高速加工时刀具的动平衡性所产生影响很大。 3)工件自身或工件的固定刚性：像一些较小、较薄的部件由于其自身的刚性不足，或由于工件形状等原因无法使用合理的夹具进行充分的固定。 4)刀片的刀尖形状：刀片的前角、刀尖半径、断屑槽形状的不同所产生的切削抗力也不同。 5)切削条件 ：包括切削速度、进给量、进刀量以及给切削油方式及种类等。 6)机器的主轴系统：机器主轴自身的刚性、轴承及齿轮的性能以及主轴和刀柄之间的连接刚性。 4.3 刀具的装夹 在镗削孔时，最重要的是在加工中心上正确装夹刀具。在小孔镗削中，刀具的中心高是导致刀具失效的重要因素。如果刀具安装低于中心高，将影响刀具的加工性能。主要表现在： 1)切削刃相对于工件的主后角减小，导致刀具的后刀面与工件接触，使刀片与工件之间发生摩擦，当刀片旋转时，这种摩擦进一步会使刀尖发生偏离，导致刀具更深地切入工件。切削刃 的几何参数对切削效率的高低和加工质量的好坏有很大影响。增大前角，可减小前刀面挤压切削层时的塑性变形，减小切屑流经前面的摩擦阻力，从而减小切削力和切削热。但增大前角，同时会降低切削刃的强度，减小刀头的散热体积。 2)当刀具后角减小时，刀片相对于工件的前角也增大，从而引起刀具刮削工件，引起刀具振动并损坏刀具。这种情况在镗削小孔时更为严重。为此建议刀具安装应略高于中心高 (但应尽可能接近中心高 )。这样可使刀具相对于工件的法向后角增大，切削条件得到改善，如果加工时产生振动，刀尖会向下和向中心偏斜，从而接近理想 的中心高。刀具也可轻微地退出，减小削伤工件的可能性。此外，刀具前角也将减小，这样可稳定工作压力。如果前角减小到 0，就会产生太大的工作压力，导致刀具失效。所以在镗孔时，应选取正前角的镗刀，在镗 1mm 的小孔时，镗杆的直径只有 0.75mm 左右，使刀具承受的切削力减小。 4.4 切屑的排出 在镗削孔时 ，切屑的有效排出至关重要。加工时，由于刀具在孔内，切削液很难到达切削刃，造成切屑排出困难，影响刀具寿命。为解决这一难题，一些刀具制造商开发出一种沿切削刃带冷却槽的刀片，使切削液直接流向切削刃，防止切屑堵塞和刀具 损坏。 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 50s 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 - 0.08m. 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 todays 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 cuttin