机车减震弹簧拆装用10吨四立柱压力机的设计
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1毕业设计(论文)任务书系 部机械工程系指导教师王小平职 称高工学生姓名王豪专业班级05gb机制2学 号0515011223设计题目机车减震弹簧拆装用10吨四立柱压力机的设计设计内容目标和要求针对题目对机车减振弹簧的结构、工况、受力状况等进行调研,并收集整理有关资料,确定压力机的方案,依方案设计减振弹簧拆装用压力机。设计内容及要求1. 收集了解铁路机车减振弹簧的工作情况、结构特点、压力机的工作原理及设计方法,以及有关的机械简图、机械原理、力学、公差与配合 工艺、液压技术等等2. 研究探讨减振弹簧拆装的工艺过程,及其关键的难点是什么,提出解决方案,并对方案进行可行性的分析和论证。3. 对项目方案进行总体设计和部件设计,要求总装图规范,各部件的装配关系要表示清楚,装配工艺要明确,另部件设计要考虑材料、尺寸公差、形位公差、表面粗糙度、热处理、焊接要求、加工工艺性能等等。4. 液压系统的设计要求,了解国内液压行业的状况,绘制液压原理图。5. 设计说明书(论文)。格式要规范,要将所做项目从立项收集资料、调研、方案论证、设计、心得体会等用文字方式规范科学的表达出来,以此锻炼和提高自己的文字表达能力。6. 设计完后要对自己的设计方案进行总结,能否提出水平更高的改进意见。7. 在整个设计中要努力培养和掌握解决此类问题的方法和能力,使自己实际动手能力有一个质的飞跃。8. 进度要求按学院有关规定完成。 指导教师签名: 年 月 日系 部审 核 此表由指导教师填写 由所在系部审核2-1毕业设计(论文)学生开题报告课题名称机车减震弹簧拆装用10吨四立柱压力机的设计课题来源生产实践课题类型AX指导教师王小平学生姓名王豪学 号0515011223专业班级05gb机制2本课题的研究现状、研究目的及意义一、用途该液压机适用于可塑性材料的压制工艺。如粉末制品成型、塑料制品成型、冷(热)挤压金属成型、薄板拉伸以及横压、弯压、翻透、校正等工艺。二 、特点机器具有独立的动力机构和电气系统,采用按钮集中控制,可实现调整、手动及半自动三种工作方式:机器的工作压力、压制速度,空载快下行和减速的行程和范围,均可根据工艺需要进行调整,并能完成顶出工艺,可带顶出工艺、拉伸工艺三种工艺方式,每种工艺又为定压,定程两种工艺动作供选择,定压成型工艺在压制后具有顶出延时及自动回程。 四柱液压机的工作原理油泵把液压油输送到集成插装阀块,通过各个单向阀和溢流阀把液压油分配到油缸的上腔或者下腔,在高压油的作用下,使油缸进行运动.液压机是利用液体来传递压力的设备。液体在密闭的容器中传递压力时是遵循帕斯卡定律。 四柱液压机的液压传动系统由动力机构、控制机构、执行机构、辅助机构和工作介质组成。a 动力机构 通常采用油泵作为动力机构,一般为积式油泵。为了满足执行机构运动速度的要求, 选用一个油泵或多个油泵。低压(油压小于2.5MP)用 齿轮泵;中压(油压小于6.3MP)用叶片泵;高压(油压小于32.0MP)用柱塞泵。各种可塑性材料的压力加工和成形,如不锈钢板钢板的挤压、弯曲、拉伸及金属零件的冷压成形,同时亦可用于粉末制品、砂轮、胶木、树脂热固性制品的压制。四柱液压机简单、经济、实用。外观采用八角形状。控制电器箱采用玻璃门、PLC电脑控制或普通电器两种,具有工作可靠,工作可靠,动作直观,维修方便。独立按扭集中控制。具有调整、双手单次循环二种操作方式。液压控制可采用插装阀集成系统,动作可靠,使用寿命长,液压冲击小,减少了连接管路与泄露点,或普通液压控制两种.四柱液压机具有广泛的通用性适用于各种塑性材料的加工和成形,如挤压、弯曲、折边、拉伸等;同时也可用于各种塑料、粉末制品的压制成形。此外还可以用于制品的校正、压装和整形等。 课题类型:(1)A工程实践型;B理论研究型;C科研装置研制型;D计算机软件型;E综合应用型(2)X真实课题;Y模拟课题;(1)、(2)均要填,如AY、BX等。2-2本课题的研究内容1. 任务提出:设计一个液压系统,运用液压力压缩机车减振弹簧,以便在对减振弹簧检测时的拆装。2. 设计过程: 2.1、阅读零件图,制定设计方案,对设计进行方案分析 2.2、对重点方案分析与计算 2.3、总体方案设计 (1) 设计示意图 (2) 装配示意图(3) 液压系统示意图 2.5 专题设计 小车组件、上板组件、底板组件、立柱、液压系统的设计 2.6 编写设计说明书本课题研究的实施方案、进度安排先自己查阅资料,了解装配过程1周自行设计思路1周参考指导老师的意见,改进自己的方案2周开始设计4周完成实习报告2周2-3已查阅的主要参考文献1 徐 华 主编 机械设计手册(14) 化学工业出版社2 左健民 主编 液压与气压传动第三版 北京:机械工业出版社,2005.53 路甬祥 主编 液压气动技术手册 北京:机械工业出版社,20034 章宏甲 主编 液压与气压传动 北京:机械工业出版社,20035 陆元章 主编 现代机械设备设计手册(2) 北京:机械工业出版社,19966 章宏甲 黄谊 主编液压传动北京:机械工业出版社19937 李天无 主编简明机械工程师手册 北京:北京机械工业出版社19848 彭文生 等 主编机械设计华中理工大学出版社20019 唐增宝 等 主编机械设计课程设计华中理工大学出版社199910上海第二工业大学液压教研室编液压传动与控制 上海科学技术出版社.1975 11 孟少农 主编机械加工工艺手册第3卷 北京:机械工业出版社1992指导教师意见指导教师签名: 年 月 日3毕业设计(论文)学生申请答辩表课 题 名 称机车减震弹簧拆装用10吨四立柱压力机的设计指导教师(职称)申 请 理 由毕业设计任务已完成,说明书已编好。学生所在系部机械工程系专业班级05gb机制2学号0515011223 学生签名: 日期:毕业设计(论文)指导教师评审表序号评分项目(理工科、管理类)评分项目(文科)满分评分1工作量外文翻译152文献阅读与外文翻译文献阅读与文献综述103技术水平与实际能力创新能力与学术水平254研究成果基础理论与专业知识论证能力255文字表达文字表达106学习态度与规范要求学习态度与规范要求15总 分100评语 (是否同意参加答辩) 指导教师签名: 另附毕业设计(论文)指导记录册 年 月 日4毕业设计(论文)评阅人评审表学生姓名王豪专业班级05gb机制2学号0515011223设计(论文)题目机车减震弹簧拆装用10吨四立柱压力机的设计评阅人评阅人职称序号评分项目(理工科、管理类)评分项目(文科)满分评分1工作量外文翻译152文献阅读与外文翻译文献阅读与文献综述103技术水平与实际能力创新能力与学术水平254研究成果基础理论与专业知识论证能力255文字表达文字表达106学习态度与规范要求学习态度与规范要求15总 分100评语 评阅人签名: 年 月 日5毕业设计(论文)答辩表学生姓名王豪专业班级05gb机制2学号0515011223设计(论文)题目机车减震弹簧拆装用10吨四立柱压力机的设计序号评审项目指 标满分评分1报告内容思路清新;语言表达准确,概念清楚,论点正确;实验方法科学,分析归纳合理;结论有应用价值。402报告过程准备工作充分,时间符合要求。103创 新对前人工作有改进或突破,或有独特见解。104答 辩回答问题有理论依据,基本概念清楚。主要问题回答准确,深入。40总 分100答辩组评语 答辩组组长(签字): 年 月 日 答辩委员会意见答辩委员会负责人(签字): 年 月 日6-1毕业设计(论文)答辩记录表学生姓名王豪专业班级05gb机制2学号0515011223设计(论文)题目机车减震弹簧拆装用10吨四立柱压力机的设计答辩时间答辩地点答辩委员会名单张道德,谢成瑜,马丽,王小平问题1提问人: 问题:回答(要点):问题2提问人: 问题:回答(要点):问题3提问人: 问题:回答(要点):记录人签名(不足加附页)6-2问题4提问人: 问题:回答(要点):问题5提问人: 问题:回答(要点):问题6提问人: 问题:回答(要点):问题7提问人: 问题:回答(要点):问题8提问人: 问题:回答(要点):记录人签名7毕业设计(论文)成绩评定总表学生姓名: 王 豪 专业班级: 05gb机制2毕业设计(论文)题目:机车减震弹簧拆装用10吨四立柱压力机的设计成绩类别成绩评定指导教师评定成绩评阅人评定成绩答辩组评定成绩总评成绩40%+20%+40%评定等级注:成绩评定由指导教师、评阅教师和答辩组分别给分(以百分记),最后按“优(90-100)”、“良(80-89)”、“中(70-79)”、“及格(60-69)”、“不及格(60以下)”评定等级。其中, 指导教师评定成绩占40%,评阅人评定成绩占20%,答辩组评定成绩占40%。毕 业 设 计(论 文)机车减振弹簧拆装用10T四立柱压力机的设计学生姓名:王 豪学 号:0515011223所在系部:机械工程系专业班级:05机自本(2)班指导教师:王小平(高工)日 期:2009年6月The motorcycle reduces to flap spring coil to dismantle to pack to use a 10 Ts four sign pillar pressure the design of the machineByHao WangJune 2008毕 业 设 计(论 文)英 文 文 献 翻 译学生姓名:王 豪学 号:0515011223所在系部:机械工程系专业班级:05机自本(2)班指导教师:王小平(高工)日 期:2009年6月 摘 要本论文主要说明机车减震弹簧拆装用10吨四立柱压力机设计的基本过程及工作过程。铁路机车的减振弹簧是铁路机车安全正常运行的重要部件之一,工况差长期处于交变应力的作用下,故必须对它进行定期的检测。故设计10T四立柱压力机对减振弹簧进行拆装,本压力机主要由上板组件、底板组件、立柱、液压系统、小车组件及一些特殊部件,根据工作所需而设计的。论文主要内容包括四大部分:(1)压力机总体方案分析 通过了解加工部件的形状特点及其各个参数,设计几个可行性方案并最终确定压力机的总体方案。(2)压力机的总体设计 确定压力机各部件之间的相互关系,设计简单经济的零部件,绘制机床的尺寸联系图及工作示意图。(3)压力机各部件设计 主要是对底板组件、上板组件、小车组件、立柱等各部件的尺寸设计及其装配设计。(4)液压系统的设计 根据提供的10mp来设计用多大缸径的液压缸,从而设计整个液压系统。关键字:压力机 缸径 组件 设计 过程AbstractThis thesis mainly explains that the motorcycle reduces earthquake spring coil to dismantle to pack to use 10 tons four sign basic process and work process of the pillar pressure machine design.The railroad motorcycle reduces to flap one of the important partses that the spring coil is that the railroad motorcycle is safe to normally circulate, the work condition is bad over a long period of time be placed in to hand over to change in response to the function of the dint next, past have to carry on a periodical examination to it.Past design a 10 Ts four sign pillar pressure machine to flap spring coil to carry on dismantling to pack towards reduce, this pressure enters mainly from top plank module, scaleboard module, sign pillar, liquid to press system, small car module and some special partses, according to work need but design.The thesis main contents include four greatly part of:(1)、Pressure machine the total project be analytical Pass the shape characteristics that understanding processes a parts and it each parameter, design a few possibility projects to combine end assurance pressure machine of total project.(2)、The total design of pressure machineCertain pressure the correlation of of each parts of machine, design in brief economic of zero partses, draw the size of tool machine contact diagram and work sketch map.(3)、Pressure each parts of machine designMainly is to the scaleboard module, ascend plank module, small car module and sign pillar each parts of etc. of size design and its assemble design.(4)、The liquid presses the design of systemDesign to use to have another a big urn the liquid of the path to press an urn according to the 10 mps provide, design the whole liquid to press system thus.Key word: Pressure machine Urn path Module Design Processii目 录摘要iAbstractii1 绪论12 总体方案的设计5 2.1 总体方案 53 液压系统的设计6 3.1 明确系统设计要求 6 3.2 工况分析 6 3.2.1 负载分析 6 3.2.2 运动分析 7 3.3 确定液压缸主要参数 8 3.3.1 确定液压缸 8 3.3.2 初选系统的工作压力 8 3.3.3 计算液压缸的工作面积和流量 9 3.3.4 绘制执行元件工况图 10 3.3.5 拟定液压系统原理图 11 3.4 液压回路的选择 11 3.4.1 选择系统类型 12 3.4.2 选择调速回路 12 3.4.3 选择液压泵的类型 13 3.4.4 选择执行元件 13 3.4.5 选择调压方式 13 3.4.6 选择换向回路 13 3.4.7 绘制原理图 13 3.5 计算和选择液压元件 14 3.5.1选择液压泵 14 3.5.2选择液压控制阀 15 3.5.3 计算泵的驱动功率,选择电机 16 3.5.4辅助元件 17 3.5.5 联轴器的选择 18 3.5.6液压介质的选择 19 3.6 液压系统的性能验算 20 3.6.1 压力损失 20 3.6.2 发热计算 20 3.7 液压装置结构设计 20 3.7.1 液压装置的结构形式 20 3.7.2 液压泵的类型 204 机械系统总图及其各个部件的设计21 4.1 横梁设计 22 4.1.1 横梁的结构设计 22 4.1.2 横梁强度和刚度的校核 24 4.1.3 横梁的固定 30 4.2 立柱设计 31 4.2.1 立柱的结构设计 31 4.2.2 立柱的强度校核 31 4.2.3 立柱的装配配合 33 4.2.4 立柱的预紧 33 4.3 滑动机构(小车)的设计 33 4.3.1 小车结构设计 33 4.3.2 小车关键部件强度校核34 4.3.3 其他零件设计图及小车装配要求35总结38致谢39参考文献 402 High-speed machining and demand for the development ofHigh-speed machining is contemporary advanced manufacturing technology an important component of the high-efficiency, High-precision and high surface quality, and other features. This article presents the technical definition of the current state of development of Chinas application fields and the demand situation.High-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 industries gained increasingly widespread application, and has made significant technical and economic benefits. contemporary advanced manufacturing technology an important component part.HSC is to 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 quantity 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 cutting resistance.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 their 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 materials and the wiring used the tool material, high-speed cutting the meaning is not necessarily the same; Cutting process, bladed through frequency (Tooth Passing Frequency) closer to the machine-tool - Workpiece system the dominant natural frequency (Dominant Natural Frequency), can be considered to be high-speed cutting. Visibility high-speed machining is a comprehensive concept.1992. Germany, the Darmstadt University of Technology, Professor H. Schulz in the 52th on the increase of high-speed cutting for the concept and the scope, as shown in Figure 1. Think different cutting targets, shown in the figure of the transition area (Transition), to be what is commonly called the high-speed cutting, This is also the time of metal cutting process related to the technical staff are looking forward to, or is expected to achieve the cutting speed.High-speed machining of machine tools, knives and cutting process, and other aspects specific requirements. Several were from the following aspects : high-speed machining technology development status and trends.At this stage, in order to achieve high-speed machining, general wiring with high flexibility 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 high-speed and high-speed spindle system feeding system, 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 performance is stronger influence. In the system, the machine spindle stiffness, grip or form, a long knife set, spindle Broach, torque tool set, Performance high-speed impact are important factors.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 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 stage to be successful, a very crucial factor is the dynamic characteristics of the master and processing capability.In order to better describe the machine spindle stiffness characteristics of the project presented new dimensionless 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. 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 more light ceramic ball bearings; Bearing Lubrication most impressive manner mixed with oil lubrication methods. In the field of high-speed machining. have air bearings and the development of magnetic bearings and magnetic bearings and air bearings combined constitute the magnetic gas / air mixing spindle.Feed the machine 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 gyroscopic 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.In recent years, the 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 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. The linear motor is a very time for a continuous machine shop in possession of the bed. Resurfacing of the very meeting where a very early stage movement can go, but the whole system of up to the stiffness without any influence. By using high-speed screw, or linear motor can greatly enhance machine system of up to the rapid response. The maximum acceleration linear motors up to 2-10G (G for the acceleration of gravity), the largest feed rate of up to 60 -200m/min or higher. 2002 world-renowned Shanghai Pudong maglev train project of maglev track steel processing, Using the Shenyang Machine Tool Group Holdings Limited 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 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 distance of up to 30 m, 25 m cutting long maglev track steel error is less than 0.15 mm. Maglev trains for the smooth completion of the project provided a strong guarantee for technologyIn addition, the campaign machine performance will also directly 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 rate 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 or machining parts, the essential processing methods.Cutting Tools Tool Material development high-speed cutting and technological development of the history, tool material is continuous progress of history. The representation 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) has been described as a tool of the 21st century tool, It is particularly applicable to the cutting aluminum alloy containing silica material, which is light weight metal materials, high strength, widely used in the automobile, motorcycle engine, electronic devices shell, the base, and so on. At present, the use of polycrystalline diamond cutter Face Milling alloy, 5000m/min the cutting speed has reached a practical level. In addition ceramic tool also applies to gray iron of high-speed machining; Tool Coating : CBN and diamond cutter, despite good 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 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) coating on the cutter was of great concern. It is expected that the market outlook is very significant; Tool clamping system : Tool clamping system to support high-speed cutting is an important technology, Currently the most widely used is a two-faced tool clamping system. Has been formally invested as a commodity market at the same clamping tool system are : HSK, KM, Bigplus. NC5, AHO systems. In the high-speed machining, tool and fixture rotary performance of the balance not only 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 Parameters Cutting speed of high-speed 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 durability of the tool, Feed volume will also be a corresponding increase about 10 times, reaching 60 m / min, Some even as high as 120 m / min. Therefore, high-speed machining is usually preclude the use of high-speed, feed and depth of cut small cutting parameters. Due to the high-speed machining cutting cushion tend to be small, the formation of very thin chip light, Cutting put the heat away quickly; If the wiring using a new thermal stability better tool materials and coatings, Using the dry cutting process for high-speed machining is the ideal technology program.High-speed machining field of applicationFlexible efficient production lineTo adapt 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 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, this should be subject to appropriate intensive manual processing. Due to the extremely high cutting speed, and the last finishing processes, the processing cycle should be greatly reduced. To play for machining centers and boring and milling machining center category represented by the high-speed machining technology and automatic 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 processes centralized processing and dilute the traditional cars, milling, boring, Thread processing different cutting the limits of technology, equipment and give full play to the high-speed cutting tool function, NC is currently raising machine efficiency and speed up product development in an effective way. Therefore, the proposed multi-purpose tool of the new requirements call for a tool to complete different parts of the machining processes, ATC reduce the number of ATC to save time, to reduce the quantity and tool inventory, and management to reduce production costs. More commonly used in a multifunctional Tool, milling, boring and milling, drilling milling, drilling-milling thread-range tool. At the same time, mass production line, against the use of technology requires the development of special tools, tool or a smart composite tool, improve processing efficiency and accuracy and reduced investment. In the high-speed cutting conditions, and some special tools can be part of the processing time to the original 1 / 10 below, results are quite remarkable. HSC has a lot of advantages such as : a large number of materials 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 life cycle of the workpiece, able to demonstrate high-speed cutting brought advantages.高速切削加工的发展及需求高速切削加工是当代先进制造技术的重要组成部分,拥有高效率、高精度及高表面质量等特征。本文介绍此技术的定义、发展现状、适用领域以及中国的需求情况。高速切削加工是面向21世纪的一项高新技术,它以高效率、高精度和高表面质量为基本特征,在汽车工业、航空航天、模具制造和仪器仪表等行业中获得了愈来愈广泛的应用,并已取得了重大的技术经济效益,是当代先进制造技术的重要组成部分。高速切削是实现高效率制造的核心技术,工序的集约化和设备的通用化使之具有很高的生产效率。可以说,高速切削加工是一种不增加设备数量而大幅度提高加工效率所必不可少的技术。高速切削加工的优点主要在于:提高生产效率、提高加工精度及降低切削阻力。 有关高速切削加工的含义,目前尚无统一的认识,通常有如下几种观点:切削速度很高,通常认为其速度超过普通切削的5-10倍;机床主轴转速很高,一般将主轴转速在10000-20000r/min以上定为高速切削;进给速度很高,通常达15-50m/min,最高可达90m/min;对于不同的切削材料和所釆用的刀具材料,高速切削的含义也不尽相同;切削过程中,刀刃的通过频率(Tooth Passing Frequency)接近于“机床刀具工件”系统的主导自然频率(Dominant Natural Frequency)时,可认为是高速切削。可见高速切削加工是一个综合的概念。1992年,德国Darmstadt工业大学的H. Schulz教授在CIRP上提出了高速切削加工的概念及其涵盖的范围,如图1所示。认为对于不同的切削对象,图中所示的过渡区(Transition)即为通常所谓的高速切削範围,这也是当时金属切削工艺相关的技术人员所期待或者可望实现的切削速度。高速切削加工对机床、刀具和切削工艺等方面都有一些具体的要求。下面分别从这几个方面阐述高速切削加工技术的发展现状和趋势。现阶段,为了实现高速切削加工,一般釆用高柔性的高速数控机床、加工中心,也有釆用专用的高速铣、钻床。这些设备的共同之处是:必须同时具有高速主轴系统和高速进给系统,才能实现材料切削过程的高速化。高速切削与传统切削最大的区别是,“机床刀具工件”系统的动态特性对切削性能有更强的影响力。在该系统中,机床主轴的刚度、刀柄形式、刀长设定、主轴拉刀力、刀具扭力设定等,都是影响高速切削性能的重要因素。 在高速切削中,材料去除率(Metal Removal Rate,MRR),即单位时间内材料被切除的体积,通常受限于“机床-刀具-工件”工艺系统是否出现“颤振”。因此,为了满足高速切削加工的需求,首先要提高机床动静刚度尤其是主轴的刚度特性。现阶段高速切削之所以能够成功,一个很关键的因素在于对系统动态特性问题的掌握和处理能力。为了更好地描述机床主轴的刚度特性,工程上提出新的无量纲参数DN值,用以评价机床的主轴结构对高速切削加工的适应性。所谓DN值即“主轴直径与每分钟转速之积”。新近开发的加工中心主轴DN值大都已超过100万。为了减轻轴承的重量,还釆用了比钢制品要轻得多的陶瓷球轴承;轴承润滑方式大都釆用油气混合润滑方式。在高速切削加工领域,目前已开发空气轴承和磁轴承以及由磁轴承和空气轴承合并构成的磁气/空气混合主轴。 在机床进给机构方面,高速切削加工所用的进给驱动机构通常都为大导程、多头高速滚珠丝槓,滚珠釆用小直径氮化硅(Si3N4)陶瓷球,以减少其离心力和陀螺力矩;釆用空心强冷技术来减少高速滚珠丝槓运转时由于摩擦产生温升而造成的丝槓热变形。近几年来,用直线电机驱动的高速进给系统问世,这种进给方式取消了从电动机到工作台溜板之间的一切中间机械传动环节,实现了机床进给系统的零传动。由于直线电机没有任何旋转元件,不受离心力的作用,可以大大提高进给速度。直线电机的另一大优点是行程不受限制。直线电机的次极是一段一段连续铺在机床的床身上。次极铺到哪里,初极工作台就可运动到哪里,而且对整个进给系统的刚度没有任何影响。釆用高速丝槓或直线电机,能够大大提高机床进给系统的快速响应。直线电机最高加速度可达2-10G(G为重力加速度),最大进给速度可达60-200m/min或更高。2002年举世瞩目的上海浦东磁悬浮列车工程中的磁浮轨道钢梁加工,釆用沈阳机床控股有限公司集团中捷友谊公司厂生产的超长进给系统高速大型加工中心实现。该机床的进给系统为直线导轨和齿轮齿条传动,工作台最大进给速度60m/min,快速行程100m/min,加速度2g,主轴最高转速20000r/min,主电机功率80kW。其X轴的行程长达30m,切削25m长的磁浮轨道钢梁误差小于0.15mm,为磁悬浮列车工程的顺利竣工提供了有力的技术保证。此外,机床的运动性能也将直接影响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,主要釆用小切深大进给的加工方法。要求机床在大进给速度条件下,应具有高精度定位功能和高精度插补功能,特别是圆弧高精度插补。圆弧加工是釆用立铣刀或螺纹刀具加工零部件或模具时,必不可少的加工方法。刀具材料的发展:高速切削技术发展的历史,也就是刀具材料不断进步的历史。高速切削的代表性刀具材料是立方氮化硼(CBN)。端面铣削使用CBN刀具时,其切削速度可高达5000m/min,主要用于灰口铸铁的切削加工。聚晶金刚石(PCD)刀具被称之为21世纪的刀具,它特别适用于切削含有SiO2的铝合金材料,而这种金属材料重量轻、强度高,广泛地应用于汽车、摩托车发动机、电子装置的壳体、底座等方面。目前,用聚晶金刚石刀具端面铣削铝合金时,5000m/min的切削速度已达到实用化水平,此外陶瓷刀具也适用于灰口铸铁的高速切削加工;涂层刀具:CBN和金刚石刀具尽管具有很好的高速切削性能,但成本相对较高。釆用涂层技术能够使切削刀具既价格低廉,又具有优异性能,可有效降低加工成本。现在高速加工用的立铣刀,大都釆用TiAIN系的复合多层涂镀技术进行处理,如目前在对铝合金或有色金属材料进行干式切削时,DLC(Diamond Like Carbon)涂层刀具就受到极大的关注,预计其巿场前景十分可观;刀具夹持系统:刀具的夹持系统是支撑高速切削的重要技术,目前使用最为广泛的是两面夹紧式工具系统。已作为商品正式投放巿场的两面夹紧式工具系统主要有:HSK、KM、Bigplus、NC5、AHO等系统。 在高速切削的情况下,刀具与夹具回转平衡性能的优劣,不仅影响加工精度和刀具寿命,而且也会影响机床的使用寿命。因此,在选择工具系统时,应尽量选用平衡性能良好的产品。高速加工的切削速度为常规切速的10倍左右。为了使刀具每齿进给量基本保持不变,以保证零件的加工精度、表面质量和刀具的耐用度,则进给量也必须相应提高10倍左右,达到60m/min以上,有的甚至高达120m/min。因此,高速切削加工通常是釆用高转速、大进给和小切深的切削工艺参数。由于高速切削的切削余量往往很小,所形成的切屑很薄很轻,把切削时产生的热量很快带走;若釆用全新耐热性更好的刀具材料和涂层,釆用干切削工艺也是高速切削加工的理想工艺方案。用高速加工中心组成高效率的柔性生产线(FTL或FML),具有小型化、柔性突出以及易于变更加工内容等显着特点。图2为上汽集团某发动机公司利用该生产线加工发动机机体、汽缸盖、滤清器座等工件的实例。为了尽快适应新车型的需要,汽车车身覆盖件模具和树脂防冲挡的成形模具等,均必须缩短制作周期和降低生产成本,因此,必须下大力推进模具生产高速化的进程。上汽集团所属各公司认为:与过去的精加工相比,进一步实现高精度化;同时必须满足表面粗糙度、弯曲度的精度要求,为此应施以适当的手工精修加工,由于切削速度的极大提高,与过去的精加工工序相比,加工周期应大幅度缩短。为了发挥以车削加工中心和镗铣类加工中心为代表的高速切削加工技术和自动换刀功能的优势,提高加工效率,对复杂零件的加工应尽可能釆用集中工序的原则,即要求在一次装夹中实现多道工序的集中加工,淡化传统的车、铣、镗、螺纹加工等不同切削工艺的界限,充分发挥设备和刀具的高速切削功能,是当前提高数控机床效率、加快产品开发的有效途径。为此,对刀具提出了多功能的新要求,要求一种刀具能完成零件不同工序的加工,减少换刀次数,节省换刀时间,以减少刀具的数量和库存量,有利于管理和降低制造成本。较常用的有多功能车刀、铣刀、镗铣刀、钻铣刀、钻铣螺纹倒角等刀具。与此同时,在批量生产线上,使用针对工艺需要开发的专用刀具、复合刀具或智能刀具,可以提高加工效率和精度,减少投资。在高速切削条件下,有的专用刀具可将零件的加工时间降至原来的1/10以下,效果十分显着。高速切削具有相当多的好处,例如:有大量材料需要切除的工件,具有超细、薄结构的工件,传统上需要花相当长的机动工时加工的工件以及设计变更快速、产品周期短的工件,均能显示出高速切削所带来的优点。阅读书目1李兆铨,周明研机械制造技术M北京:中国水利水电出版社,2005.2左健民,液压与气压传动M北京:机械工业出版社,1999.3王为,汪建晓机械设计M武汉:华中科技大学出版社,2007.4赵大兴,李天宝,赵成刚现代工程图学M武汉:湖北科学技术出版社,20055孙波毕业设计宝典M西安:西安电子科技大学出版社,2008.6赵月静,宁辰校液压实用回路360例M北京:化学工业出版社,2007.7机械设计手册编写组机械设计手册M北京:机械工业出版社.8吴振顺液压控制系统M北京:高等教育出版社,2007.9陈立德机械制造装备设计课程设计M北京:高等教育出版社,2007.10唐增宝,常建娥机械设计课程设计M 武汉:华中科技大学出版社 2006.
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