第一篇：机械专业英语复试词汇总结（推荐）

机械英语词汇大全2

金属切削 metal cutting 机床 machine tool

拉孔 broaching 装配 assembling

数学模型 mathematical model

画法几何 descriptive geometry 金属工艺学 technology of metals 刀具 cutter 摩擦 friction 联结 link 传动 drive/transmission 轴 shaft 弹性 elasticity 频率特性 frequency characteristic 误差 error 响应 response 定位 allocation 机床夹具 jig 动力学 dynamic 运动学 kinematic 静力学 static 分析力学 analyse mechanics 拉伸 pulling 压缩 hitting 剪切 shear

铸造 found 流体动力学 fluid dynamics 机械制图 Mechanical drawing 流体力学 fluid mechanics 投影 projection 加工 machining

视图 view

液压 hydraulic pressure 剖视图 profile chart 切线 tangent

标准件 standard 机电一体化 mechanotronics

component

mechanical-electrical integration

零件图 part drawing 气压 air pressure pneumatic pressure 装配图 assembly drawing

稳定性 stability 尺寸标注 size marking 介质 medium

技术要求 technical 液压驱动泵 fluid clutch requirements 液压泵 hydraulic pump 刚度 rigidity 阀门 valve 内力 internal force 失效 invalidation 位移 displacement 强度 intensity 截面 section

载荷 load 疲劳极限 fatigue limit 应力 stress

断裂 fracture 安全系数 safty factor

塑性变形 plastic distortion 扭转 twist 弯曲应力 bending stress 强度 intensity 三相交流电 three-phase AC 磁路 magnetic circles 变压器 transformer 异步电动机 asynchronous motor 几何形状 geometrical 精度 precision 正弦形的 sinusoid 交流电路 AC circuit 机械加工余量 machining allowance 变形力 deforming force 变形 deformation 应力 stress 硬度 rigidity 热处理 heat treatment 退火 anneal 正火 normalizing 脱碳 decarburization 渗碳 carburization 电路 circuit 半导体元件 semiconductor

可靠性 reliability 螺纹 thread 螺旋 helix 键 spline 销 pin

滚动轴承 rolling bearing

滑动轴承 sliding bearing 弹簧 spring

制动器 arrester brake 十字结联轴节 crosshead 联轴器 coupling 链 chain 皮带 strap

精加工 finish machining

粗加工 rough machining

变速箱体 gearbox casing

腐蚀 rust

氧化 oxidation

磨损 wear

耐用度 durability

随机信号 random signal

离散信号 discrete signal

超声传感器 ultrasonic sensor

脆性材料 brittleness material

刚度准则 rigidity criterion 垫圈 washer 垫片 spacer

直齿圆柱齿轮 straight toothed spur gear 斜齿圆柱齿轮

helical-spur gear 直齿锥齿轮 straight bevel gear 运动简图 kinematic sketch

齿轮齿条 pinion and rack

蜗杆蜗轮 worm and worm gear

虚约束 passive constraint 曲柄 crank 摇杆 racker 凸轮 cams

共轭曲线 conjugate curve

范成法 generation method

定义域 definitional domain element 反馈 feedback 发生器 generator 直流电源 DC electrical source 门电路 gate circuit 逻辑代数 logic algebra 外圆磨削 external grinding 内圆磨削 internal grinding平面磨削 plane grinding 变速箱 gearbox 离合器 clutch 绞孔 fraising 绞刀 reamer 螺纹加工 thread processing 螺钉 screw 铣削 mill 铣刀 milling cutter 功率 power 工件 workpiece 齿轮加工 gear mechining 齿轮 gear 主运动 main movement 主运动方向 direction of main

集成电路 integrate circuit 挡板 orifice plate 残余应力 residual stress

套筒 sleeve 扭力 torsion

冷加工 cold machining 电动机 electromotor 汽缸 cylinder

过盈配合 interference fit 热加工 hotwork 摄像头 CCD camera 倒角 rounding chamfer 优化设计 optimal design

工业造型设计 industrial moulding design

有限元 finite element

滚齿 hobbing

插齿 gear shaping

伺服电机 actuating motor

铣床 milling machine

钻床 drill machine

镗床 boring machine

步进电机 stepper motor

值域 range 导数微分 differential coefficient 求导 derivation 定积分 definite integral

不定积分 indefinite integral 曲率 curvature 偏微分 partial differential 毛坯 rough

游标卡尺 slide caliper 千分尺 micrometer calipers

攻丝 tap 二阶行列式 second order determinant 逆矩阵 inverse matrix 线性方程组 linear equations 概率 probability 随机变量 random variable

排列组合 permutation and combination 气体状态方程 equation movement 进给方向 direction of feed 进给运动 feed movement

丝杠 screw rod 导轨 lead rail 组件 subassembly

of state of gas 动能 kinetic energy 势能 potential energy 合成进给运动 resultant movement 可编程序逻辑控制器 Programmable 机械能守恒 of feed Logic Controller PLC conservation of

mechanical energy 合成切削运动 resultant movement 电火花加工 electric spark of cutting machining 动量 momentum 合成切削运动方向 direction of 电火花线切割加工 electrical resultant movement of cutting discharge wire-cutting 切削深度 cutting depth 前刀面 rake face 刀尖 nose of tool 前角 rake angle 后角 clearance angle 龙门刨削 planing 主轴 spindle 主轴箱 headstock 卡盘 chuck

悬架 suspension 加工中心 machining center

转向器 redirector 车刀 lathe tool 车床 lathe 钻削 镗削 bore

变速器 speed changer

基准 benchmark

回火 tempering 调质 hardening and tempering

磨粒 abrasive grain 结合剂 bonding agent 淬火 hardening 淬火冷却 quench

相图 phase diagram

余子式 cofactor

热处理 heat treatment

逻辑电路 logic circuit

固态相变 solid state phase changes

触发器 flip-flop

有色金属 nonferrous metal

脉冲波形 pulse shape

陶瓷 ceramics

数模 digital analogy

合成纤维 synthetic fibre

液压传动机构 fluid

电化学腐蚀 electrochemical drive mechanism corrosion

机械零件 mechanical

车架 automotive chassis parts

桁架 truss 轴线 axes

砂轮 grinding wheel 工程技术人员 engineer 气动夹紧 pneuma lock 孔加工 spot facing machining 车间 workshop 板料冲压 sheet metal parts 磨床 grinder

第二篇：机械专业英语

机械专业英语杨亚炬 20100334506

机电103班

考虑磨削力的磁悬浮磨床电主轴转子系统动态特性分析

摘要:以电磁轴承支承的磨床也主轴为研究对象，建立了转子的弹性支承模型，对其进行了模态分析，得出转子固有频率随支承刚度变化的规律;对施加磨削力时转子的稳态响应特性进行了分析，根据危险界面的节点位移，初步确定了主轴系统的稳定性。

关键词:电磁轴承支承系统;磨床电主轴;模态分析;稳态响应特性 引言

电磁轴承具有无摩擦、元磨损、高速度、高精度及可长期免维护等优点，因此被广泛应用于高速旋转类机械中。采用电磁轴承支承的磨床电主轴是典型的机电一体化系统，由于磨削过程的复杂性，其支承主轴系统的影响与其他轴承相比更为突出[1 刀。转子的动态特性是电磁轴承支承特性与转子结构动力学特性综合作用的结果。在对转子实施控制之前，研究转子本身的动力学行为对控制系统的设计是很重要的时。本文以某电磁轴承支承的磨床电主轴为研究对象，建立了转子的弹性支承模型，对其进行了模态分析和施加磨削力时的稳态响应特性分析。轴、砂轮连接杆、前后径向轴颈套、前后平衡环、止推盘和隔磁环等组成，其他部件与转轴之间采用过盈连接。

转子总重5.90kg，总长507mm，稳定悬浮时转子和径向轴承之间的间隙为0.2mm，轴向轴承

1.砂轮2 传感器3.前辅助轴承4.前径向轴承5.转轴6.轴向轴承7.冷却水套

8.电机部分9.后径向轴承10.后辅助轴承间隙为0.3mm。建立有限元模型

电磁轴承支承为典型的弹性支承，有限元分析模型采用16 个弹簧单元模拟径向电磁轴承的16 个磁极。止推盘两侧分别采用8 个弹簧转轴 根据转子的结构形式，用ANSYS 建立起转子的实体有限元分析模型，模态分析

支承刚度对转子固有频率的影晌根据转子的有限元分析模型，用ANSYS 对其进行模态分析[5J。忽略弹簧单元的阻尼，支承刚度在5X106~lXI09N/m 范围内变化阶模态，得到转子的正进动固有频率和负进动固有频率，进一步研究临界转速时，首先剔除负进动固有频率[6J。可以得到转轴前四阶固有频率随刚度变化曲线,转子的正进动固有频率随支承刚度的增大而增大，且转子的低阶固有频率随支承刚度增加的幅度较大。当支承刚度增大到1.6X10 8 N/m 时，转子的2~4 阶固有频率已无多

模态分析完毕后，将磨削激振力施加于砂轮 处进行谐响应分析，在砂轮外圆节点7746 处施加Y 方向力(实部为88.328N、虚部为1.9737N)和Z 方向力(实部为1.9737N、虚部为88.328N)，这样磨削力为一简谐力。COMBIN14 单元的刚度取2.0X10 7 N/m，为分析转子在高频段的响应，将激振力的频率范围扩大至0~1600Hz，分20 个载荷步进行谐响应分析。

当主轴工作在30000r/ min(对应额定工作频率500.0Hz)、48 OOOr/ min(对应最高工作频率800.OHz)，即转速处于一阶与二阶临界转速之间时，由转子的二阶振型(图5)可以看出，转子在砂轮、前保护轴承、前径向轴承和后径向轴承处的中心截面为危险截面。图7~ 图10 分别为砂轮、前保护轴承、前径向轴承和后

径向轴承处的振动幅值一频率响应后径向轴承处节点4484 振动幅值一频率响应曲线移增大幅值在一阶固有频率处最小，二阶固有频率处最大，三阶固有频率处次之。

磨床电主轴的结构参数如下:转子与前后保护轴承的间隙为O.lmm，与前后径向轴承的间隙为0.2mm。由表3 可知，当激振力频率达到转子一阶、三阶固有频率时，转子产生的共振位移在转曲线，在有限元模型上分别对应节点7746、7818、7559 和4484 的振动幅值频率响应。各危险截面的节点Y 方向位移如表3 所示。当激振力频率达到转子的固有频率时，转子的位移(振动幅值)会突然增大，通过前三阶的幅频响应曲线可以看出，转子位子间隙范围之内;但达到转子二阶固有频率时，转子产生的共振位移会超出间隙要求，使得转子与轴承碰撞，发生危险，因此应避免激振力频率达到转子的二阶固有频率。由转子的二阶振型可以看出，转子在后保护轴承处的径向位移小于后径向轴承处的径向位移，故可判定后保护轴承处在Y 方向的位移小于

2.0 X 10 一7 m。各危险截面的节点位移均在间隙范围内，因此可初步判定转子在额定转速和最高

转速下工作时，给其施加Fn = 88.328N、Ft =1.9737N 的磨削力，可稳定工作。结论

(1)完全弹性支承下，电主轴转子固有频率的总体变化趋势随支承刚度的增大而增大，并且在支承刚度较低时，固有频率随支承刚度的变化较大。当支承刚度到达一定值时，转子的前四阶固有频率趋于稳定，在设计控制系统时可控制轴承的刚度高于此值，以便转子具有稳定的临界转速。

(2)在施加了磨削激振力后，通过幅值频率响应分析确定了几个危险界面的节点位移，可初步判断主轴系统的稳定性。

Dynamic Analysis for Electric Spindle Rotor System of Magnetic Levitation Grinder

Considering Grinding Force

Abstract: This paper bui1t an elastic bearing model for the rotor of grinder electric spindlesupported by electromagnet bearing and analyzed the mode of the rotor , educed the laws about therotor inherent frequencies changing along with bearing stiffness.Then, it analyzed steady stateresponse characteristics of the rotor while applying grinding force.According to the nodedisplacements of danger interface ,stability of spindle system is ensured initially.Key words: supporting system of electromagnet bearing;grinder electric spindle;mode analysis;steady state response characteristics.Introduction

Electromagnetic bearings with no friction, wear yuan, high-speed, high precision and long-term maintenance-free, etc., it is widely used in high-speed rotating machinery.The electromagnetic bearing grinder electric spindle is a typical mechatronic systems, due to the complexity of the grinding process, the supporting spindle system compared with other bearing more prominent [1 knife.The dynamic characteristics of the rotor the electromagnetic bearing characteristics and rotor structure dynamics combined result.Before control of the rotor embodiment, the study rotor dynamic behavior of the control system design is very important.An electromagnetic bearing grinder electric spindle rotor elastic support model, its modal analysis and steady-state response characteristics in the grinding force is applied.Shaft, wheel connecting rod, front and rear radial journal cover, front and rear stabilizer ring, thrust plate, and every other magnetic interference connection between the other components and the shaft.The rotor total weight of 5.90kg, Total length 507mm, stable suspension of the rotor and the radial bearing gap of 0.2mm, and the axial bearingwheel sensor 3.Former auxiliary bearing front radial bearing 5.Shaft axial bearing cooling water jacket motor section 9 after radial bearing 10 after the auxiliary bearing clearance of 0.3 mm.Finite element model

The electromagnetic bearing the typical elastic support, finite element analysis model with 16 spring element to simulate the radial magnetic bearing 16 pole.On both sides of the thrust plate 8 spring pivot

Established with ANSYS based on the structure of the rotor, the rotor solid finite element analysis model, Modal Analysis Support stiffness IMPACT natural frequency

of the rotor based on the finite element analysis model of the rotor, modal analysis using ANSYS its [5J.The damping of the spring element is ignored, the the support stiffness 5X106 ~ lXI09N / m range order modal rotor is precession natural frequencies and negative precession natural frequency, further study of the critical speed, the first natural frequency [excluding the negative precession 6J.Can get the shaft first four natural frequency of the curve with the change in stiffness of the rotor is precession natural frequency with the support stiffness increases, and the rate of increase of the low-order natural frequency of the rotor with the bearing stiffness.The 2-4 order natural frequency of the rotor Found when the supporting stiffness increases to 1.6X10 8 N / m,Modal analysis after grinding exciting force is applied at the wheel at the harmonic response analysis, the Y direction of the force applied to the wheel outer node 7746(88 328N real part, imaginary part 1 9737N), and Z directions force(the real part of 9737N, the imaginary part of the 88 328N), so that the grinding force of a simple harmonic force.COMBIN14 element stiffness take 2.0x10 7 N / m for the analysis of the response of the rotor at high frequencies, the frequency range of the excitationforce is expanded to 0 to 1600Hz, 20 load step harmonic response analysis.Spindle 30000r / min(corresponding to the nominal operating frequency 500.0Hz), of 48 OOOr / min(corresponding to the maximum operating frequency of 800 OHZ)that speed in the first-order and second-order critical speed, the second rotor vibration type(Figure 5)can be seen, the rotor wheel, the front protective bearings, the radial bearing and the rear radial bearing at the center of a sectional view of the dangerous section.Figures 7 to 10 respectively for the wheel, the front protective bearings, the front radial bearing and a radial bearing at a frequency response of the vibration amplitude of the vibration amplitude of the radial bearing at the node 4484 frequency response curve shift increased amplitude in a The natural frequencies at the minimum, followed by the natural frequency of the second-order, third-order natural frequency.Of Grinder Spindle structure parameters are as follows: rotor protection before and after bearing clearance O.lmm the front and rear radial bearing clearance of 0.2 mm.Seen from Table 3, when the frequency of the excitation force to the rotor-order, third-order natural frequency, the resonance generated by the rotor displacement in the transfer curve in the finite element model, respectively corresponding to the nodes 7746, 7818, 7559 and 4484, the amplitude of vibration frequency response.The nodes in the Y direction of the dangerous section of the displacement shown in Table 3.When the frequency of the excitation force is reached when the natural frequency of the rotor, the rotor displacement(vibration amplitude)will suddenly increases, frequency response curve of the web through the first three can be seen, within the scope of the clearance of the rotor charts;but reached rotor Second Order natural frequency of the rotor of the resonance displacement will exceed the spacing requirements, so that the rotor and the bearing collision danger, the second natural frequency of the exciting force the frequency of the rotor should therefore be avoided.By the second-order vibration of the rotor can be seen, the radial displacement of the rotor after protection of the radial displacement of the bearing

is less than the radial bearing at the displacement of the bearings in the Y direction, it can be determined after protection Smaller

2.0 X 10 a m.Of the dangerous section of the nodal displacements gap preliminary determination rotor at rated speed and maximum

Speed work when applied to its Fn = 88.328N FT = 9737N grinding force can work stably.Conclusions

(1)fully resilient support, the overall trend of the natural frequency of the electro-spindle rotor with bearing stiffness increases, and the supporting rigidity is low, the larger the change of the natural frequency with the support stiffness.When the supporting rigidity reaches a certain value, the first four natural frequencies of the rotor is stabilized in the design of the control system can control the stiffness of the bearing is higher than this value, the stability of the critical speed for the rotor having.(2)In the grinding exciting force is applied by the amplitude frequency response analysis identified several risk interface nodal displacements can determine the initial stability of the spindle system.

第三篇：机械复试经验（范文模版）

同济大学机械复试、早上9：00开会，说明复试安排，要调剂的先领表，这些事在10：00之前做完、10：00开始进入复试阶段，每个专业一个教室，发专业课试卷和专业英语试卷，在下午1：00之前做完，由两个研究生监考。期间，按进入复试名单字母排序，专业综合面试，从A开始，英语口语、听力从Z往前排，由监考老师点名去面试和口语。面试和口语分开，分别完成后回来做试卷，所有的复试内容在下午1：00结束。

3、专业英语：8段专业英语的英文，将他们翻译成英文。

机械制造基础：

1）填空题

2）简答题

3）计算题----a、计算定位误差b、分析制造误差：求不合格率、常值系统误差、系统刚度c、安排工序尺寸

4、专业综合面试：1）三位老师2）先自我介绍，然后问你毕业设计或者你做过的作品，例如机械设计大赛。3）带好你在大学里获得的奖

口语听力：三位老师；自我介绍、读一段专业英语--读一句翻译一句，口头现场翻译

个人体会：准备充分（我那几道计算题都没怎么写完整，都是课后题类型的，平时不用心）、早饭吃的饱（下午1点才结束）、提前跟导师联系（专业面试我那一组的老师，其中一个复试前面谈过，一个成绩出来第二天就联系了，一个是我老乡

第四篇：大学机械专业英语总结

Unit 11 Machine tools have evoled from the early foot-powered lathes of the Egyptians and John Wilkinson’s boring mill.Most machining operations produce parts of differing geometry.Flat or plain surfaces are frequently required.Multiple-edged tools can also be used.The basic operations performed on an engine lathe are illustrated in Fig11-3.Those operations performed on external surfaces with a single point cutting tool are called turning.The objective of boring a hole in a lathe is:

1.Toenlarge the hole 2,Tomachine the hole to the desired diameter.3.To accurately locate the position of the hole.4.To obtion a smoth surface finish in the hole.Unit12 Broaching is a process for internal or external machining of falt, round, or contoured surfaces.Sawing is the parting of material by using metal disks, blades, bands, or abrasive disks as the cutting tools, Reaming is a machining process for enlarging, smoothing and/or accurately sizing existing holes by means of multiedge flutes cutting tools.Unit 13 Welding is essential to the expansion and productivity of our industries.Electroplating is a process in which a metal is deposited onto a metallic substrate.Soldering is the joining of metals by causing a lower-melting-point metal to wet or alloy with the joint surfaces and then freeze in place.Cleaning operations are performed both preparatory to and after finishing operations.Unit 14 Lathes are designed to rotate the workpiece and feed the cutting tool in the direction necessary togenerate the required machined surface.Vertical-boring machine

horizontal-boring machine

planning machine

horizontal-milling machine

vertical-milling machine Unit 15 AJM removes material through the mechanical cation of a focused stream of abrasiveladen gas.USM is a mechanical material removal process which is used to generate holes and cavities in hard or brittle workpieces.ECM is a process that removes material through the ptinciple of eiectrolysis.Unit 16 Group technology is a very important methodology in today’s manufacturing environment, particularly for batch production, and is becoming increasingly significant.For parts to be grouped based on either design characteristics and featuers or manufacturing processes, they must be classified into predetermined categories and coded for retrieval and use.Unit 17 Flexibility is an important characteristic in the modern manufacturing setting.Cellular manufacturing is the concept of organizing plant facilities and process planning for family-of-part manufactuer.Machine centers originsted out of their capability to perform a variety of machining operations on a workpiece by changing their own cutting tools.Software is the vital invisible element than actually drives the FMS.There are two basic levels of software required for an FMS: 1:operating system 2:application software Unit 18 Computer integrated manufacturing is the term used to describe the modern approach to manufacturing.Management is the process of making directing the activities of personnel to achieve stated objectives.An AGV is a computer-controlled, driverless vehicle used for transporting materials form point in a manufacturing setting.In any discussion of AGVs, three key terms are frequently used: 1:Guide path.2:Routing.3:Traffic management.Unit 19 Part acquisition time is highly dependent on the nature of the layout of the assenmbly area and the method of assembly.Assembly in the manufacturing process consists of putting together all the component parts and sub-assemblies of a given product, fastening, performing inspections and functional tests, labeling, separating good assemblies from bad, and packaging and or preparing them for final use.Unit 20

Automation is a widely used term in manufacturing.Fixed automation is what Harder was referring to when he coined the word automation.Numerical control can be defined as a form of programmable automation in which the pross is controlled by numbers, letters, and symbols.The program of instructions is the detailed step-by-step set of directions which tell the machine tool what to do.The highest degree of automation obtainable with special-purpose, multifunction machines is achieved by using transfer machines.

第五篇：机械专业英语文章中英文对照

英语原文

NUMERICAL CONTROL

Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols, The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work part or job.When the job changes, the program of instructions is changed.The capability to change the program is what makes N/C suitable for low-and medium-volume production.It is much easier to write programs than to make major alterations of the processing equipment.There are two basic types of numerically controlled machine tools：point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors, with the result that the position of the machining head Can be assured only upon completion of a movement, or while only one motor is running.Machines of this type are principally used for straight—line cuts or for drilling or boring.The N/C system consists of the following components：data input, the tape reader with the control unit, feedback devices, and the metal—cutting machine tool or other type of N/C equipment.Data input, also called “man—to—control link”, may be provided to the machine tool manually, or entirely by automatic means.Manual methods when used as the sole source of input data are restricted to a relatively small number of inputs.Examples of manually operated devices are keyboard dials, pushbuttons, switches, or thumbwheel selectors.These are located on a console near the machine.Dials ale analog devices usually connected to a syn-chro-type resolver or potentiometer.In most cases, pushbuttons, switches, and other similar types of selectors are digital input devices.Manual input requires that the operator set the controls for each operation.It is a slow and tedious process and is seldom justified except in elementary machining applications or in special cases.In practically all cases, information is automatically supplied to the control unit and the machine tool by cards, punched tapes, or by magnetic tape.Eight—channel punched paper tape is the most commonly used form of data input for conventional N/C systems.The coded instructions on the tape consist of sections of punched holes called blocks.Each block represents a machine function, a machining operation, or a combination of the two.The entire N/C program on a tape is made up of an accumulation of these successive data blocks.Programs resulting in long tapes all wound on reels like motion-picture film.Programs on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loop.Once installed, the tape is used again and again without further handling.In this case, the operator simply loads and1

unloads the parts.Punched tapes ale prepared on type writers with special tape—punching attachments or in tape punching units connected directly to a computer system.Tape production is rarely error-free.Errors may be initially caused by the part programmer, in card punching or compilation, or as a result of physical damage to the tape during handling, etc.Several trial runs are often necessary to remove all errors and produce an acceptable working tape.While the data on the tape is fed automatically, the actual programming steps ale done manually.Before the coded tape may be prepared, the programmer, often working with a planner or a process engineer, must select the appropriate N/C machine tool, determine the kind of material to be machined, calculate the speeds and feeds, and decide upon the type of tooling needed.The dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the program.A program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specifications.The control unit receives and stores all coded data until a complete block of information has been accumulated.It then interprets the coded instruction and directs the machine tool through the required motions.The function of the control unit may be better understood by comparing it to the action of a dial telephone, where, as each digit is dialed, it is stored.When the entire number has been dialed, the equipment becomes activated and the call is completed.Silicon photo diodes, located in the tape reader head on the control unit, detect light as it passes through the holes in the moving tape.The light beams are converted to electrical energy, which is amplified to further strengthen the signal.The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives.Some photoelectric devices are capable of reading at rates up to 1000 characters per second.High reading rates are necessary to maintain continuous machine—tool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operations.The reading device must be capable of reading data blocks at a rate faster than the control system can process the data.A feedback device is a safeguard used on some N/C installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine tool.An N/C machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop system.Positioning control is accomplished by a sensor which, during the actual operation, records the position of the slides and relays this information back to the control unit.Signals thus received ale compared to input signals on the tape, and any discrepancy between them is automatically rectified.In an alternative system, called an open—loop system, the machine is positioned solely by stepping motor drives in response to commands by a controllers.There is one basic type of NC motions.Point-to-point or Positional Control In point-to-point control the machine tool elements(tools, table, etc.)are moved to programmed locations and the machining operations performed

after the motions are completed.The path or speed of movement between locations is unimportant;only the coordinates of the end points of the motions are accurately controlled.This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece.Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining.It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined.This type of controlled motion is often referred to as linear control or a half-axis of control.Machines with this form of control are also capable of point-to-point control.The original N/C used the closed—loop system.Of the two systems, closed and open loop, closed loop is more accurate and, as a consequence, is generally more expensive.Initially, open—loop systems were used almost entirely for light-duty applications because of inherent power limitations previously associated with conventional electric stepping motors.Recent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applications.中文译文

数控技术

数控是可编程自动化技术的一种形式,通过数字、字母和其他符号来控制加工设备。数字、字母和符号用适当的格式编码为一个特定工件定义指令程序。当工件改变时,指令程序就改变。这种改变程序的能力使数控适合于中、小批量生产,写一段新程序远比对加工设备做大的改动容易得多。

数控机床有两种基本形式：点位控制和连续控制(也称为轮廓控制)。点位控制机床采用异步电动机,因此,主轴的定位只能通过完成一个运动或一个电动机的转动来实现。这种机床主要用于直线切削或钻孔、镗孔等场合。

数控系统由下列组件组成：数据输入装置,带控制单元的磁带阅读机,反馈装置和切削机床或其他形式的数控设备。

数据输人装置,也称“人机联系装置”,可用人工或全自动方法向机床提供数据。人工方法作为输人数据唯一方法时,只限于少量输入。人工输入装置有键盘,拨号盘,按钮,开关或拨轮选择开关,这些都位于机床附近的一个控制台上。拨号盘通常连到一个同步解析器或电位计的模拟装置上。在大多数情况下,按钮、开关和其他类似的旋钮是数据输入元件。人工输入需要操作者控制每个操作,这是一个既慢又单调的过程,除了简单加工场合或特殊情况,已很少使用。

几乎所有情况下,信息都是通过卡片、穿孔纸带或磁带自动提供给控制单元。在传统的数控系统中,八信道穿孔纸带是最常用的数据输入形式,纸带上的编码指令由一系列称为程序块的穿孔组成。每一个程序块代表一种加工功能、一种操作或两者的组合。纸带上的整个数控程序由这些连续数据单元连接而成。带有程序的长带子像电影胶片一样绕在盘子上,相对较短的带子上的程序可通过将纸带两端连接形成一个循环而连续不断地重复使用。带子一旦安装好,就可反复使用而无需进一步处理。此时,操作者只是简单地上、下工件。穿孔纸带是在带有特制穿孔附件的打字机或直接连到计算机上的纸带穿孔装置上做成的。纸带制造很少不出错,错误可能由编程、卡片穿孔或编码、纸带穿孔时的物理损害等形成。通常,必须要试走几次来排除错误,才能得到一个可用的工作纸带。

虽然纸带上的数据是自动进给的,但实际编程却是手工完成的,在编码纸带做好前,编程者经常要和一个计划人员或工艺工程师一起工作,选择合适的数控机床,决定加工材料,计算切削速度和进给速度,决定所需刀具类型,仔细阅读零件图上尺寸,定下合适的程序开始的零参考点,然后写出程序清单,其上记载有描述加工顺序的编码数控指令,机床按顺序加工工件到图样要求。

控制单元接受和储存编码数据,直至形成一个完整的信息程序块,然后解释数控指令,并引导机床得到所需运动。

为更好理解控制单元的作用,可将它与拨号电话进行比较,即每拨一个数字,就储存一个,当整个数字拨好后,电话就被激活,也就完成了呼叫。

装在控制单元里的纸带阅读机,通过其内的硅光二极管,检测到穿过移动纸带上的孔漏

过的光线,将光束转变成电能,并通过放大来进一步加强信号,然后将信号送到控制单元里的寄存器,由它将动作信号传到机床驱动装置。

有些光电装置能以高达每秒1000个字节的速度阅读,这对保持机床连续动作是必须的,否则,在轮廓加工时,刀具可能在工件上产生划痕。阅读装置必须要能以比控制系统处理数据更快的速度来阅读数据程序块。

反馈装置是用在一些数控设备上的安全装置,它可连续补偿控制位置与机床运动滑台的实际位置之间的误差。装有这种直接反馈检查装置的数控机床有一个闭环系统装置。位置控制通过传感器实现,在实际工作时,记录下滑台的位置,并将这些信息送回控制单元。接受到的信号与纸带输入的信号相比较,它们之间的任何偏差都可得到纠正。

在另一个称为开环的系统中,机床仅由响应控制器命令的步进电动机驱动定位,工件的精度几乎完全取决于丝杠的精度和机床结构的刚度。有几个理由可以说明步进电机是一个自动化申请的非常有用的驱动装置。对于一件事物,它被不连续直流电压脉冲驱使,是来自数传计算机和其他的自动化的非常方便的输出控制系统。当多数是索引或其他的自动化申请所必备者的时候,步进电机对运行一个精确的有角进步也是理想的。因为控制系统不需要监听就提供特定的输出指令而且期待系统适当地反应的公开-环操作造成一个回应环,步进电机是理想的。一些工业的机械手使用高抬腿运步的马乘汽车驾驶员,而且步进电机是有用的在数字受约束的工作母机中。这些申请的大部分是公开-环 ,但是雇用回应环检测受到驱策的成份位置是可能的。环的一个分析者把真实的位置与需要的位置作比较,而且不同是考虑过的错误。那然后驾驶员能发行对步进电机的电脉冲,直到错误被减少对准零位。在这个系统中,没有信息反馈到控制单元的自矫正过程。出现误动作时,控制单元继续发出电脉冲。比如,一台数控铣床的工作台突然过载,阻力矩超过电机转矩时,将没有响应信号送回到控制器。因为,步进电机对载荷变化不敏感,所以许多数控系统设计允许电机停转。然而,尽管有可能损坏机床结构或机械传动系统,也有使用带有特高转矩步进电机的其他系统,此时,电动机有足够能力来应付系统中任何偶然事故。

最初的数控系统采用开环系统。在开、闭环两种系统中,闭环更精确,一般说来更昂贵。起初,因为原先传统的步进电动机的功率限制,开环系统几乎全部用于轻加工场合,最近出现的电液步进电动机已越来越多地用于较重的加工领域。