关于数控车床编程外文文献翻译、中英文翻译、外文翻译

英文原文

On the NC lathe

CNC machine tool numerical control machine tools (Computer numerical control machine tools) abbreviation, is provided with a program control system of automatic machine tools. The logic control system can deal with the control code or other symbolic instruction specified program, and decoding the digital code, said information carrier, through the numerical control device input. After processing by CNC device control signals, control the machine movements, by drawing the shape and size requirements, will be automatically processed by the parts.

Features: CNC machine tool operation and monitoring of all completed in the numerical

control unit, it is the brain of CNC machine tools. Compared with the general machine tools, CNC machine tools has the following characteristics:

● the processing object adaptability, adapt to the characteristics of mold products such as a single production, provide the appropriate processing method for die and mould manufacturing; ● high machining accuracy, processing with stable quality; ● can coordinate linkage, processing complex shape parts;

● machining parts change, only need to change the program, can save the preparation time of production;

● the machine itself high precision, rigidity, can choose the amount of processing good, high productivity (3~5 times as common machine);

The machine is a high degree of automation, reducing labor intensity;

● conducive to the production management modernization. The use of CNC machine tools and the standard code of digital information processing, information transmission, the use of computer control method, has laid the foundation for the integration of computer aided design, manufacturing and management;

● on the operators of higher quality, higher demands for the repair of the technical staff;

● high reliability.

Composition: CNC machine tools in general by the input medium, man-machine interactive equipment, CNC equipment, feed servo drive system, spindle servo drive system, the auxiliary control device, feedback apparatus and adaptive control device etc.. [4] in NC machining, NC milling processing is the most complex, need to solve most problems. NC programming of NC line in addition to CNC milling, cutting, CNC EDM, CNC lathe, CNC grinding, each with its own characteristics, servo system is the role of the motion signal is converted into the machine moving parts from the numerical control device of pulse. Concrete has the following parts: the structure of CNC machine tools.

Driver: he is driving parts of CNC machine tools, actuator, including spindle drive unit, feeding unit, spindle motor and feed motor. He through the electric or electro-hydraulic servo system to realize the spindle and feed drive under the control of numerical control device. When several feed linkage, can complete the positioning, processing line, plane curve and space curve. The main performance (1) the main dimensions. (2) the spindle system. (3) feed system. (4) tool system.

(5) electrical. Including the main motor, servo motor specifications and power etc.. (6) cooling system. Including the cooling capacity, cooling pump output. (7) dimensions. Expressed as length * width * height.

Development trend of CNC lathe:

High speed, precision, complex, intelligent and green is the general trend in the development of CNC machine tool technology, in recent years, made gratifying achievements in practicality and industrialization. Mainly in the:

1 machine tool composite technology to further expand with the CNC machine tool technology, composite processing technology matures, including milling - car compound, car milling

compound, car - boring - drill - gear cutting compound, composite grinding, forming, composite processing, precision and efficiency of machining is greatly improved. \

processing factory\the development of compound processing machine tool is the trend of diversified.

Intelligent technology 2 CNC machine tools have a new breakthrough, in the performance of NC system has been reflected more. Such as: automatically adjust the interference anti-collision function, after the power of workpiece automatically exit safety power-off protection function, machining parts detection and automatic compensation function of learning, high precision

machining parts intelligent parameter selection function, process automatic elimination of machine vibration functions into the practical stage, intelligent upgrade the function of machine and quality.

The 3 robots enable flexible combination of flexible combination of higher efficiency of robot and the host are widely used, make flexible line more flexible, extending the function, flexible line shorten further, more efficient. Robot and machining center, milling composite machine, grinder, gear processing machine tool, tool grinding machine, electric machine, sawing machine, punching machine, laser cutting machine, water cutting machine etc. various forms of flexible unit and flexible production line has already begun the application.

4 precision machining technology has the machining precision of CNC metal cutting machine tools from the yarn in the original (0.01mm) up to micron level (0.001mm), some varieties has reached about 0.05 μ M. Micro cutting and grinding machining of ultra precision CNC machine tools, precision can reach about 0.05 μ m, shape precision can reach about 0.01 μ M. Special processing precision by using optical, electrical, chemical, energy can reach nanometer level (0.001 μ m). By optimizing the design of machine tool structure, machine tool parts of ultra precision machining and precision assembly, using high precision closed loop control and

temperature, vibration and other dynamic error compensation technology, improve the geometric accuracy of machine tool processing, reduce the shape of error, surface roughness, and into the submicron, nano super finishing ti

The 5 functional component to improve the performance of functional components are at a high speed, high precision, high power and intelligent direction, and obtain the mature application. A full digital AC servo motor and drive device, high technology content of the electric spindle, linear motor, torque motor, linear motion components with high performance, application of high precision spindle unit and other function parts, greatly improving the technical level of CNC machine tools.

The feed drive system of CNC lathe: Effect of feed drive system,

The feed drive system of CNC machine tools will be received pulse command issued by the numerical control system, and the amplification and conversion machine movements carry the expected movement.

Two, the feeding transmission system requirements

In order to guarantee the machining accuracy of NC machine tool is high, the feed drive system of transmission accuracy, sensitivity high (fast response), stable work, high stiffness and friction and inertia small, service life, and can remove the transmission gap. Category three, feed drive system 1, stepping motor servo system Generally used for NC machine tools. 2, DC servo motor servo system

Power is stable, but because of the brush, the wear resulting in use need to change. Generally used for middle-grade CNC machine tools. 3, AC servo motor servo system

The application is extremely widespread, mainly used in high-end CNC machine tools. 4, the linear motor servo system

No intermediate transmission chain, high precision, the feed speed, no length limit; but the poor heat dissipation, protection requirements are particularly high, mainly used for high-speed machine.

Driving component four, feed system 1, the ball screw nut pair

NC machining, the rotary motion into linear motion, so the use of screw nut transmission

mechanism. NC machine tools are commonly used on the ball screw, as shown in Figure 1-25, it can be a sliding friction into rolling friction, meet the basic requirements of the feed system to reduce friction. The transmission side of high efficiency, small friction, and can eliminate the gap, no reverse air travel; but the manufacturing cost is high, can not lock, size is not too big, generally used for linear feed in small CNC machine tool. 2, rotary table

In order to expand the scope of the process of NC machine tools, CNC machine tools in addition to make linear feed along the X, Y, Z three coordinate axes, often also need a circumferential feed movement around Y or Z axis. Circular feed motion of CNC machine tools in general by the rotary table to realize, for machining center, rotary table has become an indispensable part of. Rotary table of commonly used CNC machine tools in the indexing table and NC rotary table. (1) indexing table

Indexing table can only finish dividing movement, not circular feed, it is in accordance with the instructions in the NC system, when indexing will work together with the workpiece rotation angle. When indexing can also use manual indexing. Provisions of indexing table is generally only rotary angle (such as 90, 60 and 45 degree). (2) NC rotary table

NC rotary table appearance similar to the indexing table, but the internal structure and function is not the same. The main function of the NC rotary table is based on the numerical control device sends command pulse signal, complete circumferential feed movement, various arc processing and surface processing, it can also be graduation work. 3, guide

Rail is an important part of feed drive system, is one of the basic elements of the structure of machine tool, rigidity, precision and accuracy of NC machine tool which determines to a large extent retention. At present, guide the NC machine tool are sliding rail, rolling guideway and hydrostatic guideway. (1) sliding guide

Sliding guide rail has the advantages of simple structure, easy manufacture, good stiffness, vibration resistance and high performance, widely used in CNC machine tools, the use of most metal plastic form, known as the plastic guide rail, as shown in figure 1-26.

On characteristics of the plastic sliding guide: friction characteristic is good, good wear resistance, stable movement, good manufacturability, low speed. (2) rolling guide

Rolling guide is placed in the rail surface between the ball, roller or needle roller, roller, the rolling friction instead of sliding surface of the guide rail between wipe.

Rolling guide rail and the sliding rail, high sensitivity, small friction coefficient, and the dynamic, static friction coefficient is very small, so the motion is uniform, especially in the low speed movement, the stick-slip phenomenon is not easy to occur; high positioning accuracy,

repeatability positioning accuracy is up to 0.2 μ m; traction force is small, wear small, portable in movement; good precision, long service life. But the vibration of rolling guide, high requirements on protection, complicated structure, difficult manufacture, high cost.

Automatic tool changer:

One, the function of automatic tool changer

Automatic tool changing device can help save the auxiliary time of CNC machine tools, and meet in an installation completed procedure, step processing requirements. Two, on the requirement of automatic tool changer

Numerical control machine tool for automatic tool changer requirement is: tool change quickly, time is short, high repetitive positioning accuracy, tool storage capacity is sufficient, small occupation space, stable and reliable work. Three, change the knife form 1, rotary cutter replacement

Its structure is similar to the ordinary lathe turret saddle, according to the processing of different objects can be designed into square or six angle form, consists of the NC system sends out the instruction to the rotary cutter.

2, the replacement of the spindle head tool change

The spindle head pre-loaded required tools, in order to machining position, the main motor is switched on, drives the cutter to rotate. The advantage of this method is that eliminates the need for automatic clamping, cutting tool, clamping and cutting tool moving and a series of complex operation, reduce tool change time, improve The ATC reliability. 3, the use of changing tool

The processing required tools are respectively arranged in the standard tool, adjust the size of the machine after certain way add to the knife, the exchange device from the knife and the spindle take knife switch.

Four, the tool switching device

Automatic tool change device, device for knife library and the main shaft transmission and

handling tool for tool exchange device. Tool exchange often have two kinds: mechanical hand tool exchange and by relative motion of knife and machine tool spindle exchange tool (knife to spindle for

The knife or the spindle motion to the knife knife tool change position), the mechanical hand tool change is most common. Five, the knife

The knife is one of the most important parts in automatic tool changer, have great influence on the overall design of NC machine tool and its capacity, layout and structure. 1, the capacity of the tool storage

A number of knife inventory cutters, generally depending on the processing requirements. The capacity of small knife, can not meet the processing needs; capacity is too large, will make the knife database size, covers an area of large, tool selection process for a long time, and the knife library utilization rate is low, the structure is too complex, causing great waste. 2, the knife type Generally, the chain disc and drum type knife several.

Disc cutter tool was circular arrangement, low utilization of space, size is not large but simple structure.

Chain magazine compact structure, large capacity, link shape can also be random bed made of various forms and flexible layout, but also will change the cutter location prominent for tool change, widely used.

Drum type or lattice type knife, covers an area of small, compact structure, large capacity, but cutter selection, tool movements are complicated, for centralized knife system for FMS. 3, tool selection

Often order tool selection and random selection tool two.

The order of tool selection is before processing, the processing required tools to process sequence of insert knife knife, order not wrong, processing adjust knife in order. The work piece changes, the need to reset the tool sequence, the operation is simple, and the processing tool with a workpiece can not be repeated use.

A knife is the cutting tool has its own code, optional and can be repeatedly used in processing, also do not put in the fixed knife, knife, the knife is convenient.

Technology file is the guiding file workers during processing, process scheme is reasonable, not only affect the efficiency of NC machining, and will directly affect the machining quality. Therefore, before NC programming, NC machining process follows the process of certain

principles and combined with the characteristics of CNC lathe seriously and develop in detail the good parts.

In the CNC lathe processing parts, should according to the principle of dividing process concentrated, in a fixture as far as possible to complete the most or even all of the surface processing. Part positioning, according to the structure of different shapes, usually cylindrical, face or end clamping, and strive to design basis, process reference and programming the unification datum.

The main contents are: analysis of NC machining technology of part drawings, clear processing content; determination method, workpiece on lathe the surface processing sequence and tool feed line and cutting tools, fixtures and cutting the amount of choice. Analysis, part drawing process

In the machining process planning of parts, first of all to carry on in-depth analysis to the processing object. For NC turning process should consider the following aspects: 1 reading part drawing, analysis of geometric conditions of part contour

In turning process of manual programming, to calculate each node coordinates; in automatic

programming, to define the components outline all geometric elements. Therefore, in the analysis of parts should pay attention to:

Parts of the map is missing a dimension, the geometric conditions are not sufficient to constitute the part outline, influence;

Map location map parts of the ambiguity or dimension is not clear, so that the program can't start; The part drawing geometry given is not reasonable, resulting in mathematical difficulties. The part drawing dimensioning methods should adapt to the characteristics of CNC lathe processing, should size or directly given coordinate dimension with the same standard. 2 dimensional accuracy requirements

Analysis of the pattern of parts size precision requirements, to determine whether achieve the turning process, and determine the process method to control the dimension precision.

In the analysis process, but also can convert some dimensions such as size, incremental and

absolute size and dimension chain calculation. In the use of NC lathe turning parts, average value of components often required size and maximum and minimum limit of size size as the basis of programming.

3 shape and position accuracy requirements

Pattern of parts tolerance of shape and location given is important foundation to ensure the parts precision. When machining parts, to determine the location reference and measurement reference according to the requirements, can also carry out some technical processing according to the special needs of CNC lathe parts, in order to control effectively the shape and position accuracy.

4 requirements of surface roughness

Surface roughness is an important requirement of micro precision parts of the surface, but also the reasonable selection of NC lathe, cutting tools and cutting the amount determined on the basis of. 5 material and heat treatment requirements

The part drawing on material and heat treatment given requirements, is the choice of cutter, CNC lathe, cutting the amount determined on the basis of model. Determination of two and fixture, clamping scheme selection Division 1.

(1) according to the tool used by the process division can improve machining efficiency. (2) can keep the NC lathe machining according to the rough, finishing process division adopted this approach accuracy.

The 2 part is determined and the fixture clamping scheme selection

The CNC lathe parts mounting method is the same with the ordinary lathe, universal fixture

should try to choose the existing clamping, and attention should be paid to reduce clamping times, as far as possible in one clamping parts can put all to processing surface processing. Datum location should be coincident with the design reference, in order to reduce the positioning error effect on the dimensional accuracy.

CNC lathe with chuck with three jaws to clamp workpiece; shaft parts can also be used to support the tailstock center. Due to the NC lathe spindle speed is very high, for the convenience of the workpiece clamping, the use of hydraulic high-speed power chuck, because it is in the production plant has passed the strict balanced, with a high speed (the speed limit is 4000 ~ 6000rpm), high clamping force (the maximum force is 2000 ~ 8000N), high precision, convenient adjusting claw, a through hole long service life, etc.. By adjusting the pressure of oil cylinder, which can change the clamping force, the special needs of holding various thin-walled workpiece deformation and easy to meet.

Deformation of slender shaft processing to reduce stress, improve the machining accuracy, as well as in processing the shaft with hole workpiece inner hole, the hydraulic automatic centering central frame, the centering precision can reach 0.03 mm. Three, determine the processing order and feed route Determination of 1 processing sequence

In the process of NC machine tool, as the processing object is complicated, especially the shape and position of the myriads of changes curve, with the influence of different materials, different from that of the bulk and other factors, in the formulation of the processing sequence of specific parts, should make a concrete analysis and distinction, flexible processing. Only in this way, can the processing order of the rational, so as to achieve excellent quality, high efficiency and low cost objective.

(1) the coarse to fine

In order to improve production efficiency and ensure the precision parts processing quality, in the cutting process, should arrange the roughing process, in a relatively short period of time, the

finishing before machining allowance amount of removed, at the same time as much as possible to meet the precision machining allowance uniformity requirements.

When the roughing process arrangement is finished, and then arrange the semi-finish machining and finish machining for the knife after the. Among them, arrange the semi-finishing aims, when after the rough machining allowance of uniformity can not meet the precision requirement, can arrange the semi-finish machining as a transitional process, in order to make the finishing allowance is small and uniform.

In the arrangement of a knife or blade finish machining process of the part, the final contour should be the last knife and continuous processing. At this time, the cutting tool and cutter

location to consider appropriate, try not to arrange the cut and cut out or tool change and pause in a continuous contour, so as to avoid sudden changes of cutting force caused by elastic deformation, resulting in smooth connection defects, surface scratch shape mutation or retention tool mark profile.

(2) to nearly far after processing, reduce air travel time

Here said the far and near, is according to the processing site relative to the size of the knife point distance. In general, especially in the rough, usually arranged from near the site of the first processing tool, tool bit far from site after processing, in order to shorten tool moving distance, reduce air travel time. For turning, the first after the far past helps maintain the rough or semi-finished parts of the rigid, improve the cutting condition. (3) and cross

On both the inner surface (inner type cavity), and outer surface of machined parts, the processing sequence arrangement, should be done before and after surface rough machining, inner and outer surface finishing. Must not be parts of a portion of the surface (the inner or outer surface) after machining, processing and other surface (inner or outer surface). (4) surface of first principles

Surface is used as a fine benchmark priority should be processed, because the surface of locating datum is more precise, clamping error is smaller. For example, shaft parts processing, always first machining center hole, and then to the center hole for precision machining surface and surface. The principle is not immutable and frozen, for some special cases, you need to take a flexible scheme.

Determination of processing feed line 2

The feed line is the tool relative to the workpiece in the whole movement process, it not only

includes the steps of content, but also reflect the step sequence. One of the feed line is the basis of programming.

Determine the processing route must keep the size precision and surface quality of machining parts, then consider the numerical calculation is simple, knife route as short as possible, higher efficiency. Because of the feed line finishing is basically along the contour sequence, therefore the determination of feed line focus is to determine the feed line rough machining and air travel. The following will analyze:

(1) the relationship between processing route and machining allowance

In the CNC lathe is not to popularize the use of conditions, the general should be a roughcast margin too much, especially with forging, casting hard layer cushion placed in ordinary lathe. If must use NC lathe machining, should pay attention to the flexible program. The first cutting processing must arrange some subroutine to margin too much site. (2) the tool cut, cut out

The processing of CNC machine tools, to arrange the tool cut, cut out the route, the tangent direction to make the tool along the outline of the cut, cut out. (3) to determine the shortest route for empty

Determine the shortest tool path, in addition to rely on a lot of practical experience, should be good at analysis, if necessary, supplemented by some simple calculations. (4) determine the cutting feed shortest

Cutting feed route is short, can effectively improve the production efficiency, reduce the tool wear. In the cutting feed route arrangement the rough or semi-finished, it shall also take into account to be rigid and processing parts processing technology requirements, do not care for this and lose that.

Four, to determine the cutting parameters

CNC programming, the programmer must determine the cutting parameters of each process, and instructions in the form of written procedures. Cutting parameters including spindle speed, depth of cut and feed speed. For the different processing methods, selection of cutting parameters for different needs. Principle of selection of cutting parameters is: to ensure the accuracy and surface roughness of the parts processing, give full play to the tool cutting performance, guarantee a reasonable tool life and give full play to the performance of the machine tool, to maximize the productivity, reduce the cost of. To determine the 1 spindle speed (1) determine the spindle speed of light car

Spindle speed should be based on the allowable cutting speed and workpiece diameter selection, the calculation formula is as follows N=1000v/ (d)

Type V -- the cutting speed (M / min), determined by the tool life.

N -- the spindle speed (R / min);

D -- or the diameter of cutter and workpiece diameter (mm).

Spindle speed calculation n finally depends on the machine specifications selecting machine or close to the speed of.

(2) the car threaded spindle speed

In thread cutting, the lathe spindle speed will be thread pitch (or lead) factors affecting size, driving motor movements frequency characteristics and thread interpolation operation speed, the different NC systems, recommended the spindle speed range of different options. Spindle speed as most ordinary lathe CNC system recommended threading: N ≤ 1200/p-K

Type P -- pitch or lead the thread (mm); K -- the insurance factor, usually taken as 80; N -- the spindle speed, rpm. To determine the 2 feed speed

The feed velocity is an important parameter in the CNC machine tool cutting, mainly according to the machining accuracy and surface roughness value selection of parts and tool, workpiece

material properties. The maximum speed limit by the performance of machine tool stiffness and feed system.

To determine the feed speed is the principle:

(1) when the workpiece quality requirements can be guaranteed, in order to improve the production efficiency, can choose the higher feed rate. 100 ~ 200mm / min range selection. (2) in cutting, machining deep hole or processing of high-speed steel cutting tool, should choose a lower feeding rate, generally in the 20 ~ 50mm / min range selection.

(3) when processing high precision and surface roughness values is small, the feed rate should be smaller, the range of 20~50mm/min selection.

(4) the tool to air travel, especially to zero distance, can be set to the highest feed speed setting of the machine tool CNC system. To determine the depth of the 3

The cutting depth was decided according to machine tool, workpiece and cutting tool rigidity, stiffness in the permit conditions, should as far as possible back an amount equal to the machining allowance of the workpiece, thus reducing the feeding times, improve production efficiency. In order to guarantee the machining surface can leave a little machining allowance, generally 0.2 ~ 0.5mm.

The cutting parameters (α P, F, VC) choice is whether reasonable, to exert the potential and the cutting performance of machine tool, to realize high quality, high yield, low cost and safe

operation plays a very important role. The following specific selection principle of turning amount (1) thick, think first of choosing a large depth of cut of α P, then choose a larger amount of feed F, and finally to determine an appropriate cutting speed VC, increasing the depth of α P can reduce the number of feed, increase feed f to cut off. Therefore, according to the above principles to choose rough cutting parameters to improve production efficiency, reduce cutter consumption reduce processing cost is favorabl

(2) refined, high machining accuracy, surface roughness requirement is small, the machining allowance is small and uniform, the choice of small (but not too small) and the cutting depth and feed rate, cutting performance and tool material selection and reasonable geometric parameters, so as to improve the cutting speed VC possible.

(3) in the arrangement of coarse, fine cutting dosage, attention should be paid to the allowed range of cutting machine specifications given. For CNC machine tools, spindle adopts AC frequency conversion speed, due to spindle in low speed when the torque reduction, especially should pay attention to the choice of cutting parameters at.

In short, specific numerical cutting amount should be based on the performance of a machine tool, the manual and combining the practical experience is determined by simulation method. At the same time, the spindle speed, cutting depth and feed rate of three can adapt to each other, to form the optimal cutting parameters.

中文原文

关于数控车床

数控机床是数字控制机床（Computer numerical control machine tools）的简称，是一种装有程序控制系统的自动化机床。该控制系统能够逻辑地处理具有控制编码或其他符号指令规定的程序，并将其译码，用代码化的数字表示，通过信息载体输入数控装置。经运算处理由数控装置发出各种控制信号，控制机床的动作，按图纸要求的形状和尺寸，自动地将零件加工出来。

特点：数控机床的操作和监控全部在这个数控单元中完成，它是数控机床的大脑。与普通机床相比，数控机床有如下特点：

●对加工对象的适应性强，适应模具等产品单件生产的特点，为模具的制造提供了合适的加工方法；

●加工精度高，具有稳定的加工质量；

●可进行多坐标的联动，能加工形状复杂的零件；

●加工零件改变时，一般只需要更改数控程序，可节省生产准备时间；

●机床本身的精度高、刚性大，可选择有利的加工用量，生产率高（一般为普通机床的3~5倍）；

●机床自动化程度高，可以减轻劳动强度；

●有利于生产管理的现代化。数控机床使用数字信息与标准代码处理、传递信息，使用了计算机控制方法，为计算机辅助设计、制造及管理一体化奠定了基础； ●对操作人员的素质要求较高，对维修人员的技术要求更高； ● 可靠性高。

组成：数控机床一般由输入介质、人机交互设备、计算机数控装置、进给伺服驱动系统、主轴伺服驱动系统、辅助控制装置、反馈装置和适应控制装置等部分组成。[4]在数控加工中，数控铣削加工最为复杂，需解决的问题也最多。除数控铣削加工之外的数控线切割、数控电火花成型、数控车削、数控磨削等的数控编程各有其特点，伺服系统的作用是把来自数控装置的脉冲信号转换成机床移动部件的运动。具体有以下部分构成：数控机床的构造。

驱动装置：他是数控机床执行机构的驱动部件，包括主轴驱动单元、进给单元、主轴电机及进给电机等。他在数控装置的控制下通过电气或电液伺服系统实现主轴和进给驱动。当几个进给联动时，可以完成定位、直线、平面曲线和空间曲线的加工。 主要性能

(1)主要规格尺寸。 (2)主轴系统。 (3)进给系统。 (4)刀具系统。

(5)电气。包括主电动机、伺服电动机的规格型号和功率等。 (6)冷却系统。包括冷却箱容量、冷却泵输出量等。 (7)外形尺寸。表示为长×宽×高。

数控车床的发展趋势：

高速、精密、复合、智能和绿色是数控机床技术发展的总趋势，近几年来，在实用化和产业化等方面取得可喜成绩。主要表现在：

1． 机床复合技术进一步扩展随着数控机床技术进步，复合加工技术日趋成熟，包括铣-车复合、车铣复合、车-镗-钻-齿轮加工等复合，车磨复合，成形复合加工、特种复合加工等，复合加工的精度和效率大大提高。“一台机床就是一个加工厂”、“一次装卡，完全加工”等

理念正在被更多人接受，复合加工机床发展正呈现多样化的态势。

2．数控机床的智能化技术有新的突破，在数控系统的性能上得到了较多体现。如：自动调整干涉防碰撞功能、断电后工件自动退出安全区断电保护功能、加工零件检测和自动补偿学习功能、高精度加工零件智能化参数选用功能、加工过程自动消除机床震动等功能进入了实用化阶段，智能化提升了机床的功能和品质。

3．机器人使柔性化组合效率更高机器人与主机的柔性化组合得到广泛应用，使得柔性线更加灵活、功能进一步扩展、柔性线进一步缩短、效率更高。机器人与加工中心、车铣复合机床、磨床、齿轮加工机床、工具磨床、电加工机床、锯床、冲压机床、激光加工机床、水切割机床等组成多种形式的柔性单元和柔性生产线已经开始应用。

4．精密加工技术有了新进展数控金切机床的加工精度已从原来的丝级（0.01mm）提升到微米级（0.001mm），有些品种已达到0.05μm左右。超精密数控机床的微细切削和磨削加工，精度可稳定达到0.05μm左右，形状精度可达0.01μm左右。采用光、电、化学等能源的特种加工精度可达到纳米级（0.001μm）。通过机床结构设计优化、机床零部件的超精加工和精密装配、采用高精度的全闭环控制及温度、振动等动态误差补偿技术，提高机床加工的几何精度，降低形位误差、表面粗糙度等，从而进入亚微米、纳米级超精加工时代。 5．功能部件性能不断提高功能部件不断向高速度、高精度、大功率和智能化方向发展，并取得成熟的应用。全数字交流伺服电机和驱动装置，高技术含量的电主轴、力矩电机、直线电机，高性能的直线滚动组件，高精度主轴单元等功能部件推广应用，极大的提高数控机床的技术水平。

数控车床的进给传动系统： 一、进给传动系统作用

数控机床的进给传动系统负责接受数控系统发出的脉冲指令，并经放大和转换后驱动机床运动执行件实现预期的运动。 二、对进给传动系统的要求

为保证数控机床高的加工精度，要求其进给传动系统有高的传动精度、高的灵敏度（响应速度快）、工作稳定、有高的构件刚度及使用寿命、小的摩擦及运动惯量，并能清除传动间隙。

三、进给传动系统种类

1、步进伺服电机伺服进给系统 一般用于经济型数控机床。 2、直流伺服电机伺服进给系统

功率稳定，但因采用电刷，其磨损导致在使用中需进行更换。一般用于中档数控机床。 3、交流伺服电机伺服进给系统

应用极为普遍，主要用于中高档数控机床。 4、直线电机伺服进给系统

无中间传动链，精度高，进给快，无长度限制；但散热差，防护要求特别高，主要用于高速机床。

四、进给系统传动部件 1、滚珠丝杠螺母副

数控加工时，需将旋转运动转变成直线运动，故采用丝杠螺母传动机构。数控机床上一般采用滚珠丝杠，如图1-25所示，它可将滑动摩擦变为滚动摩擦，满足进给系统减少摩擦的基本要求。该传动副传动效率高，摩擦力小，并可消除间隙，无反向空行程；但制造成本高，不能自锁，尺寸亦不能太大，一般用于中小型数控机床的直线进给。 2、回转工作台

为了扩大数控机床的工艺范围，数控机床除了沿X、Y、Z三个坐标轴作直线进给外,往往还需要有绕Y或Z轴的圆周进给运动。数控机床的圆周进给运动一般由回转工作台来实现，对于加工中心,回转工作台已成为一个不可缺少的部件。 数控机床中常用的回转工作台有分度工作台和数控回转工作台。

（1）分度工作台

分度工作台只能完成分度运动,不能实现圆周进给，它是按照数控系统的指令，在需要分度时将工作台连同工件回转一定的角度。分度时也可以采用手动分度。分度工作台一般只能回转规定的角度(如90、60和45度等)。 （2）数控回转工作台

数控回转工作台外观上与分度工作台相似，但内部结构和功用大不相同。数控回转工作台的主要作用是根据数控装置发出的指令脉冲信号，完成圆周进给运动，进行各种圆弧加工或曲面加工，它也可以进行分度工作。 3、导轨

导轨是进给传动系统的重要环节，是机床基本结构的要素之一，它在很大程度上决定数控机床的刚度、精度与精度保持性。目前，数控机床上的导轨形式主要有滑动导轨、滚动导轨和液体静压导轨等。 （1）滑动导轨

滑动导轨具有结构简单、制造方便、刚度好、抗振性高等优点,在数控机床上应用广泛，目前多数使用金属对塑料形式,称为贴塑导轨，如图1-26所示。

贴塑滑动导轨的特点：摩擦特性好、耐磨性好、运动平稳、工艺性好、速度较低。 （2）滚动导轨

滚动导轨是在导轨面之间放置滚珠、滚柱或滚针等滚动体，使导轨面之间为滚动摩擦而不是滑动擦擦。

滚动导轨与滑动导轨相比，其灵敏度高，摩擦系数小，且动、静摩擦系数相差很小，因而运动均匀，尤其是在低速移动时，不易出现爬行现象；定位精度高，重复定位精度可达0.2μm；牵引力小，移动轻便；磨损小，精度保持性好，使用寿命长。但滚动导轨的抗振性差，对防护要求高,结构复杂，制造困难，成本高。

自动换刀装置：

一、自动换刀装置的作用

自动换刀装置可帮助数控机床节省辅助时间，并满足在一次安装中完成多工序、工步加工要求。

二、对自动换刀装置的要求

数控机床对自动换刀装置的要求是：换刀迅速、时间短，重复定位精度高，刀具储存量足够，所占空间位置小，工作稳定可靠。 三、换刀形式

1、回转刀架换刀

其结构类似普通车床上回转刀架，根据加工对象不同可设计成四方或六角形式，由数控系统发出指令进行回转换刀。 2、更换主轴头换刀

各主轴头预先装好所需刀具，依次转至加工位置，接通主运动，带动刀具旋转。该方式的优点是省去了自动松夹、装卸刀具、夹紧及刀具搬动等一系列复杂操作，缩短了换刀时间，提高

了换刀可靠性。

3、使用刀库换刀

将加工中所需刀具分别装于标准刀柄，在机外进行尺寸调整之后按一定方式放入刀库，由交换装置从刀库和主轴上取刀交换。 四、刀具交换装置

自动换刀装置中，实现刀库与主轴间传递和装卸刀具的装置为刀具交换装置。刀具交换方式常有两种：采用机械手交换刀具和由刀库与机床主轴的相对运动交换刀具（刀库移至主轴处换

刀或主轴运动到刀库换刀位置换刀）,其中以机械手换刀最为常见。 五、刀库

刀库是自动换刀装置中最主要的部件之一，其容量、布局及具体结构对数控机床的总体设计有很大影响。 1、刀库容量

指刀库存放刀具的数量，一般根据加工工艺要求而定。刀库容量小，不能满足加工需要；容量过大，又会使刀库尺寸大，占地面积大，选刀过程时间长，且刀库利用率低，结构过于复杂，造成很大浪费。2、刀库类型 一般有盘式、链式及鼓轮式刀库几种。

盘式刀库 刀具呈环行排列，空间利用率低，容量不大但结构简单。

链式刀库 结构紧凑，容量大，链环的形状也可随机床布局制成各种形式而灵活多变，还可将换刀位突出以便于换刀，应用较为广泛。

鼓轮式或格子式刀库, 占地小，结构紧凑，容量大，但选刀、取刀动作复杂，多用于FMS的集中供刀系统。 3、选刀方式

常有顺序选刀和任意选刀两种。

顺序选刀是在加工前，将加工所需刀具依工艺次序插入刀库刀套中，顺序不能有差错，加工时按顺序调刀。工件变更时，需重调刀具顺序，操作烦琐，且加工同一工件中刀具不能重复使用。

任意选刀是刀具均有自己的代码，加工中任选且可重复使用，也不用放于固定刀座，装刀、选刀都较方便。

工艺文件是工人加工时的指导性文件，工艺方案的是否合理，不仅会影响数控加工的效率，而且将直接影响零件加工的质量。因此，在数控车削程序编制之前，遵循一定的工艺原则并结合数控车床的特点认真而详细地制定好零件的数控车削加工工艺。

在数控车床上加工零件，应按工序集中的原则划分工序，在一次装夹中尽可能完成大部分甚至全部表面的加工。零件定位时，根据结构形状不同，通常选择外圆、端面或端面装夹，并力求设计基准、工艺基准和编程基准统一。

数控加工工艺的主要内容有：分析零件图纸，明确加工内容；确定工件在车床上的装夹方式、各表面的加工顺序和刀具进给路线以及刀具、夹具和切削用量的选择等。 一、零件图工艺分析

在设计零件的加工工艺规程时，首先要对加工对象进行深入分析。对于数控车削加工应考虑以下几方面：

1．阅读零件图，分析零件轮廓的几何条件

在车削加工中手工编程时，要计算每个节点坐标；在自动编程时，要对构成零件轮廓所有几何元素进行定义。因此在分析零件图时应注意：

零件图上是否漏掉某尺寸，使其几何条件不充分，影响到零件轮廓的构成； 零件图上的图线位置是否模糊或尺寸标注不清，使编程无法下手； 零件图上给定的几何条件是否不合理，造成数学处理困难。

零件图上尺寸标注方法应适应数控车床加工的特点，应以同一基准标注尺寸或直接给出坐标尺寸。

2．尺寸精度要求

分析零件图样尺寸精度的要求，以判断能否利用车削工艺达到，并确定控制尺寸精度的工艺方法。

在该项分析过程中，还可以同时进行一些尺寸的换算，如增量尺寸与绝对尺寸及尺寸链计算等。在利用数控车床车削零件时，常常对零件要求的尺寸取最大和最小极限尺寸的平均值作为编程的尺寸依据。

3．形状和位置精度的要求

零件图样上给定的形状和位置公差是保证零件精度的重要依据。加工时，要按照其要

求确定零件的定位基准和测量基准，还可以根据数控车床的特殊需要进行一些技术性处理，以便有效的控制零件的形状和位置精度。 4．表面粗糙度要求

表面粗糙度是保证零件表面微观精度的重要要求，也是合理选择数控车床、刀具及确定切削用量的依据。

5．材料与热处理要求

零件图样上给定的材料与热处理要求，是选择刀具、数控车床型号、确定切削用量的依据。

二、装夹方案的确定和夹具的选择 1．工序的划分

（1）按所用刀具划分工序 采用这种方式可提高车削加工的生产效率。 （2）按粗、精加工划分工序 采用这种方式可保持数控车削加工的精度。 2．确定零件装夹方案和夹具选择

数控车床上零件安装方法与普通车床一样，要尽量选用已有的通用夹具装夹，且应注意减少装夹次数，尽量做到在一次装夹中能把零件上所有要加工表面都加工出来。零件定位基准应尽量与设计基准重合，以减少定位误差对尺寸精度的影响。

数控车床多采用三爪卡盘夹持工件；轴类工件还可采用尾座顶尖支持工件。由于数控车床主轴转速极高，为便于工件夹紧，多采用液压高速动力卡盘，因它在生产厂已通过了严格平衡，具有高转速(极限转速可达4000～6000rpm)、高夹紧力(最大推拉力为2000～8000N)、高精度、调爪方便、通孔、使用寿命长等优点。通过调整油缸压力，可改变卡盘夹紧力，以满足夹持各种薄壁和易变形工件的特殊需要。

为减少细长轴加工时受力变形，提高加工精度，以及在加工带孔轴类工件内孔时，可采用液压自动定心中心架，其定心精度可达0.03㎜。 三、 加工顺序和进给路线的确定 1．加工顺序的确定

在数控机床加工过程中，由于加工对象复杂多样，特别是轮廓曲线的形状及位置千变万化，加上材料不同、批量不同等多方面因素的影响，在对具体零件制定加工顺序时，应该进行具体分析和区别对待，灵活处理。只有这样，才能使所制定的加工顺序合理，从而达到质量优、效率高和成本低的目的。 (1)先粗后精

为了提高生产效率并保证零件的精加工质量，在切削加工时，应先安排粗加工工序，在较短的时间内，将精加工前大量的加工余量去掉，同时尽量满足精加工的余量均匀性要求。

当粗加工工序安排完后，接着安排换刀后进行的半精加工和精加工。其中，安排半精加工的目的是，当粗加工后所留余量的均匀性满足不了精加工要求时，则可安排半精加工作为过渡性工序，以便使精加工余量小而均匀。

在安排可以一刀或多刀进行的精加工工序时，其零件的最终轮廓应由最后一刀连续加工而成。这时，加工刀具的进退刀位置要考虑妥当，尽量不要在连续的轮廓中安排切人和切出或换刀及停顿，以免因切削力突然变化而造成弹性变形，致使光滑连接轮廓上产生表面划伤、形状突变或滞留刀痕等疵病。 (2) 先近后远加工，减少空行程时间

这里所说的远与近，是按加工部位相对于对刀点的距离大小而言的。在一般情况下，特别是在粗加工时，通常安排离对刀点近的部位先加工，离对刀点远的部位后加工，以便缩短刀具移动距离，减少空行程时间。对于车削加工，先近后远有利于保持毛坯件或半成品件的刚性，改善其切削条件。 （3）内外交叉

对既有内表面（内型腔），又有外表面需加工的零件，安排加工顺序时，应先进行内外表面粗加工，后进行内外表面精加工。切不可将零件上一部分表面（外表面或内表面）加

工完毕后，再加工其他表面（内表面或外表面）。 （4）基面先行原则

用作精基准的表面应优先加工出来，因为定位基准的表面越精确，装夹误差就越小。例如轴类零件加工时，总是先加工中心孔，再以中心孔为精基准加工外圆表面和端面。 上述原则并不是一成不变的，对于某些特殊情况，则需要采取灵活可变的方案。 2．加工进给路线的确定

进给路线是刀具在整个加工工序中相对于工件的运动轨迹，它不但包括了工步的内容，而且也反映出工步的顺序。进给路线也是编程的依据之一。

加工路线的确定首先必须保持被加工零件的尺寸精度和表面质量，其次考虑数值计算简单、走刀路线尽量短、效率较高等。因精加工的进给路线基本上都是沿其零件轮廓顺序进行的，因此确定进给路线的工作重点是确定粗加工及空行程的进给路线。下面将具体分析：

（1）加工路线与加工余量的关系

在数控车床还未达到普及使用的条件下，一般应把毛坯件上过多的余量，特别是含有锻、铸硬皮层的余量安排在普通车床上加工。如必须用数控车床加工时，则要注意程序的灵活安排。安排一些子程序对余量过多的部位先作一定的切削加工。 （2）刀具的切入、切出

在数控机床上进行加工时，要安排好刀具的切入、切出路线，尽量使刀具沿轮廓的切线方向切入、切出。

（3）确定最短的空行程路线

确定最短的走刀路线，除了依靠大量的实践经验外，还应善于分析，必要时辅以一些简单计算。

（4）确定最短的切削进给路线

切削进给路线短，可有效地提高生产效率，降低刀具损耗等。在安排粗加工或半精加工的切削进给路线时，应同时兼顾到被加工零件的刚性及加工的工艺性等要求，不要顾此失彼。

四、切削用量的确定

数控编程时，编程人员必须确定每道工序的切削用量，并以指令的形式写入程序中。切削用量包括主轴转速、背吃刀量及进给速度等。对于不同的加工方法，需要选用不同的切削用量。切削用量的选择原则是：保证零件加工精度和表面粗糙度值，充分发挥刀具的切削性能，保证合理的刀具寿命并充分发挥机床的性能，最大限度提高生产率，降低成本。 1主轴转速的确定

（1）光车时主轴转速的确定

主轴转速应根据允许的切削速度和工件直径来选择，其计算公式为 n=1000v/(πd) 式中 v——切削速度(m／min)，由刀具的寿命决定。 n——主轴转速(r／min)；

d——工件直径或刀具直径(mm)。

计算的主轴转速n最后要根据机床说明书选取机床有的或较接近的转速而定。 （2）车螺纹时主轴转速

在切削螺纹时，车床的主轴转速将受到螺纹的螺距(或导程)大小、驱动电动机的升降频特性以及螺纹插补运算速度等多种因素影响，故对于不同的数控系统，推荐不同的主轴转速选择范围。如大多数普通型车床数控系统推荐车螺纹时的主轴转速如下： n≤1200/p-K 式中P——工件螺纹的螺距或导程(mm)； K——保险系数，一般取为80； n——主轴转速，rpm。 2.进给速度的确定

进给速度是数控机床切削用量中的重要参数，主要根据零件的加工精度和表面粗糙度值要求以及刀具、工件的材料性质选取。最大进给速度受机床刚度和进给系统的性能限制。 确定进给速度的原则是：

（1）当工件的质量要求能够得到保证时，为提高生产效率，可选择较高的进给速度。100～200mm／min范围内选取。

（2）在切断、加工深孔或用高速钢刀具加工时，宜选择较低的进给速度，一般在20～50mm／min范围内选取。

(3)当加工精度要求较高与表面粗糙度值要求较小时，进给速度应选小一些，20~50mm/min范围内选取。

(4)刀具空行程时，特别是远距离回零时,可以设定为该机床数控系统设定的最高进给速度。

3．背吃刀量的确定

背吃刀量根据机床、工件和刀具的刚度来决定，在刚度允许的条件下，应尽可能使背量等于工件的加工余量，这样可以减少进给次数，提高生产效率。为了保证加工表面可留少许精加工余量，一般为0.2～0.5mm。

以上切削用量（αp 、f、vc）选择是否合理，对于能否充分发挥机床潜力与刀具的切削性能，实现优质、高产、低成本和安全操作具有很重要的作用。车削用量的具体选择原则如下：

（1）粗车时，首先考虑选择一个尽可能大的背吃刀量αp，其次选择一个较大的进给量f，最后确定一个合适的切削速度vc，增大背吃刀量αp可使进给次数减少，增大进给量f有利于断削。因此，根据以上原则选择粗车切削用量对于提高生产效率，减少刀消耗降低加工成本是有利的。

（2）精车时，加工精度要求较高，表面粗糙度值要求较小，加工余量不大且均匀，此选择较小(但不太小)的背吃刀和进给量，并选用切削性能高的刀具材料和合理的几何参数，以尽可能的提高切削速度vc。

（3）在安排粗、精车削用量时，应注意机床说明书给定的允许切削用量范围。对于主轴采用交流变频调速的数控机床，，由于主轴在低转速时转矩降低，尤其应注意此时的切削用量选择。

总之．切削用量的具体数值应根据机床性能，相关的手册并结合实际经验用模拟方法确定。同时，使主轴转速、背吃刀量及进给速度三者能相互适应，以形成最佳切削用量。

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