In 1946 the first electronic accounting machine was born in the world, this indicated the humanity created has been possible to strengthen and partially to replace the mental labor the tool. It with the humanity these which in the agriculture, the industry society created only is strengthens the physical labor the tool to compare, got up the quantitive leap, entered the information society for the humanity to lay the foundation.

After 6 years, in 1952, computer technology applied to the engine bed , the first numerical control engine bed were born in US. From this time on, the traditional engine bed has had the archery target change. Since nearly half century, the numerical control system has experienced two stages and six generation of development.

The early computer operating speed is low, was not big to then science computation and the data processing influence, but could not adapt the engine bed real-time control request. The people can not but use numeral logic circuit "to build" to become an engine bed special purpose computer to take the numerical control system, is called the hardware connection numerical control (HARD-WIRED NC), Jian Chengwei numerical control (NC). Along with the primary device development, this stage has had been through repeatedly three generations, namely 1952 first generation of -- electron tube; 1959 second generation of -- transistor; 1965 third generation -- small scale integration electric circuit.

In 1970, the general minicomputer already appeared and the mass production. Thereupon transplants it takes the numerical control system the core part, from this time on entered the computer numerical control (CNC) the stage ("which should have computer in front of the general" two characters to abbreviate). In 1971, American INTEL Corporation in the world first time the computer two most cores part -- logic units and the controller, used the large scale integrated circuit technology integration on together the chip, called it the microprocessor (MICROPROCESSOR), also might be called the central processing element (to be called CPU).

The microprocessor is applied to 1974 in the numerical control system. This is because minicomputer function too strong, controlled an engine bed ability to have wealthily (therefore once uses in controlling the multi- Taiwan engine bed at that time, called it group control), was inferior to used the microprocessor economy to be reasonable. Moreover then small machine reliability was not ideal. The early microprocessor speed and the function although insufficiently are also high, but may solve through the multi-processor structure. Because the microprocessor is the general-purpose calculator core part, therefore still was called the computer numerical control.

  In 1990, PC machine (personal computer, domestic custom had called microcomputer) the performance has developed to the very high stage, may satisfiedly take the numerical control system core part the request. The numerical control system henceforth entered based on the PC stage.

In brief, the computer numerical control stage has also experienced three generations. Namely 1970 fourth generation of -- minicomputer; 1974 five dynasties -- microprocessor and 1990 sixth generation -- (overseas was called PC-BASED) based on PC.

Also must point out, although overseas already renamed as the computer numerical control (namely CNC).

　　Also must point out, although overseas already renamed as the computer numerical control (namely CNC), but our country still the custom called the numerical control (NC). Therefore we daily say "numerical control", the materially already was refers to "computer numerical control".

1.3.1 open style continues to, to develop based on the PC sixth generation of direction

The software and hardware resources has which based on PC are rich and so on the characteristic, the more numerical controls serial production factory can step onto this path. Uses PC machine to take at least its front end machine, processes the man-machine contact surface, the programming, the association

Question and so on net correspondence, undertakes the numerical control duty by the original system. PC machine has the friendly man-machine contact surface, will popularize to all numerical controls system. The long-distance communication, the long-distance diagnosis and the service will be more common.

1.3.2 approaches and the high accuracy development

This is adapts the engine bed to be high speed and the high accuracy direction need to develop.

1.3.3 develops to the intellectualized direction

Along with the artificial intelligence in the computer domain unceasing seepage and the development, the numerical control system intellectualized degree unceasingly will enhance.

(1) applies the adaptive control technology

The numerical control system can examine in the process some important information, and the automatic control system related parameter, achieves the improvement system running status the goal.

(2) introduces the expert system instruction processing

The skilled worker and expert's experience, the processing general rule and the special rule store in the system, take the craft parameter database as the strut, the establishment has the artificial intelligence the expert system.

(3) introduces the breakdown to diagnose the expert system

(4) intellectualized numeral servo drive

May through the automatic diagnosis load, but the automatic control parameter, causes the actuation system to obtain the best movement.

From on microscopic looked below that, the numerical control engine bed has the prominent superiority compared to the traditional engine bed, moreover these superiority come from the computer might which the numerical control system contains.

2.1.1 may process the traditional engine bed cannot process the curve, the curved surface and so on the complex components.

Because the computer has the excellent operation ability, may the instant accurately calculate each coordinate axis instant to be supposed the movement physiological load of exercise, therefore may turn round the synthesis complex curve or the curved surface.

2.1.2 may realize the processing automation, moreover is the flexible automation, thus the efficiency may enhance 3 ~ 7 times compared to the traditional engine bed.

Because the computer has the memory and the memory property, may the procedure which inputs remember and save, then the order which stipulated according to the procedure automatic carries out, thus realization automation. The numerical control engine bed so long as replaces a procedure, may realize another work piece processing automation, thus causes the single unit and the small batch of production can automate, therefore is called has realized "flexible automation".

2.1.3 processings components precision high, size dispersion degree small, makes the assembly to be easy, no longer needs "to make repairs".

2.1.4 may realize the multi- working procedures centralism, reduces the components in engine bed between frequent transporting.

2.1.5 has auto-alarm, the automatic monitoring, automatic compensation and so on the many kinds of autonomy function, thus may realize long time nobody to safeguard the processing.

2.1.6 advantage which derives by above five.

For example: Reduced worker's labor intensity, saved the labor force (a person to be possible to safeguard the multi- Taiwan engine bed), reduced the work clothes, reduced the new product trial manufacturing cycle and the production cycle, might to the market demand make rapid reaction and so on.

Above these superiority are the predecessor cannot imagine, is an extremely significant breakthrough. In addition, the engine bed numerical control carries out FMC (flexible manufacture unit), FMS (flexible manufacture system) as well as CIMS (computer integration manufacture system) and so on the enterprise becoming an information based society transformation foundation. The numerical control technology already became the manufacturing industry automation the core technology and the foundation technology.

From on macroscopic looked that, the industry developed country armed forces, the airplane weapon industry, in the end of the 70's, at the beginning of the 80's started the large-scale application numerical control engine bed. Its essence is, uses the information technology to the traditional industry (including the armed forces, airplane weapon industry) carries on the technological transformations. Except that uses outside the numerical control engine bed, FMC, FMS in the manufacture process, but also includes in the product development carries out CAD, CAE, CAM, the hypothesized manufacture as well as carries out MIS in the production management (management information system), CIMS and so on. As well as increases the information technology in its production product, including artificial intelligence and so on content. Because uses the information technology to the country foreign troops, the airplane weapon industry carries on the thorough transformation (to call it becoming an information based society), finally causes them the product in the international military goods and in the goods for civilian use market the competitive power greatly is the enhancement. But we in the information technology transformation tradition industry aspect compared to the developed country to fall behind approximately for 20 years. Like in our country engine bed capacity, numerical control engine bed proportion (numerical control rate) to 1995 only then 1.9%, but Japan has reached 20.8% in 1994, therefore every year has the massive mechanical and electrical products import. This also on from on macroscopic explained the engine bed numerical control transformation necessity.

In US, Japan and Germany and so on the developed country, their engine bed transforms took the new economical growth profession, thrives abundantly, is occupying the golden age. As a result of the engine bed as well as the technical unceasing progress, the engine bed transformation is "the eternal" topic. Our country's engine bed transformation industry, also enters from the old profession to by the numerical control technology primarily new profession. In US, Japan, Germany, have the broad market with the numerical control technological transformations engine bed and the production line, has formed the engine bed and the production line numerical control transformation new profession. In US, the engine bed transformation industry is called the engine bed regeneration (Remanufacturing) industry. Is engaged in the regeneration industry famous company to include: The Bertsche engineering firm, the ayton engine bed company, Devlieg-Bullavd (are valuable) serves the group, the US equipment company and so on. The American valuable company has set up the company in China. In Japan, the engine bed transformation industry is called the engine bed to reequip (Retrofitting) industry. Is engaged in the reequipment industry famous company to include: Big indentation project group, hillock three mechanical companies, thousand substitute fields labor machine company, wild  engineering firm, shore field engineering firm, mountain this engineering firm and so on.

The engine bed and the production line numerical control transformation main content has following several points:

First is extensively recovers the function, to the engine bed, the production line has the breakdown partially to carry on the diagnosis and the restoration;

    Second is NC, the addend reveals the installment on the ordinary engine bed, or adds the numerical control system, transforms the NC engine bed, the CNC engine bed;

    Third is renovates, for increases the precision, the efficiency and the automaticity, to the machinery, the electricity partially carries on renovates, reassembles the processing to the machine part, extensively recovers the precision; Does not satisfy the production request to it the CNC system to carry on the renewal by newest CNC;

    Fourth is the technology renews or the technical innovation, for enhances the performance or the scale, or in order to use the new craft, the new technology, carries on the big scale in the original foundation the technology to renew or the technical innovation, the great scope raises the level and the scale renewal transformation.    The new electrical system transforms after, how carries on the debugging as well as the determination reasonable approval standard, also is the technology preparatory work important link. The debugging work involves the machinery, the hydraulic pressure, the electricity, the control, and so on, therefore must carry on by the project person in charge, other personnel coordinate. The debugging step may conform to simplicity to numerous, from infancy to maturity, carries on from outside to in, after also may the partial overall situation, after first the subsystem the

3.3.1 reduced investment costs, the date of delivery are short

　　With purchases the new engine bed to compare, may save 60% ~ 80% expense generally, the transformation expense is low. Large-scale, the special engine bed especially is specially obvious. The common large-scale engine bed transforms, only spends the new engine bed purchase expense 1/3, the date of delivery is short. But some peculiar circumstances, like the high speed main axle, the tray automatic switching unit manufacture and the installment too requires a lot of work, costs a great deal of money, often transforms the cost to enhance 2 ~ 3 times, with purchases the new engine bed to compare, only can economical invest about 50%.

3.3.2 machine capability stable are reliable, the structure is limited

Uses foundation and so on lathe bed, column all is heavy but the firm casting component, but is not that kind of welding component, after the transformation engine bed performance high, the quality is good, may take the new equipment continues to use many years. But receives the original mechanism the limit, not suitably makes the unprecedented transformation.

3.3.3 familiar understood the equipment, is advantageous for the operation service

When purchases the new equipment, did not understand whether the new equipment can satisfy its processing request. The transformation then otherwise, may precisely calculate the engine bed the processing ability; Moreover, because many years use, the operator already understood to the engine bed characteristic, uses and services the aspect to train the time in the operation short, effective is quick. The transformation engine bed as soon as installs, may realize the capacity load revolution.

3.3.4 may fully use the existing condition

May fully use the existing ground, does not need to like buys when the new equipment such to have reto construct the ground.

3.3.5 may use the newest control technology

enhances the production equipment the automated level and the efficiency, improves the equipment quality and the scale, alters to the old engine bed now the horizontal engine bed.

When the numerical control system mainly has three kind of types, the transformation, should act according to the special details to carry on the choice.

    This system servo drive mainly is step-by-steps the electrical machinery, the power step-by-steps the electrical machinery, the battery solution pulse motor and so on. Entering sends out which by the numerical control system for instruction pulse, after the actuation electric circuit control and the power enlargement, causes to step-by-step the electrical machinery rotation, through gear vice- and ball bearing guide screw vice- actuation executive component. So long as the control command pulse quantity, the frequency as well as the circular telegram order, then may control the executive component movement the displacement quantity, the speed and the heading. This kind of system does not need the physical location and the velocity feedback which obtains to the input end, therefore called it the open system, this system displacement precision mainly decided in step-by-steps the electrical machinery angular displacement precision, transmission part and so on gear guide screw pitches the precision, therefore the system displacement precision is low.

This system structure simple, debugging service convenient, work reliable, cost low, is easy to reequip successfully.

4.2 The asynchronous motor or the direct current machine drive, diffraction grating survey feedback closed loop numerical control system

This system and the open system difference is: Physical location feedback signal which by position detector set and so on the diffraction grating, induction synchromesh obtains, carries on the comparison as necessary with the given value, two interpolations enlargements and the transformation, the actuation implementing agency, by the speed which assigns turns towards the elimination deviation the direction movement, until assigns the position and the feedback physical location interpolation is equal to the zero. The closed loop enters for the system

Enters for the system complex in the structure compared to the split-ring, the cost is also high, requests strictly to the environment room temperature. The design and the debugging is all more difficult than the open system. But may obtain compared to the split-ring enters for a system higher precision, quicker speed, actuation power bigger characteristic target. May act according to the product specification, decided whether uses this kind of system.

4.3 The direct current servo electrical machinery drives, encoder feedback semi-closure link numerical control system

    Half closed-loop system examination part installs in among passes in the moving parts, indirectly surveys the executive component the position. It only can compensate a system ring circuit interior part of part the error, therefore, its precision compared to closed-loop system precision low, but its structure and the debugging all compares the closed-loop system to be simple. In makes the angular displacement examination part and the speed examination part and the servo electrical machinery time a whole then does not need to consider the position detector set installs the question.

The current production numerical control system company factory quite are many, overseas famous company like German SIEMENS Corporation, Japanese FANUC Corporation; Native corporation like China Mount Everest Corporation, Beijing astronautics engine bed numerical control system group company, Central China numerical control company and Shenyang upscale numerical control country engineering research center.

When choice numerical control system mainly is each kind of precision which the engine bed must achieve after the numerical control transformation, actuates the electrical machinery the power and user's request.

A new numerical control engine bed, must achieve in the design that, Has the high static dynamic rigidity; Movement vice- between friction coefficient small, the transmission is ceaseless; The power is big; Is advantageous for the operation and the service. When engine bed numerical control transformation should meet the above requirements as far as possible. Cannot think the numerical control installment and the ordinary engine bed connects in has met the numerical control engine bed requirements together, but also should carry on the corresponding transformation to the major component to enable it to achieve the certain design request, can obtain the anticipated transformation goal.

    Said to the numerical control lathe that, the guide rail besides should have the conventional lathe guidance precision and the technology capability, but also must have good bears the friction, the attrition characteristic, and the reduction but sends the dead area because of the friction drag. At the same time must have the enough rigidity, by reduces the guide rail to distort to processes the precision the influence, must have the reasonable guide rail protection and the lubrication.

    The common engine bed gear mainly concentrates in the headstock and the gear box. In order to guarantee the transmission precision, on the numerical control engine bed uses the gear precision class is all higher than the ordinary engine bed. Must be able to achieve the ceaseless transmission in the structure, thus transforms time, the engine bed main gear must satisfy the numerical control engine bed the request, by guarantees the engine bed processing precision.

    The guide screw transmission relates directly to the transmission chain precision. The guide screw selects mainly is decided requests and drives the torque request in the job precision. Is  not used by job precision request Gao Shike skids the guide screw, but should inspect the original guide screw attrition situation, like the pitch error and the pitch accumulative error as well as matches the nut gap. The ordinary circumstances skid the guide screw to be supposed not to be lower than 6 levels, the nut gap oversized then replaces the nut. Uses skids the guide screw relative ball bearing guide screw price to be  low, but satisfies the precision high components processing with difficulty.

The ball bearing guide screw rubs loses slightly, the efficiency is high, its transmission efficiency may above 90%; Precision high, the life is long; When start moment of force and movement the moment of force approaches, may reduce the electrical machinery to start the moment of force. Therefore may satisfiedly compare the high accuracy components processing request.

The effect must take the security as a premise. Transforms in the engine bed must take the corresponding measure according to the actual situation, cuts noticeable. The ball bearing guide screw vice- is the precision part, when the work must take strict precautions against the dust is specially the scrap and the hard sand grains enters the roller conveyer. On longitudinal guide screw also coca overall sheet iron safety mask. The big carriage with skids two end surfaces which the guide rail contacts to have to seal, prevented absolutely the flinty granulated foreign matter enters the sliding surface damage guide rail.

Sixth, After the engine bed electrical system transformation, to operates, the programmers inevitably brings the new request. Therefore ahead of time carries on new system knowledge training to the operator and the programmers to be extremely important, after otherwise will affect the transformation the engine bed rapid investment production. The training content should include the new operation kneading board disposition, the function, the instruction meaning generally; New system functional scope, application method and with old system difference; Maintenance maintenance request; Programming standard and automated programming and so on. The key point is makes, gets a good grasp of the operating manual and the programming instruction booklet.

the numerical control transforms se Transforms the scope according to each equipment differently, must beforehand design the connection partial transformations, if transforms completely, should design the electro-mechanical transformation connection, the operation kneading board control and the disposition, the interconnection partial contacts, the parameter measuring point, services the position and so on, the request operates and services conveniently, reasonable, the line moves towards, center the small junction smoothly few, the strong and the weak electrical noise is smallest, has the suitable allowance and so on. Partial transformation, but also needs to consider the new old system the performance match, the voltage polarity and the size transformation, install the position, the digital-analog conversion and so on, when the necessity must manufacture the transformation connection voluntarily.

 

In 1998, the company invested 200,000 Yuan, with German Simens the 810M numerical control system, the 611A exchange servo drive system sds was the X53 milling machine carries on X, Y, the Z three axle numerical control transformation to a company's model; Retained the original main axle system and the cooling system; The transformation three axle has used the roller lead screw and the gear drive organization on the machinery. The entire transformation work including the machine design, the electrical design, the PLC procedure establishment and the debugging, the engine bed overhaul, finally is the entire machine installment and the debugging. After the milling machine transforms, processing effective stroke X/Y/The Z axis respectively is 88.0/270/28 billion mm; Maximum speed X/Y/The Z axis respectively is 5000/1500/800 mm/Min; Manual speed X/Y/The Z axis respectively is 3000/1000/500 mm/Min; The engine bed processing precision achieves ±0.001mm. The engine bed three coordinates linkage may complete each kind of complex curve or the curved surface processing.

In 2000, with Guangzhou numerical control plant production GSK980T numerical control system, the DA98 exchange servo unit and 4 locations automatic tool rests to an electrical machinery branch factory C6140 lathe X, the Z two axes carries on the numerical control transformation; Retained the original main axle system and the cooling system; The transformation two axes have used the roller lead screw and with the ambulacrum transmission system on the machinery. Entire transformation work including machine design, electrical design, engine bed overhaul and entire machine installment and debugging. After the lathe transforms, processing effective stroke X/The Z axis respectively is 3.90/73 million mm; Maximum speed X/The Z axis respectively is 120.0/3 million mm/Min; The manual speed is 400mm/Min; Manual is fast is X/The Z axis respectively is 120.0/3 million mm/Min; The engine bed smallest migration unit is 0.001mm.

In 2000, the company invests 120,000 Yuan, with German Simens the 802S numerical control system, step-by-steps the actuation system is the X53 milling machine carries on X, Y, the Z three axle numerical control transformation to company's another model; Retained the original main axle system and the cooling system; The transformation three axle has used the roller lead screw and the gear drive organization on the machinery. The entire transformation work including the machine design, the electrical design, the engine bed overhaul, finally is the entire machine installment and the debugging. After the milling machine transforms, processing effective stroke X/Y/The Z axis respectively is 63.0/240/28 billion mm; Maximum speed X/Y/The Z axis respectively is 3000/1000/600 mm/Min; Manual enters for speed X/Y/The Z axis respectively is 200.0/800/5 billion mm/Min; The smallest motion unit is 0.001mm.

1  数控系统发展简史及趋势 

1946年诞生了世界上第一台电子计算机，这表明人类创造了可增强和部分代替脑力劳动的工具。它与人类在农业、工业社会中创造的那些只是增强体力劳动的工具相比，起了质的飞跃，为人类进入信息社会奠定了基础。

　　6年后，即在1952年，计算机技术应用到了机床上，在美国诞生了第一台数控机床。从此，传统机床产生了质的变化。近半个世纪以来，数控系统经历了两个阶段和六代的发展。

1.1  数控（NC）阶段（1952～1970年） 

　　早期计算机的运算速度低，对当时的科学计算和数据处理影响还不大，但不能适应机床实时控制的要求。人们不得不采用数字逻辑电路"搭"成一台机床专用计算机作为数控系统，被称为硬件连接数控（HARD-WIRED NC），简称为数控（NC）。随着元器件的发展，这个阶段历经了三代，即1952年的第一代--电子管；1959年的第二代--晶体管；1965年的第三代--小规模集成电路。

　　到1970年，通用小型计算机业已出现并成批生产。于是将它移植过来作为数控系统的核心部件，从此进入了计算机数控（CNC）阶段（把计算机前面应有的"通用"两个字省略了）。到1971年，美国INTEL公司在世界上第一次将计算机的两个最核心的部件--运算器和控制器，采用大规模集成电路技术集成在一块芯片上，称之为微处理器（MICROPROCESSOR），又可称为中央处理单元（简称CPU）。

　　到1974年微处理器被应用于数控系统。这是因为小型计算机功能太强，控制一台机床能力有富裕（故当时曾用于控制多台机床，称之为群控），不如采用微处理器经济合理。而且当时的小型机可靠性也不理想。早期的微处理器速度和功能虽还不够高，但可以通过多处理器结构来解决。由于微处理器是通用计算机的核心部件，故仍称为计算机数控。

　　到了1990年，PC机的性能已发展到很高的阶段，可以满足作为数控系统核心部件的要求。数控系统从此进入了基于PC的阶段。

　　总之，计算机数控阶段也经历了三代。即1970年的第四代--小型计算机；1974年的第五代--微处理器和1990年的第六代--基于PC（也就是为PC-BASED）。

1.3.1　继续向开放式、基于PC的第六代方向发展

　　基于PC所具有的开放性、低成本、高可靠性、软硬件资源丰富等特点，更多的数控系统生产厂家会走上这条道路。至少采用PC机作为它的前端机，来处理人机界面、编程、联网通信等问题，由原有的系统承担数控的任务。PC机所具有的友好的人机界面，将普及到所有的数控系统。远程通讯，远程诊断和维修将更加普遍。

1.3.2　向高速化和高精度化发展

　　这是适应机床向高速和高精度方向发展的需要。

1.3.3　向智能化方向发展

随着人工智能在计算机领域的不断渗透和发展，数控系统的智能化程度将不断提高。

（1）应用自适应控制技术

　　数控系统能检测过程中一些重要信息，并自动调整系统的有关参数，达到改进系统运行状态的目的。

　（2）引入专家系统指导加工

　　将熟练工人和专家的经验，加工的一般规律和特殊规律存入系统中，以工艺参数数据库为支撑，建立具有人工智能的专家系统。

  （3）引入故障诊断专家系统

　（4）智能化数字伺服驱动装置

　 可以通过自动识别负载，而自动调整参数，使驱动系统获得最佳的运行。

2  机床数控化改造的必要性 

　　从微观上看，数控机床比传统机床有以下突出的优越性，而且这些优越性均来自数控系统所包含的计算机的威力。

2.1.1 可以加工出传统机床加工不出来的曲线、曲面等复杂的零件。

　　由于计算机有高超的运算能力，可以瞬时准确地计算出每个坐标轴瞬时应该运动的运动量，因此可以复合成复杂的曲线或曲面。

2.1.2 可以实现加工的自动化，而且是柔性自动化，从而效率可比传统机床提高3～7倍。

　　由于计算机有记忆和存储能力，可以将输入的程序记住和存储下来，然后按程序规定的顺序自动去执行，从而实现自动化。数控机床只要更换一个程序，就可实现另一工件加工的自动化，从而使单件和小批生产得以自动化，故被称为实现了"柔性自动化"。

2.1.3 加工零件的精度高，尺寸分散度小，使装配容易，不再需要"修配"。

2.1.4 可实现多工序的集中，减少零件 在机床间的频繁搬运。

2.1.5 拥有自动报警、自动监控、自动补偿等多种自律功能，因而可实现长时间无人看管加工。

2.1.6 由以上五条派生的好处。

　　如：降低了工人的劳动强度，节省了劳动力（一个人可以看管多台机床），减少了工装，缩短了新产品试制周期和生产周期，可对市场需求作出快速反应等等。

　　以上这些优越性是前人想象不到的，是一个极为重大的突破。此外，机床数控化还是推行FMC（柔性制造单元）、FMS（柔性制造系统）以及CIMS（计算机集成制造系统）等企业信息化改造的基础。数控技术已经成为制造业自动化的核心技术和基础技术。

　　从宏观上看，工业发达国家的军、民机械工业，在70年代末、80年代初已开始大规模应用数控机床。其本质是，采用信息技术对传统产业（包括军、民机械工业）进行技术改造。除在制造过程中采用数控机床、FMC、FMS外，还包括在产品开发中推行CAD、CAE、CAM、虚拟制造以及在生产管理中推行MIS（管理信息系统）、CIMS等等。以及在其生产的产品中增加信息技术，包括人工智能等的含量。由于采用信息技术对国外军、民机械工业进行深入改造（称之为信息化），最终使得他们的产品在国际军品和民品的市场上竞争力大为增强。

3  数控化改造的内容及优缺 

　　在美国、日本和德国等国家，机床改造作为新的经济增长行业，生意盎然，正处在黄金时代。由于机床以及技术的不断进步，机床改造是个"永恒"的课题。在美国、日本、德国，用数控技术改造机床和生产线具有广阔的市场，已形成了机床和生产线数控改造的新的行业。在美国，机床改造业称为机床再生（Remanufacturing）业。从事再生业的著名公司有：Bertsche工程公司、ayton机床公司、Devlieg-Bullavd（得宝）服务集团、US设备公司等。。在日本，机床改造业称为机床改装（Retrofitting）业。从事改装业的著名公司有：大隈工程集团、岗三机械公司、千代田工机公司、野崎工程公司、滨田工程公司、山本工程公司等。

机床与生产线的数控化改造主要内容有以下几点：

其一是恢复原功能，对机床、生产线存在的故障部分进行诊断并恢复；

其二是NC化，在普通机床上加数显装置，或加数控系统，改造成NC机床、CNC机床；

其三是翻新，为提高精度、效率和自动化程度，对机械、电气部分进行翻新，对机械部分重新装配加工，恢复原精度；对其不满足生产要求的CNC系统以最新CNC进行更新；

其四是技术更新或技术创新，为提高性能或档次，或为了使用新工艺、新技术，在原有基础上进行较大规模的技术更新或技术创新，较大幅度地提高水平和档次的更新改造。

3.3.1　减少投资额、交货期短

　　同购置新机床相比，一般可以节省60％～80％的费用，改造费用低。特别是大型、特殊机床尤其明显。一般大型机床改造，只花新机床购置费用的1/3，交货期短。但有些特殊情况，如高速主轴、托盘自动交换装置的制作与安装过于费工、费钱，往往改造成本提高2～3倍，与购置新机床相比，只能节省投资50％左右。

3.3.2　机械性能稳定可靠，结构受限

　　所利用的床身、立柱等基础件都是重而坚固的铸造构件，而不是那种焊接构件，改造后的机床性能高、质量好，可以作为新设备继续使用多年。但是受到原来机械结构的限制，不宜做突破性的改造。

3.3.3　熟悉了解设备、便于操作维修

　　购买新设备时，不了解新设备是否能满足其加工要求。改造则不然，可以精确地计算出机床的加工能力；另外，由于多年使用，操作者对机床的特性早已了解，在操作使用和维修方面培训时间短，见效快。改造的机床一安装好，就可以实现全负荷运转。

3.3.4　可充分利用现有的条件

3.3.5　可以采用最新的控制技术

    该系统的伺服驱动装置主要是步进电机、功率步进电机、电液脉冲马达等。由数控系统送出的进给指令脉冲，经驱动电路控制和功率放大后，使步进电机转动，通过齿轮副与滚珠丝杠副驱动执行部件。只要控制指令脉冲的数量、频率以及通电顺序，便可控制执行部件运动的位移量、速度和运动方向。这种系统不需要将所测得的实际位置和速度反馈到输入端，故称之为开环系统，该系统的位移精度主要决定于步进电机的角位移精度，齿轮丝杠等传动元件的节距精度，所以系统的位移精度较低。

　　该系统结构简单，调试维修方便，工作可靠，成本低，易改装成功。

    该系统与开环系统的区别是：由光栅、感应同步器等位置检测装置测得的实际位置反馈信号，随时与给定值进行比较，将两者的差值放大和变换，驱动执行机构，以给定的速度向着消除偏差的方向运动，直到给定位置与反馈的实际位置的差值等于零为止。闭环进给系统在结构上比开环进给系统复杂，成本也高，对环境室温要求严。设计和调试都比开环系统难。但是可以获得比开环进给系统更高的精度，更快的速度，驱动功率更大的特性指标。可根据产品技术要求，决定是否采用这种系统。

    半闭环系统检测元件安装在中间传动件上，间接测量执行部件的位置。它只能补偿系统环路内部部分元件的误差，因此，它的精度比闭环系统的精度低，但是它的结构与调试都较闭环系统简单。在将角位移检测元件与速度检测元件和伺服电机作成一个整体时则无需考虑位置检测装置的安装问题。

　　当前生产数控系统的公司厂家比较多，著名公司的如德国SIEMENS公司、日本FANUC公司。

    选择数控系统时主要是根据数控改造后机床要达到的各种精度、驱动电机的功率和用户的要求。

5  数控改造中主要机械部件改装探讨 

　　一台新的数控机床，在设计上要达到：有高的静动态刚度；运动副之间的摩擦系数小，传动无间隙；功率大；便于操作和维修。机床数控改造时应尽量达到上述要求。不能认为将数控装置与普通机床连接在一起就达到了数控机床的要求，还应对主要部件进行相应的改造使其达到一定的设计要求，才能获得预期的改造目的。

    对数控车床来说，导轨除应具有普通车床导向精度和工艺性外，还要有良好的耐摩擦、磨损特性，并减少因摩擦阻力而致死区。同时要有足够的刚度，以减少导轨变形对加工精度的影响，要有合理的导轨防护和润滑。

    一般机床的齿轮主要集中在主轴箱和变速箱中。为了保证传动精度，数控机床上使用的齿轮精度等级都比普通机床高。在结构上要能达到无间隙传动，因而改造时，机床主要齿轮必须满足数控机床的要求，以保证机床加工精度。

    丝杠传动直接关系到传动链精度。丝杠的选用主要取决于加工件的精度要求和拖动扭矩要求。被加工件精度要求不高时可采用滑动丝杠，但应检查原丝杠磨损情况，如螺距误差及螺距累计误差以及相配螺母间隙。一般情况滑动丝杠应不低于6级，螺母间隙过大则更换螺母。采用滑动丝杠相对滚珠丝杠价格较低，但难以满足精度较高的零件加工。

　　滚珠丝杠摩擦损失小，效率高，其传动效率可在90%以上；精度高，寿命长；启动力矩和运动时力矩相接近，可以降低电机启动力矩。因此可满足较高精度零件加工要求。

6  数控改造几个实例 

    2001年，用德国西门子810M数控系统、611A交流伺服驱动系统对公司的一台型号为X53的铣床进行X、Y、Z三轴数控改造；保留了原有的主轴系统和冷却系统；改造的三轴在机械上采用了滚轴丝杆及齿轮传动机构。整个改造工作包括机械设计、电气设计、PLC程序的编制与调试、机床大修，最后是整机的安装和调试。铣床改造后，加工有效行程X/Y/Z轴分别为880/270/280 mm；最大速度X/Y/Z轴分别为5000/1500/800 mm/min；手动速度X/Y/Z轴分别为3000/1000/500 mm/min；机床加工精度达到±0.001mm。机床的三坐标联动可完成各种复杂曲线或曲面的加工。

    2004年，GSK980T数控系统、DA98交流伺服单元及4工位自动刀架对电机分厂的一台C6140车床X、Z两轴进行数控改造；保留了原有的主轴系统和冷却系统；改造的两轴在机械上采用了滚轴丝杆及同步带传动机构。整个改造工作包括机械设计、电气设计、机床大修及整机的安装和调试。车床改造后，加工有效行程X/Z轴分别为390/730 mm；最大速度X/Z轴分别为1200/3000 mm/min；手动速度为400mm/min；手动快速为X/Z轴分别为1200/3000 mm/min；机床最小移动单位为0.001mm。

    2004年，用德国西门子802S数控系统、步进驱动系统对公司的另一台型号为X53的铣床进行X、Y、Z三轴数控改造；保留了原有的主轴系统和冷却系统；改造的三轴在机械上采用了滚轴丝杆及齿轮传动机构。整个改造工作包括机械设计、电气设计、机床大修，最后是整机的安装和调试。铣床改造后，加工有效行程X/Y/Z轴分别为630/240/280 mm；最大速度X/Y/Z轴分别为3000/1000/600 mm/min；手动进给速度X/Y/Z轴分别为2000/800/500 mm/min；最小移动单位为0.001mm。