4，要多实践，进行“小改小革”

往往在正常工作中发生某一元件损坏（如选择开关、按钮、继电器等）而暂无备件时，自己动手尽可能用粘合法等办法修复或采用暂时的特殊办法，使机床能正常工作下去，等到备件来后再恢复。比如：德国 VDF 数控大车的第 2 刀板中有 5 个的微型压力开关（夹紧刀板用的），其中 2 只微型开关不慎损坏，而无备件，我们采用了 " 短接法" ，使压力开关的触点符合 PLC 的输入条件，使机床不报警又能正常工作下去了。有时机械使用时间长后，定位精度差了，产生了定位报警，在无法重新调整机床的情况下可暂时修正机床参数，加大“公差”带，使之又能正常工作。总之，这样的办法还很多。多实践，会出现更多的办法。

5，要多实践，当好一名优秀的“维护师”

我们不但要多实践，炼就一身过硬的维修本领；而且依高度负责的精神，当好一名优秀的“维护师”,把隐患和故障苗子消灭在萌芽状态。搞好数控机床的保养工作（包括日常维护和一﹑二级保养），非常重要。这可以减少故障，延长机床的使用寿命，保证机床长时间稳定可靠地运行。比如：电气柜的通风口防尘的过滤网,如果不定期清洁和更换，有可能长期下来滤网堵塞而引起电气柜过热。严重的话引起数控板子损坏，后果十分严重。建议维修人员有空经常到数控机床去一去﹑看一看﹑动动手，对于减少故障十分有效。　

6，要多实践，要自己动手修板子

一般说来数控机床的电路板可靠性好，故障率极低，一般去检查数控机床时，不要先怀疑板子的问题。比如：西门子 850 系统，有时会出现 41 NC-处理器报警或 43 PLC-处理器报警，实际上并不是板子有故障，可以通过 "拆拔法" ，进行收据控制初始化，或冷热启动 PLC 等方法试验，一般可以排除。若确实证明是电路板问题时，要进行修复。这些板（一般无图纸）价格昂贵，一般要几千元-几万元，对于每个企业来说“备件难”，价格太贵了，备不起。因此，数控机床电路板的好坏极为重要，一旦电路板损坏而无备件，一时又修不好，势必会停机，严重影响生产。根据我们的经验，有时往往电路板只是一个极小的故障，只要认真检查，不难发现问题。我们已经多次发现个别电容漏电、板子虚焊、短路等故障，是能够修好的。有些电路板故障比较复杂，但是只要化时间，通过用仪器检查，还是能够修好的；但还有部分电路板情况严重，特别是大规模集成电路，维修困难，加上原器件无备件，应该提早送到专业维修公司进行维修或购买相同的备板。自己动手修板子，有很大好处，一方面可以为企业节约成本，解决燃眉之急；另一方面可以“解剖麻雀”熟悉电子电路，培养自己的分析判断和动手能力是非常有益的。

　　通过了二十年来的维修实践，我们也感到外国人设计的数控机床，特别是大型的数控机床也不是十全十美的，也存在不少问题和缺陷。通过我们对数控机床的学习、深化，找出其中问题的所在，大胆地对有些问题进行改进，取得了较好的效果。比如德国 VDF 数控大车，原设计 2 只静压托架通电后就工作，静压泵连续运转，这样又浪费电能，同时又缩短了进口泵的寿命。我们通过 PLC 进行了修改，增加了 2 只开关，只化费了几十元钱，使 2 只静压托架可根据需要任意地开或停，这样延长了进口泵的寿命，全年可节电 2 万多度。还有 INGERSOLL 叶轮槽铣原设计中，主铣头及副铣头只有反向铣削，而没有同向铣削。在加工高中压转子第 20 级叶轮时，由于叶轮间距离小，不能用反向铣削，因此只能用一个铣头进行加工。经过我们研究，巧妙地改动了二个铣头的接线，修改了 PLC 程序，结果几乎没有化钱，实现了同向铣削。现在可二个铣头可以同时加工，提高工效一倍，可提前 3-4 天完成加工转子的任务。因此，我们要进一步挖掘数控机床的潜力，更好地发挥它的威力为生产服务。　　尽管数控机床故障复杂，千变万化，只要我们认真对待，培养一支高素质的机电一体化的维修队伍。通过“五多”法，即多看、多问、多记﹑多思、多练、积累经验，掌握维修技巧，融会贯通，我们一定能够主要依靠自己的力量，把数控机床修好、用好、管好。(原创)

Talk about how to repair NC machine?谈谈怎样修好数控机床? (英文版)

It is well known that NC machine is high efficient, high accuracy and high adaptability machining equipment, which plays a most important role in and production. NC machine incorporates current high and new technologies, including machine, electrical, pneumatic and optical. Electrical is very complex and many crossing tubes on the machine. NC system is diversified from its kinds, at least hundreds of kind since 70^th last century to now. Furthermore, spare parts are not preserved and can’t be exchanged each other. Taking our company for example, there are more than forty NC machines, among which there are twenty kinds of NC system. Therefore, the troubles are variety and always not the same. Particularly, large and heavy duty NC machine is not only expense in price, about millions US dollars for each unit, moreover, it takes several months to one more year to install and adjustment. Due to thousands of parts, any minor problem of them will cause machine malfunction. Furthermore, there are complicated tubes and wiring connection, any minor problem of them will yield big problem. Normally, NC machine is used in three shift with fully capacity continuously. Furthermore, the large and heavy duty NC machine is big in size and placed in no air condition building. Therefore the environment exerts big effect to machine and is easy to cause problem. For ordinary enterprises, they are always embarrassed by “maintenance difficulties”. Even for specialized maintenance team, they will also face tough task to maintain varieties NC machine.

Since our country introduced and manufacturing so many NC machine, how can we find an efficient way to remedy troubles, find out hidden troubles and remove trouble rapidly. My opinion is that: firstly, we should take high responsibility and spirit without fearing difficulty. Secondly, we should take great effort to make good command of NC technology. Based on about twenty years’ NC machine maintenance experiences, I put forward so called “five more” method, i.e. “read more, ask more, record more, think more, and practice more” to raise own technical expertise and maintenance capability gradually, adapting to very kinds of complicated situation and resolving difficult problem for the purpose of repairing NC machine. 

(一).Read more

1.   Read more NC information

We should understand characteristics and functions of every kind of NC system and PLC programmable controller; understand NC system alarm and handling method. Meanwhile, we should also understand the meaning of data controlling, PLC machine program setting; familiarize PLC programmable language and NC programming method. Moreover, we should understand control panel operation and the contents of each menu, particular understand features of main spindle, feeding motor and it’s driver etc. Facing with a pile of NC machine information, how to look it first? I think that we should focus on key issues to thoroughly understand basic composition and configuration of NC system and block diagram. We should clear the whole process from beginning to end. Skim the rest of them and read quickly. Because NC system internal wiring diagram is very complicated, and manufacturer doesn’t provide wiring diagram, it is unnecessary to understand thoroughly. For example, NX-154 blading machine is adopted A-B10 system (four spindles and simultaneous five axes machine). We should focus on typical system configuration and understand the card function, interface layout and lamp meaning etc. Nowadays, because NC machine is updated quickly and exists many kinds of NC system, there are much difference for different manufacturers and types. Therefore, we must distinguish their commonality and particularity to know them difference clearly. In general, people who can handle SIEMENS NC system might not handle A-B or FANUT NC system trouble as skill as SIEMENS NC system. To overcome the weakness, we should observe more and study continuously to upgrade our knowledge.  

2    Read and digest more electrical diagrams

For every electrical device, such as, contactor, relay, time relay etc. and PLC input and output should be noted in electrical diagrams. For example, 1A1 stands for contactor for hydraulic pump 1 M starting. Normally, the constant opening contact and constant closing contact should be noted below the diagrams. Therefore, responding constant opening contact and constant closing contact 1A1 in certain page should be noted as hydraulic pump starting. For electrical diagrams of large NC machine, consisted of dozens, even hundreds of page, sometimes it takes us several times to understand each device functions and indicate notes on diagrams. Therefore, for above-mentioned starting hydraulic pump 1 M, we should indicate clearly which output of PLC drives contactor 1 A1 in motion. However, for some block diagrams in electrical diagrams, such as diver of each axes, as long as we know certain control conditions (on and off conditions), we can study and take into account in later spare time for detail. Firstly, we must make clear difference of each country electrical symbol and study PLC sentence tables compiled by manufacturer to understand their programming languages. Meanwhile, we should make notes on the basis of understanding. In this doing, we can greatly save time in removing troubles. If we begin to understand electrical diagram, PLC sentence table after troubles has already occurred, it will take us much time, to make matter worse, it will result in false judgment. 

3    Read more hydraulic and pneumatic diagrams and digest them deeply.

We should make clear about functions and history of NC machine mechanical, hydraulic and pneumatic diagrams, and make notes on drawings. For example, German COBURG NC gantry milling machine’ s attachment and cutter installation are rather complicated, we should analyze drawings step by step to make note which solenoid valve initiates locking cutter, which PLC output it is responding and how many inputs are there. In this way, we can see whole process through from electric to hydraulic ﹑ pneumatic and mechanical. Particularly, we should focus on special parts of interrelation of electrical and mechanical.  For example, Italia INNSE NC boring and milling machine makes Y-axis compensation by means of electrical-hydraulic proportional valve technology. Therefore, we should lay emphasis on its roles and functions, particularly, understand its adjustment method and data, proportional valve electricity in static and dynamic and responding pressure of balancing oil pump. If we can be good command of not only electrical, but also mechanical, which is so called integrated electrical and mechanical, we will have more capability to resolve problems. 

4    Read more foreign language to raise foreign language reading ability

If we don’t understand foreign language (English), we can’t read a lot of foreign language technical information, resulting in difficult to repair NC machine. It is also unrealistic to rely on too much translator. Although we may feel some difficulties to read foreign language technical information due to many new vocabularies, practice make perfect, if we persist to read more, later we will read them more easy. We must raise our reading capability, especially in English and read more information without through translation. A qualified maintenance people should have command of basic language tool. Of course, it is better to discuss with foreign experts with oral language.

(二) Ask more 

1   ask more relevant experts

You had better to seize the chances to train abroad or contact with foreign experts when they come to your company to install and adjust machine. It is best learning opportunity. In this doing, you have chance to obtain many experiences and get more knowledge in installing and adjusting machine, such as, machine secret parameter and password, recovery method after PLC, MMC lose, electrical correction method after laser measuring each axis accuracy. Ask more and make clear when you feel confusion. Through this period, you can achieve a lot and obtain many internal information and manuals (it is confidential to customers). After machine is put into operation, we should also keep close relationship with foreign experts and manufacturers and get maintenance and consultation by e-mail or fax. In this doing, we can get further advice and information from them to resolve machine troubles, and also get special spared parts. Meanwhile, we should also keep close contact with NC system agent, such as American A-B, German SIEMENS, Japan FANUC, Spanish FAGOR etc. companies. Therefore, we can not only get further consultation and NC system updated information and spare parts, also can have chance to attend NC machine symposium or special training courses to get system study to raise our maintenance capability greatly.  

2    Ask more operators.

After troubles happen, firstly we should go to operators to know whole process of trouble. If we fail to ask operator, or just ask causally, we won’t get correct on-site information and even result wrong judgment. Therefore, we should ask more and detail, such as, how about whole process of trouble (origination, proceeding, and finish), which alarm signals have been initiated, when the alarm begin, which devices have been operated, which part has been contacted, what functions have been corrected, how about external environment?  It is half success if we list troubles based on fully field investigation and what had happened on-site. Thereafter, we can make further analysis to seize main problems and solve it. For operators with rich experience are very familiar with machine operation and machining procedure, as well as machine common troubles. Therefore, it is very helpful to remove troubles cooperating with these operators closely.

3    Ask more colleagues

If you have no chance to access to repair machine, just ask the people who engaging in maintenance, what had happened and how did they remove troubles? To raise our capability, we also should learn from colleagues with rich experiences to learn the trick and methods how to remove troubles, particularly learn from old maintenance people with rich experience in order.

(三) Record more 

1    Record relevant parameters of NC machine.

Specially record all kinds of relevant parameters after machine has being adjusted, such as control machine parameters, PLC machine parameters, MMC machine management parameters, screw pitch deviation compensation, PLC program, main programs, cycle programs and macro programs in machining. We must use floppy disk to record above-mentioned data on file and keep a copy in hand for daily maintenance need. Furthermore, we should record current, voltage, speed etc. data of main spindle and each axis motor as the basis of driving part trouble judgment. Also, we had better record the status (on or off) and all input and output LED (light, dark, or glitter) in electrical cabinet or record PLC status IB (input bit), QB (output bit) is 0 or1 on CRT when they are energized and official working. In doing so, we can benefit a lot from these records. For example, one German SCHIESS NC machine has occurred Z-axis driving malfunction. By comparing normal operation and abnormal condition in PLC status (0,1), we find out root trouble is that one comparison relay is abnormal in status. After adjustment, the trouble has been removed quickly.