Numerical control machine tool is a kind of high technical content machine, electric, instrument integration of efficient automatic tools, a combination of computer technology, automation technology, servo drive, precision measurement and precision machinery and other fields of new technological achievements, is an emerging industrial control technology.Although different nc system on the structure and performance, but has its generality on fault diagnosis, combined the actual work now talk about the numerical control system and the method of fault analysis and repair.Numerical control system fault maintenance usually according to: field of fault diagnosis and analysis, fault measurement, system commissioning to repair and eliminate the three big step.1, nc machine tool fault diagnosis in the fault diagnosis should grasp the following principles: 1.1 after the first external internal modern numerical control system can be * sex is higher and higher, the numerical control system itself more and more low failure rate, while most of the fault is caused by the system itself.Due to the numerical control machine tool is integrating mechanical, hydraulic, electric machine, its failure will be reflected by the three integrated.Maintenance personnel should be outside-in on a screen.Avoid unsealed at random, disassembly, otherwise it will enlarge the fault, reduce loss of machine tool accuracy, performance.System of external fault is mainly due to the detection switch, hydraulic components, pneumatic components, electric actuators, and cause the problems of mechanical device and so on.1.2 after the first mechanical electrical in general, mechanical failure find more easily, and numerical control system and electrical fault diagnosis is difficult.Before troubleshooting, first of all, pay attention to rule out the failure of mechanical.1.3 first after static dynamic, first in the stationary state of power machine, through understanding, observing, testing, analysis, confirm will not result in a failure to expand after the power supply, after the accident, may give machine electricity.In running state, dynamic observation, inspection and testing, to find fault.For the destructive failure will happen after the power supply, you must first, after eliminating the risk before electricity.1.4 after simple first when there is a variety of complex fault interweave each other, at that time do not know how to start, should first solve the problem of easy, after solve difficult problems.Often after solve simple problem, difficult problem may also be easier.2, numerical control machine tool numerical control system fault diagnosis technology is the high technology-intensive product, if you want to quickly and find out the reason and to determine the fault parts of the right, to the use of diagnostic techniques.With the continuous development of the microprocessor, and diagnosis technology is also by simple diagnostic towards versatile senior or intelligent direction.Diagnostic ability strong and the weak is also an important index for CNC numerical control system performance evaluation.The diagnosis technology of various kinds of CNC systems in use today can be roughly divided into the following categories: 2.1 starting diagnostic starting refers to each from the beginning of the electricity, the CNC system internal diagnostic procedures will automatically perform.The content of the diagnosis for the key in the system hardware and system control software, such as CPU, memory and I\/O module, and MDI\/CRT unit, paper tape reader, device or an external device such as a floppy disk unit.Only when the whole project after confirmation is correct, the system can enter into the normal operation of the ready state.Otherwise, will be in the CRT screen or leds indicate fault information in alarm mode.At this point starting diagnosis process cannot end, system cannot be put into operation.2.2 on-line diagnosis on-line diagnosis is to point to by the inside program of CNC system, when the normal operation of the system of the CNC system and CNC device connected to the servo unit, servo motor, spindle servo unit and the spindle motor and external equipment for automatic diagnosis and examination.As long as the system outage, on-line diagnosis will not stop.Online diagnosis generally includes state show that there are thousands of self-diagnosis function, often in binary 0 and 1 to display its state.For positive logic 0 means off state, said on state, with the help of status display can judge the failure parts.Commonly used interface state and internal status display, such as the use of I\/O interface status display, combining PLC ladder diagram and the high voltage control circuit diagram, the reasoning method and the method can determine the position of the point of failure in the real.Fault information mostly take the form of alarm number.Generally can be divided into the following categories: overheating alarm classes;The system alarm classes;Storage alarm classes;Programming\/set class;Servo classes;Travel switch alarm classes;The connection between the printed circuit board fault class.2.3 off-line diagnosis index of diagnosis is a control system malfunction, numerical control system manufacturer or professional repair center by using special diagnostic software and test device to stop (or offline).Make the fault location to as small as possible, within the scope of the part such as narrowed to a function module, circuit, or even a chip or components, the more accurate fault location.2.4 modern diagnostic technology with the development of telecommunications technology, IC and microcomputer price rise, in recent years abroad have put some new concepts and methods succeeded in reference to the diagnosis.(1) communication diagnosis also calls the remote diagnosis, the use of telephone communication line with faults of CNC system and professional repair centers dedicated communication diagnostic computer through the connection test.Such as Siemens ag in the diagnosis of CNC system adopted the diagnosis function, the user in the CNC system dedicated & other;Communication interface & throughout;Connection on the ordinary telephone lines, and two doors company special newsletter diagnosis of computer maintenance center & other;Data throughout the phone &;Also connected to the phone lines, and then sent to the CNC system by computer diagnostic procedures, and the test data back to the computer is analyzed and concluded that then diagnosis and treatment way to notify the user.Communication diagnosis system can also make regular preventive diagnosis for users and maintenance staff don’t need to attend, just to make a series of machine tools according to the predetermined time running examination, analysis of diagnosis in the center of the maintenance data, can be found the problems, so as to take measures as early as possible.Of course, this type of CNC system must have the remote diagnosis interface and networking.(2) the self-healing system is set in the system have a backup module, in the software of CNC system is equipped with the repair procedure, when the software is running once found a module has a failure, the system on the one hand, the fault information is displayed in the CRT, automatically looking for whether there is a spare module at the same time, if there are any spare module, the system can automatically make the fault offline, and through to the standby module the system can quickly enter the normal working condition.This scheme applies to unattended automation work situation.Need to be aware that there are some faults in the machine tools in the actual use without alarm, phenomenon also is not very obvious, in this case, the process is not so simple.After the other there is the equipment failure, not only no alarm information, and the lack of information on maintenance required.For this kind of fault diagnosis processing, must be carefully check according to the concrete situation, carries on the analysis from the phenomenon of tiny, find out the real reason for it.To the cause of such failure was found, you must first find from various surface mount its real failure phenomenon, from confirmed fault phenomenon to find out the reason of occurring.Comprehensive analysis of a fault phenomenon is one of the important factors to determine whether the correct.Before to find the cause of the problem, you must first understand the following situation: the fault is in the normal work or just boot occurs;Mountain is the number of times is the first time or have occurred many times;Confirm the correctness of the machine tool processing program;If anyone else 3, the common troubleshooting methods of the nc machine tools because of nc machine tool fault is more complex, at the same time, nc system self-diagnosis ability can not all parts of the system test, is often a alarm number to indicate the number of the cause of the problem, make it difficult to start.Below is the maintenance personnel for troubleshooting methods commonly used in production practice.Visual test method is 3.1 maintenance personnel according to the failure of various abnormal phenomena such as light, sound, taste of observation, determine the scope of the fault, the fault can be narrowed to a module or on a piece of circuit board, and then to eliminate.Generally includes: a. ask: ask fault field personnel carefully failure process, failure surface and failure consequences, etc.;B. visual: overall check whether the machine parts working status in normal state, the electric control device for emergency instructions, local burn out, check whether insurance components burnt fall off, craze, wires and cables, each operation element position correctly or not, etc.C. touch: under the condition of the machine power can touch the main circuit board installation condition, the condition of each connector plug, the power and signal connection status of the wire and hand touch and light wave components, especially large volume resistance capacity, semiconductor devices have a loose sense, to check out some of the broken foot, virtual welding, such as poor contact fault;D. power: it is to point to in order to check whether smoking, lighter, with or without abnormal sounds, smells and touch any motor overheating and components exist and electricity, once discovered immediately without electricity for analysis.If there is a destructive failure, must eliminate rear can electricity.Example: a CNC machining center is running after a period of time, the CRT display suddenly show no fault, and the machine also can continue to operate.After downtime to open and everything is ok.Observed that in the process of the equipment operation, failure may occur when in vibration.Preliminary judgment is poor contact element.When checking for a display panel, the CRT display suddenly disappeared.Inspection found a crystal vibration of two pins are loose virtual welding.After welding, fault elimination.3.2 initialization reset method usually, caused by transient fault alarm system, the available hardware reset or switch power supply, in turn, to clear the fault.Because if the system storage area off electricity, chaotic circuit board or the battery voltage, it must be initialized to the system to clear, clear before to make a good record of data copies should be paid attention to, if the fault is still cannot be ruled out after initialization, hardware diagnosis.Example: a CNC lathe when press the run button, a microcomputer refused to carry out the processing procedure, also don’t show breakdown self check tips, the display in the reset state (only display menu).Sometimes manually, editing function is normal, check the user program, various parameters exactly;Sometimes because of the memory cell failure, replace the memory cell and so on, the system displays a certain direction or the size of each direction on the super size by the most (display size more than maximum size of the machine can real jin processing or exceed the maximum size of the system to be able to recognise).Elimination method: initialize the reset method is used to make the system reset reset (usually with a special combination of rehabilitation or password).3.3 since the diagnosis method of CNC system has the function of strong self-diagnosis, and can at any time to monitor the working state of the hardware and software of CNC system.Use of self-diagnosis function, can show the state of the system and the interface between the host information, so as to determine the fault occurred in mechanical parts and CNC, and show the general parts of the fault, fault code).A. hardware alarm indication: refers to, including CNC system, servo system, the various states and fault indicator light on the electrical devices, combined with light state and melody & Phi;The tomb & delta;Qin to martingale accept 1 Shan gansu jiu ChenJing Hang closed show Qi brachial flint pepper m:?BR>B. software alarm indication: system software, PLC program and process of fault alarm display normally, according to the display of alarm, control the corresponding diagnostic manual possible fault causes and elimination method may be revealed.3.4 feature program testing function test method is the numerical control system of G, M, S, T, F function by programming method into a functional test procedure, and stored in the corresponding medium, such as paper tape and tape, etc.Run the program in fault diagnosis, can quickly determine the probable cause of the failure.Functional program testing is often used in the following situations: a. machine tool processing waste caused by uncertain programming is improper operation, or CNC system failure caused b. random failures, CNC system, is difficult to difference between outside interference, or is there a good system stability;C. longer CNC machine idle time before put into use or preventive maintenance of CNC machine tool.Example: a FANUC9 system of vertical milling machine in automatic machining one curve parts appear crawl phenomenon, the surface roughness is poor.When run the test program, linear and circular interpolation stoppage is no creeping, determine the reason in the aspect of programming.To process after careful inspection found that the curve is composed of many small pieces of circular arc, and programming and use the correct positioning check C61 instruction.G61 cancelled from the program, after using G64, eliminate crawl phenomenon.3.5 spare parts replacement method with a good spare parts to replace diagnosed a bad circuit board, which based on the analysis of the general situation of the cause of malfunction, maintenance personnel can use spare copies of the printed circuit board, integrated circuit chip replace the questionable parts or components, thus the fault range narrowed to a printed circuit board or chip level.Initializes the starting, and accordingly make the machine tool quickly into normal operation.For the maintenance of modern numerical control, more and more, this method is adopted to improve the diagnosis and then use the spare parts to replace damaged module, make the system work normally.As much as possible to shorten downtime, pay attention to when using this method in the operation must be under the power status, but also carefully check the PCB version, model is the same, all kinds of tag, jumper, if it cannot be replaced.Stitch should be marked and recorded.Generally don’t change the CPU board, memory board and electricity, otherwise may cause program and the loss of the machine parameters, and extend the fault.Example: a using Siemens SINUMERIK SYSTEM 3 SYSTEM of nc machine tools, the PLC in sichuan and S5 & ndash;130 w\/B, a failure occurs, through the function of PC NC system input parameters R, don’t work in the processing, can not be changed by R parameter values in the program.Through the analysis of the NC system working principle and fault phenomena, think there is something wrong with the PLC of the motherboard, with another machine tools motherboard exchange, further identified as PLC board problem.By the professional factory maintenance, fault be ruled out.3.6 pay * transposition method when found fault board or a can determine whether the board and the absence of spare parts, in the system can be the same or compatible two board swap check, for example, the two coordinate instruction board or the exchange of servo board, to judge from failure board or failure parts.Should pay special attention to the pay * transposition method, not only to the hardware connection of the right to exchange, exchange will bring a series of corresponding parameters, otherwise not only cannot achieve the purpose, it will produce new fault cause confusion, must be considered in advance and good exchange scheme of software and hardware design, accurate exchange check again.Example: a CNC lathe to feed normal X, Z to feed a large, poor accuracy, vibration, noise, using manual and hand pulse feed.Observe the driving plate lamp brightness and change the basic normal, doubt is the Z axis stepper motor and its open circuit or lead the Z axis mechanical failure.Hence the Z axis motor change leads to the X axis, the X axis motor running normally, illustrate the Z axis motor lead normal;And X axis motor change leads to the Z axis, the fault is still;Can conclude that the Z axis motor fault or Z axis mechanical failure.Measure motor fuses, find an open circuit.Repair the stepper motor, troubleshooting.3.7 parameters test system is on the basis of system function, parameter setting error may cause system fault or a function is invalid.