Electrical equipment overhaul paper machine electrical maintenance thesis CNC machine tools electrical maintenance and troubleshooting（电气设备检修论文机床电气维修论

1、Electrical equipment overhaul paper machine electrical maintenance thesis CNC machine tools electrical maintenance and troubleshooting（电气设备检修论文机床电气维修论文数控机床的电气维修与故障的排除）Electrical equipment overhaul paper machine electrical maintenance thesis:Electrical maintenance and trouble elimination of NC machin

2、e toolsAbstract this paper describes the classification of common electrical faults of CNC machine tools, the inspection and analysis methods of electrical faults, the maintenance and troubleshooting of common electrical faults.CNC machine tools; electrical maintenance; failure;With the rapid develo

3、pment of electronic technology and automation technology, the application of numerical control technology is more and more extensive. CNC equipment based on microprocessor and large-scale integrated circuit as a symbol has created conditions for the development of the machinery manufacturing industr

4、y, and has brought great benefits. But at the same time, because of their advanced, complex and intelligent characteristics, the fault diagnosis, maintenance theory, technology and means have undergone leaps and bounds. In this paper, CNC machine tools for electrical maintenance and fault removal ar

5、e briefly discussed.1 Classification of common electrical faultsThe electrical faults of NC machine tools can be classified according to the appearance, nature, cause or consequence of the fault.1.1, to the location of the fault can be divided into hardware and software faults. Hardware fault refers

6、 to the electronic components, wires, cables, printed circuit boards, connectors and other abnormal state, or even damage, which is the need to repair or even replace the fault can be excluded. Software faults generally refer to faults in PLC programs, which require input or modification of certain

7、data and even modifications to the PLC program.1.2, there is no alarm when the fault occurs, divided into diagnostic alarm, fault and no diagnostic alarm fault. The CNC system is designed with self diagnostic procedures, combined with the fault indicator, software and hardware performance of real-ti

8、me monitoring of the whole system, once found fault will immediately alarm or text displayed on the screen, with the diagnostic manual system is equipped with not only to find the reason, the site of the fault, but also excluded prompt method. Machine tool manufacturers will also have specific failu

9、re alarms and diagnostic manuals for specific machine tools. The two parts have the fault of diagnosis and alarm, plus all kinds of alarm lights on each electrical device, which makes most of the electrical faults easier to remove. There is no diagnostic indication of the fault, and it is difficult

10、to remove such faults. We should rely on the work process before and after the failure and the failure phenomenon and consequences, and rely on maintenance personnel to machine tool familiarity and technical level to be analyzed and ruled out.The probability of fault occurrence is divided into syste

11、matic fault and stochastic fault. The fault is divided into destructive and non destructive faults and so on. But in any case, the production of any kind of failure is often mixed, which requires the maintenance personnel to carry out specific analysis of the specific problems, take the appropriate

12、analysis, troubleshooting, and ultimately solve the problem.2 trouble shooting and analysisThis is the first step in troubleshooting and a critical part of it.2.1 work before troubleshooting2. 1.1 inquiry after receiving machine fault site required the exclusion of information, should first try to k

13、eep the site requires the operator to fault state, without any treatment, which is beneficial to the rapid and accurate analysis of the causes of failure. At the same time, carefully inquire about the fault instructions and the background of the fault, and make a preliminary judgment.2., 1.2 on-site

14、 inspection, arrived at the scene, first of all to verify the accuracy of the various circumstances provided by the operator, integrity, so as to verify the accuracy of the initial judgment. Do not rush to handle, carefully investigate various circumstances, so as not to damage the scene, so that tr

15、oubleshooting, increasing the difficulty.2. 、 1.3 failure analysis, according to the known fault conditions, analysis of fault types, so as to determine the principle of troubleshooting. Since most faults are indicated, it is possible to list a wide range of possible causes of the failure, in compar

16、ison with the diagnostic manuals and instructions used in machine tools.2. 1.4 determine the cause of the real cause of this failure to find out several possible reasons in the course may require several tests, this is a comprehensive test of maintenance personnel familiar with the degree and level

17、of knowledge, experience and ability to analyze and judge on the machine.The process of investigation, analysis and diagnosis of common diagnosis methods 2.2 electrical faults of electrical system of CNC machine tool is the troubleshooting process in the troubleshooting period, should make full use

18、of the CNC system self diagnosis function to judge, commonly used diagnostic methods but also flexible use of electrical fault.2., 2.1 intuitive method, this is the initial method of analysis of the fault, that is, the use of sensory inspection.Every part of it is mainly to observe various abnormal

19、phenomena when the fault occurs light, sound and taste by human senses and inspect the system, follow the outside after the first "principle, with hope, smell, touch, ask the method of fault diagnosis, from outside to inside check,The range of faults can often be reduced to one module or a prin

20、ted circuit board. This requires the maintenance personnel to have the rich practical experience, must have the multi-disciplinary broad knowledge and the comprehensive judgment ability.2., 2.2 interface status check method, modern numerical control system integrates PLC among them, and CNC and PLC

21、communicate with each other in a series of interface signal forms. Some of them are wrong or lost and interface signals related to the signal in some of these interfaces can interface board and the corresponding input / output panel lights, some can be through a simple operation on the CRT screen di

22、splay, and interface signals all can use PLC programmer or the corresponding PC. The inspection method requires the maintenance personnel to be familiar with the interface signal of the machine tool and to be familiar with the application of the PLC programmer.2., 2.3 parameter adjustment method is

23、known to all, numerical control parameters can directly affect the performance of CNC machine tools. Numerical control system, PLC and servo drive system are equipped with many modifiable parameters to meet the requirements of different machine tools and different working conditions. These parameter

24、s can not only make the electrical system match the specific machine tools, but also make the functions of the machine tools be optimized. Therefore, it is not allowed to change or even lose any parameters; and the change of mechanical or electrical performance caused by the long-term operation of t

25、he random bed will break the initial matching state and the optimum state. Many of these faults need to be readjusted, and one or more arguments can be excluded. This method is very demanding for maintenance personnel, not only to understand the specific parameters of the system, but also to know it

26、s address and its role, and to have more experience in electrical debugging.2., the 2.4 exchange method of exchange is a simple and easy method. When the fault plate is found or cannot be determined whether the faulty board has no spare parts, the two or the same compatible plates in the system can

27、be checked interchangeably. In the exchange before must pay attention to the template is intact, but the state is consistent, so it is not only the hardware connection to correct exchange, but also will exchange a series of corresponding parameters, otherwise it can not achieve the purpose, it will

28、cause confusion in thinking of new fault, before some consideration, exchange of software and hardware design plan, accurate for exchange check.3 electrical maintenance and trouble shootingThis is the second step in troubleshooting and the implementation phase.Electrical fault analysis process, that

29、 is, the troubleshooting process, this list of several common electrical faults to do a brief introduction, for your reference.3.1 CNC system position ring fault3., 1.1 position ring alarm. It is possible that the position measuring circuit is open; the measuring element is damaged; the position con

30、trol is not established; the interface signal does not exist.3., the 1.2 axis produces motion without instructions. The drift may be too large; the position loop or speed loop is connected to positive feedback; the feedback wiring is open; the measuring element is damaged.3.2 machine coordinate can

31、not find reference pointThe signal returned from the reference point deceleration switch or the zero mark signal is invalid. When diagnosing, we should find out the method first, then compare the fault phenomenon, find the fault location from outside to inside and signal tracking method. Outside may

32、 be zero direction, away from the zero point, check the outside of the machine block and switch, mainly reference point, switch block position is caused by improper configuration, you need to re adjust, you can check the PLC or interface status. The zero mark failure, whether the encoder is damaged

33、or the wiring is open, the zero mark shift of the grating makes the zero return switch fail, and the signal can be checked by the oscilloscope.3.3 accidental downtime. Here are two possible scenarios: one is caused by environmental conditions, such as strong interference (power grids or peripheral e

34、quipment), excessive humidity, and high temperature. The environmental factors are often overlooked by people, such as many machinery factory will put into the common machine tool plant or even near the open door near the cabinet, open the door for a long time, there are a lot of dust, scrap or spra

35、y equipment near; another situation is as before the relevant software design problems caused by downtime in certain operations and functions of the combined general machine tool power after re energized will disappear. These factors will not only cause failure, but also damage the system and machin

36、e tools, and pay attention to improvement.4 example analysis of troubleA XK5040 CNC milling machine in the normal use of the FANUC-3MA system, during operation, the Z shaft produces alarm number 31.4.1 preparation before maintenanceView the maintenance manual, #31 alarm content: error register conte

37、nt is greater than the specified value. Fault characteristic is: Z axis follows error software alarm.Analysis of the phenomenon: following the error is related to the location of the ring, but also because it is driving the Z shaft when the alarm occurs, it can be estimated: large fault location in

38、the Z axis ring. Analysis of closed loop working principle: position loop system,It is a closed loop which consists of the control unit and the drive unit as the main chain and the position detection feedback loop as the sub chain. The principle of closed loop control (see Figure 1):Control command

39、=CNC work instruction - position measurement feedback the actual value, the tolerance is too small, the feedback signal loss will cause the actual feed value is too large, the command value is not normal, can cause super differential alarm. May involve fault types: software faults for machine parame

40、ter settings, and hardware faults in the position loop.4.2, listing the causes of the fault, leading to the establishment of the alarm conditions, there are three possibilities, now using exclusion method to select the most likely causes.4., 2.1 work / control instruction value is too big or too sma

41、ll. It may be that the CNC device or controller is corrupted or disturbed, but the possibility is very small. Can exclude.4., 2.2 allow difference is too small. Possible causes are: A. parameter setting error. This is impossible because the machine tools are not in the commissioning phase. The B. pa

42、rameter has been modified. It may be external interference or memory loss. If the interference results in parameter confusion, then more than one parameter is modified. First, the parameters are checked.4., 2.3 measured value is too small or too large, and the work order is normal. Possible causes:A

43、. feedback signal line instead of "positive feedback", the root with the error is too large. It is impossible because the machine tools are not repaired or debugged.Increase or loss of B. feedback signal. Because the signal line and monitoring system of shielding and grounding is bad, ther

44、e are inductive load interference, sensor loosening and swing, poor installation and so on. It is necessary to check the shielding and grounding of the position detection system, and investigate the environment.The hysteresis of the C. feedback signal results in the measured value of the signal with

45、in 0 of the specified monitoring time. Over a long period of time it is easy to occur on the machine tools, such as pollution of position sensors, damage of signal line, bad contact, position deviation or damage.Therefore, the position detection device, the system and the wiring system thereof shall

46、 be inspected.D. has no feedback signal.A) the sensor is not installed or connected, and the sensor is damaged and does not work. Therefore, the sensor system in the position detection device should be checked.B) the servo unit does not work / the servo shaft does not operate. Analysis and judgment:

47、 the most likely fault type: Hardware failure. The most likely cause of the failure is the location detection system (large fault location) and can not eliminate the environmental interference factors.4.3 determine the diagnostic procedure4. 、 3.1 site work procedure: environment investigation, inte

48、rface signal method, inspection position loop parameter, signal tracking method, check bit system, fault location.Find the normal value of the relevant parameter. Check the maintenance manual for X, Y and Z three axis position loop diagnosis parameter number (address) objects and content and the dia

49、gnosis: three axis corresponding to 800, 801 and 802 state parameters, under normal conditions, they should change in -1 and +1. Field work environment, power grid and appearance survey: no interference source, no power grid fluctuation, no abnormal environment and machine tool appearance.4., 3.2 ch

50、eck the real-time status value of related parameters: after starting the system, the real-time pictures of the related parameters of the parameter settings screen and the diagnostic screen are transferred respectively.Parameter settings screen: parameters do not appear chaotic, indicating no interfe

51、rence and power down. Each servo shaft is pulled by hand, and the state changes of the real-time parameters are observed on the diagnostic screen. It is found that the values of parameters 800 and 801 can be operated by random beds, varying in the normal range, while 802 remain unchanged at 0.Parame

52、ter status comparison: normal / standard / theoretical state values are compared with real-time state values, and only 802 parameters do not change in real time with actions. Large fault location: Z shaft position ring.The signal tracking method is used to check the output before, after, first, afte

53、r the input, then the output.4., 3.3 observation and examinationStart with wiring and sensors. Check: the machine tool Z axis feedback signal line is good. Turn the Z axle motor shaft by hand and carefully listen to the abnormal sound. Suspect position encoder loose.4.4 troubleshooting4., 4.1, fault

54、 check: turn on the Z shaft motor, found that the encoder and the cross between the motor block fall off.4., 4.2 causes of failure: the fixed screw on the encoder is broken, resulting in the Z axis encoder is not connected to the motor, so it does not work without feedback signal. Re connect the encoder properly to troubleshoot.5 Summary of maintenance troubleshootingAfter the troubleshooting,