High Speed Machining Center Daily Failure Analysis

- Sep 07, 2017-

Daily failure analysis of high speed machining center

According to the breakdown of nc machine tool

1. Failure of the main engine: the main engine of the high-speed machining center refers to the mechanical, lubrication, cooling, cutting, hydraulic, pneumatic and protective parts of the high-speed machining center. Main engine failures are:

1. Malfunction caused by interference of motor components such as guide rail, spindle, etc

2. Faults caused by the damage of mechanical parts, bad connections, etc.

The main fault of main engine is the transmission noise, poor machining accuracy, large running resistance, no movement of mechanical parts, damage of mechanical parts, etc. Poor lubrication, hydraulic, and pneumatic systems are clogged and badly sealed, which is a common cause of engine failure. Regular maintenance and maintenance of high speed machining center. Controlling and eradicating the "three leakage" phenomenon is an important measure to reduce the failure of host parts

3. Mechanical transmission failure due to improper installation, commissioning and improper operation of mechanical parts

The electrical control system fails from the type of component used. According to general habits, the failure of the electrical control system is usually divided into "weak current" failure and "strong power" failure.

The "weak power" part refers to the control system mainly controlled by electronic components and integrated circuits in the control system. The weak current in the high speed machining center includes CNC, PLC, MDI/C RT and servo drive unit and output unit.

The "weak power" fault has hardware failure and software fault. Hardware failure refers to the failure of the integrated circuit chip, discrete electronic components, connectors and external connection components. Software failure refers to the failure of germanium and data loss in the normal operation of hardware. Error, change or loss of system procedures and parameters, error of computer operation, etc.

"High voltage" part refers to the primary circuit in the control system or high voltage, high power circuit of relay, contactor, switch, fuse, power transformers, motors, electromagnet, travel switch of electric components and its control circuit. This part of the fault is convenient for maintenance and diagnosis, but because it is in high voltage and large current working condition, the probability of failure is higher than the "weak power" part. Adequate attention must be paid to the maintenance staff.

3. Classified according to the nature of the fault

1. Deterministic fault deterministic fault refers to the failure of hardware damage in the control system or the inevitable failure of high speed machining center as long as certain conditions are met. This kind of fault phenomenon is most common in high speed machining center, but because it has certain rules, it also brings convenience to maintenance

The deterministic fault is not recoverable. Once the fault occurs, if it is not repaired, the machine will not automatically return to normal. But as long as the root cause of the failure is found, the machine can return to normal immediately after maintenance. Proper use and careful maintenance are important measures to prevent or avoid failure.

2 random fault random fault is refers to the high speed machining center in the working process of the accidental fault such failure reason is hidden, it is difficult to find out its regularity, reason often referred to as "soft" failures, the reason of random fault analysis and fault diagnosis is difficult, in general, the occurrence of failure often with parts installation quality, parameter setting, the quality of the components, software design is not perfect, the influence of the working environment, and many other factors.

The random faults can be recoverable. After the failure, the machine can normally return to normal, but the same failure can occur during operation.

Strengthen the maintenance inspection of CNC system, ensure the sealing of electrical box, reliable installation, connection, correct grounding and shielding are important measures to reduce and avoid such failures.

4. Classified according to the breakdown of the instructions

The fault display of the fault high speed machining center shown in the paper can be divided into indicator light display and display display two situations:

1) the indicator light shows that the alarm refers to the alarm that is displayed by the status indicator on each unit of the control system (usually composed of LED light tubes or small indicators). According to the status indicator of the numerical control system, even when the monitor fails, the location and nature of the fault can be analyzed in general. In the process of maintenance and troubleshooting, the status of these status indicators should be carefully checked.

2) monitor display alarm. The monitor display alarm refers to the alarm that can display alarm number and alarm information by CNC display. Because the numerical control system is generally strong self-diagnosis function, if the diagnosis software of the system and display circuit work normally, once the system failure, alarm number on the screen and display fault information in the form of text. The numerical control system can display the alarm of dozens, many thousands, it is the important information of fault diagnosis.

In the display display alarm, it can be divided into NC alarm and PLC. The former is the numerical control manufacturer's setting for the reason drop display. It can control the system's "maintenance manual" to determine the cause of the failure. The latter is the PLC alarm information text set by the manufacturer of high speed machining center. It can control the relevant contents of "machine tool maintenance manual" provided by machine tool manufacturers. Determine the cause of the failure.

In the event of failure of the alarm display. The machine tool and the system are not alarm display, its analysis diagnosis difficulty is usually bigger. It takes careful and careful analysis to make sure. Especially for some early numerical control systems, because the diagnostic function of the system itself is not strong, or there is no PLC alarm information text, the failure of the alarm display is more.

In case of no alarm display failure, it is usually required to analyze the specific situation, according to the changes before and after the failure. Analysis and judgment, principle analysis and PLC program analysis are the main methods to solve the failure of alarm display.

4. Classification of the causes of failure

The fault of the high speed machining center is caused by the high speed machining center itself, which has nothing to do with the external environment. Most of the faults occurred in high speed machining centers.

The external fault of the high speed machining center is caused by external causes. The power supply voltage is too low, too high, excessive fluctuation: the power phase sequence is incorrect or the three-phase input voltage imbalance; Environmental temperature is too high: harmful gas, moisture and dust are brought in: external vibration and interference are the causes of failure.

In addition, the human factor is one of the external cause of the high speed machining center fault, according to the statistics, for the first time the use of high speed machining center or by unskilled workers to operate, high speed machining center in the first year of use, improper operation caused by the external failure to account for more than a third of total machine tool failure.

In addition to the above common fault classification methods, there are many different classification methods. Failure is not destructive when it occurs. It can be divided into two types: destructive failure and non-destructive failure. According to the breakdown and the specific function of maintenance. It can be divided into nc device fault, feed servo system failure, spindle drive system failure, and white movable knife system fault, etc. This classification method is often used in maintenance.

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