CNC lathe failure problem

CNC lathe is one of the widely used CNC machine tools. It is mainly used for cutting and processing of inner and outer cylindrical surfaces of shaft parts or disc parts, inner and outer conical surfaces with arbitrary conical angles, complex rotating inner and outer curved surfaces, cylinders, conical threads, etc., and can perform groove cutting, drilling, reaming, reaming and boring. CNC lathe failures can be divided into mechanical failures and electrical failures. Let’s learn more about it below!

(1) Mechanical failure

This type of failure mainly occurs in the main machine part, and can also be divided into mechanical component failures, hydraulic system failures, pneumatic system failures and lubrication system failures.

For example, an alarm appears when a CNC quenching machine is started back to the reference point and moved along the X-axis. This alarm also appears when manually moving along the X-axis. When checking the servo device, an overload alarm indication was found. According to Siemens' instructions, the fault may be caused by excessive mechanical load, servo control power problems, servo motor failure, etc. Based on the principle of mechanical and electrical , detect the X-axis slide table and manually move the X-axis slide table. I found it was very heavy and the disc did not move, which means there was a problem with the mechanical part. Remove the X-axis ball screw for inspection and found that the ball screw is rusty. It turned out that the sliding table was not sealed well, and the quenching liquid entered the ball screw, causing the ball screw to rust. The ball screw has been replaced with a new one, troubleshooting.

(2) Electrical failure

CNC lathe manufacturer said that electrical failure refers to failures of the electrical control system, mainly including failures of CNC devices, PLC controllers, servo units, CRT displays, power modules, machine tool control components, detection switches, etc. This part of the fault is a common fault of CNC machine tools and should be taken seriously.

According to whether there is an alarm display after the fault occurs, it is divided into two categories: an alarm display fault and an alarm display fault without alarm display fault.

This type of fault can be divided into hardware alarm display and software alarm display.

1) Hardware alarm display fault. Hardware alarm display usually refers to the alarm indication of indicator lights on each unit device. In CNC systems, there are many indicators to indicate the fault location, such as control system operation panel, CPU motherboard, servo control unit and other components. Once these indicator lights of the CNC system indicate the fault status, the location and nature of the fault can be roughly judged based on the alarm meaning of the indicator lights on the corresponding parts, which will undoubtedly bring great benefits to fault analysis and diagnosis. Therefore, maintenance personnel should pay attention to check whether these indicator lights are in normal state during daily maintenance and troubleshooting.

2) Software alarm display fault. Software alarm display usually indicates the alarm number and information displayed on the monitor of the CNC system. Since the CNC system has a self-diagnosis function, once a fault is detected, it will be processed according to the level of the fault and the alarm number and information will be displayed on the monitor.