Common Faults and Treatment of Simple CNC Lathe(2)

6. The size of the processed workpiece has a large error

One possibility is that the screw or nut is loosely connected to the lathe. There is no tool resistance during idling, and the slide plate is operating normally. Due to the increase in cutting resistance during processing, the connection between the lead screw or nut and the lathe becomes loose, resulting in a drift of the workpiece size. Tighten the connection part, the fault can be eliminated. Another possibility is the formation of an electric tool post. If the tool holder cannot be actively locked after the tool is changed, the tool deviates from the machining point during cutting, which will also cause the above phenomenon. At this time, check the knife holder locking device and the knife holder control box.

7. Large size error of workpiece part

It is mainly caused by the excessively large gap between the nut and the screw. Because the screw nut and the lead screw work in a certain section for a long time, the gap in this section is increased. At the beginning of the program, the measured lead screw gap is compensated into the program, but it cannot be compensated in the wear section, which causes the part dimension of the workpiece to be out of tolerance. The solution is to repair or replace the lead screw.

8. The electric tool post cannot be positioned and rotated when changing tools

This is because when the program asks for a certain tool, the electric tool post is transferring the tool. When the tool is rotated to the tool, there is no response signal, and the tool post rotates continuously and cannot be positioned. The Hall element on the electric tool post should be checked. When the Hall element is damaged, the signal output will not be detected when the tool is in place, and the above phenomenon will be formed. Just replace the Hall element of the knife.

9. Return to monitoring status during program execution and job abort

It is usually caused by a fault in the monitoring program or strong magnetic interference. Grounding or shielding can be used to deal with strong magnetic disturbance. If you do not execute the program or execute the instruction when you start the program, you will immediately return to the monitoring state. Generally, there is a problem with the monitoring program or computer hardware. Suspicious chips can be replaced, such as off-chip program memory chips, programmable interface chips, or the microcontroller itself. Sometimes an off-chip data storage failure can also cause this phenomenon. Otherwise, I have to find the manufacturer to debug from scratch.

10. Processing procedures are often lost

If the processing program is lost after the control system is powered off, and the processing program is input from the beginning after the machine is powered on, the machine can process normally, it may be that the backup battery voltage is reduced or disconnected, and the processing program in the data memory cannot be maintained after the machine is powered off And lost. Just replace the spare battery. If the processing program is often partly or completely lost during processing, it is most likely that the data memory is faulty. At this time, the off-chip data memory or the single-chip microcomputer itself can be replaced.

In short, a simple CNC lathe consists of two parts: mechanical and electrical. After a fault occurs, it must be analyzed from both mechanical and electrical aspects to determine whether it is a mechanical fault or an electrical fault, and then in-depth analysis to find the fault.