Generally, tens of thousands of CNC lathes should be economic CNC lathes, which are developed on the basis of ordinary lathes. Its automatic control system is mainly composed of single-chip microcomputer. Through the control program, it controls the longitudinal and transverse feeding devices and tool changing devices of the machine tool, and automatically completes the processing of parts. Economic CNC lathes are also called small CNC lathes. Therefore, small CNC lathes are still electromechanical equipment. Therefore, in case of failure, it is also necessary to comprehensively analyze the mechanical structure and electrical control of the machine tool.10 common issues encountered by CNC Lathe machine tools in processing 2

10 common issues encountered by CNC Lathe machine tools in processing 3

1. When the CNC lathe program is running, the workbench suddenly stops

This phenomenon is generally caused by mechanical failure, but it may also be caused by the failure of the control system. At this time, you can first return the workbench to the original point and restart the processing program. If the workbench always stops when it runs to a certain position, it should be that a part of the transmission system is damaged, deformed or stuck by foreign matters. First, cut off the power, and then check whether the gap between the screw nut and the screw or the slide plate insert is too tight, whether there is foreign matter in the ball guide groove of the ball screw, whether the screw is bent and deformed, whether the flexible gear in the stepper motor reducer is loose or foreign matter is stuck, etc. If the manual barring is normal, it is the control system fault, and it should be checked according to fault 1.

2. The stepping motor jitters and does not rotate after the program runs

This phenomenon is generally caused by the open phase of the stepping motor or its control system. It may be the fault of the stepping motor itself or its driving circuit. First, check whether the connection plug of the stepping motor is in good contact. If it is in good contact, replace the motor without fault to verify whether the motor is in good condition. If the motor still cannot work normally after being replaced, it indicates that its control part is abnormal. You can mainly check the high-power triode and its protective element release diode on the drive board. Generally, these two elements

3. The CNC LATHE is offside when it returns to zero

Generally, it is caused by too much running resistance of mechanical transmission system. During cutting feed, the tool holder runs at low speed, driven by low voltage, and the running torque of the stepping motor is small, which is not enough to overcome the resistance and cause step loss. When returning to zero, the stepping motor is driven by high voltage, with high running speed, large torque, and no cutting resistance, so the stepping motor does not lose step. In this way, if you lose your step when you go and return to normal, you will not return to zero. At this time, you can check whether there are iron filings and foreign matters on the transmission gear in the stepper motor reduction box or between the stepper motor and the lead screw, or whether the slide insert is too tight to increase the running resistance, etc.

4 step loss of stepping motor at high speed ON cnc LATHE

It may be that the driving power supply voltage decreases, which reduces the output torque of the stepping motor. The driving power supply shall be mainly checked. When the high-voltage switch triode is damaged, the high-voltage power supply Tianfa is connected, and the stepping motor output torque is reduced and the step is lost at high speed. There may also be a mechanical failure somewhere, so you should also check the lead screw, nut, slide plate, stepping motor reducer, etc. When there are parts bent, deformed, or foreign objects, the running resistance will increase. The phenomenon is not obvious at low speed, but it cannot completely overcome the running resistance at high speed.

10 common issues encountered by CNC Lathe machine tools in processing 4

5. The CNC LATHE does not return to zero after the program runs

Generally, the control system fails. When the tool is feeding or processing, the running speed of the stepping motor is low, and when the program returns to zero, it is required to return quickly. The stepping motor runs at high speed and adopts high-voltage driving power supply to increase the output torque. There is a switch triode that controls the output of the high-voltage drive power supply. When the switch triode is damaged, the high-voltage power supply cannot be turned on when the high-speed return to zero, and the output torque of the stepping motor is not enough, resulting in the tool not returning to zero. It can be eliminated by replacing the switch triode.

6. The size error of the processed workpiece is very large

One possibility is that the connection between the lead screw or nut and the lathe is loose. When idling, there is no cutting resistance, and the slide plate operates normally. During processing, due to the increase of cutting resistance, the connection between the lead screw or nut and the lathe is loose, resulting in the size drift of the processed workpiece. Fasten the connecting part, and the fault can be eliminated. Another possibility is caused by electric knife rest. If the tool holder cannot be locked automatically after changing the tool, and the tool deviates from the machining point during cutting, the above phenomenon will also be caused. At this time, check the tool holder locking device and tool holder control box.

7. Return to the monitoring state and stop the work during the program execution

It is generally caused by the failure of the monitoring program or strong magnetic interference. Strong magnetic interference can be solved by grounding or shielding. If the program is not executed or the execution instruction is not followed when starting the program, the monitoring state will be returned immediately. Generally, the monitoring program or computer hardware has a fault, and the suspicious chip can be replaced, such as the off chip program memory chip, the programmable interface chip or the single chip microcomputer itself. Sometimes the failure of off chip data memory can also cause this phenomenon. Otherwise, we have to find the manufacturer to debug again.

8. The electric tool holder cannot be positioned and rotates continuously when changing tools

This is because when the program wants a certain tool, the electric tool holder is turning to select the tool. When it rotates to this tool, there is no response signal, so the tool holder rotates more than once and cannot be positioned. The hall element on the electric tool holder should be checked. When the hall element is damaged, the signal output will not be detected when the required tool is in place, resulting in the above phenomenon. Replace the hall element of this knife.

9. The local dimension error of the workpiece is large

It is mainly caused by the excessive gap between the screw nut and the lead screw. Because the lead nut and lead screw operate in a certain section for a long time, the gap of this section is increased. At the beginning of the program, the measured lead screw clearance is compensated into the program, but it cannot be compensated in the wear section, so that the local dimension of the workpiece is out of tolerance. The solution is to repair or replace the lead screw.

10. The processing program is often lost

If the machining program is lost after the control system is powered off, and the machining program is re entered after the machine tool is powered on, and the machine tool can process normally, the backup battery voltage may be reduced or disconnected, resulting in the loss of the machining program in the data memory after the machine tool is powered off. Replace the backup battery. If the processing program is often partially or completely lost in the processing process, it is very likely that the data memory is faulty. At this time, the off chip data memory or the single chip microcomputer itself can be replaced.

The above is our summary of 10 common processing problems of the equipment under the price of various CNC lathes.

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