Analysis of Failures of NC Gantry Boring and Milling Machine NCXT2025

Our factory NCXT2025 CNC gantry boring and milling machine adopts FANUC 6M system, spindle adopts Japanese DL-SDZ-2F-3FK DC speed control system, and external Omron C500 programmable controller. This machine tool is one of the most advanced large-scale CNC machine tools at the end of the 1980s. Example 1

Figure 1 motion preparation circuit

Figure 2 MA control section and power supply

Figure 3 Ladder Diagram

Fault phenomenon: When the machine is powered on, the screen shows: FANUC SYSTEM 6M MODEL B SERIES MA3 UERS15 NOT READY Fault Cause Analysis: NOT READY means that the control device or servo system is not ready. Under normal circumstances, the probability that the servo system is not ready is quite high, and the control device is not particularly prepared. For this reason, to eliminate this fault, check the servo system and check the control device. When using the PC programmer to check the control device, you can achieve a multiplier effect. Troubleshooting steps : (1) Full inspection and inspection of the 6M system's servo system, no obvious abnormalities were found. (2) Check the control device part. The motion preparation circuit is shown in Fig. 1. The voltage between terminal 1 and terminal 2 is 110V measured with the multimeter 250V AC. When the start button PB3 is pressed, the voltage between the measuring point 3013 and the terminal 2 is also 110V, and the voltage between the point 3014 and the terminal 2 is 0V, which means that the contact of the small relay MA is not turned on. Measured with a multimeter DC 50V (see Figure 2) The voltage between the 3035 terminal and the regulated power supply terminal 4 is 12V, normal corresponds to 24V, significantly lower. The DC voltage at terminals 3 and 4 is again 12V. Remove the load of the regulated power supply and measure the no-load voltage as 24V. Normally, it is suspected that the power supply has a reduced load capacity. Replace the original regulated power supply with another 24V-5A DC regulated power supply. Test the machine and everything is normal. Examples of two Symptom: Y-axis manual, automatic feed normal negative direction, and the positive direction is not fed. Analysis of the cause of the failure : To analyze the cause of this failure, it must be combined with the relevant ladder diagram (Figure 3). Troubleshooting steps: ( 1) Plug the PC programmable controller into the PC programmer interface, and put the status switch on the programmer in the MONITOR state, press the CLR button and the MONTR button, and then press CLR, OUT and 1, 3, 0, 2 number keys, display: 0000 OUT 1302
Then press the MONTR button to monitor its status: 1302 NO
Description 1302 relay coil is switched on. (2) The voltage between the multimeter's 50V DC output terminal 1302 output terminal and the stabilized voltage supply terminal 4 is 0V, and the voltage between the output terminal of 1302 and the voltage stabilized power supply terminal 3 is also 0V, and it can be seen that the output relay of 1302 is bad. . Replacing the original PC internal output relay with one of the same type of relay, everything returned to normal. Three examples Symptom: When the spindle speed, frequent stalling phenomenon. Analysis of failure causes: To eliminate such failures, we must start from the following two aspects: (1) DC system itself: (2) Control the external circuit part of the DC system. In accordance with the principle of easy-to-follow, first check the outside of the system, and then check the system itself. Troubleshooting steps: First check the components of the ladder diagram in Figure 3. According to the indicator light on the PC, when the spindle is stopped at high speed, 306 in Figure 3 is powered off. Replaced with a switch of the same type, power test machine, troubleshooting, operation for several months, everything is normal.