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This article introduces the faults that occur due to improper parameter settings when using the Mitsubishi CNC system and the methods for troubleshooting, which can be used as a reference for debugging and maintenance engineers and operators.
     1. “S01 2236 X” alarm
     (1) Fault phenomenon: An automatic production line for automobile parts is equipped with Mitsubishi's latest C70 CNC system. When debugging it, alarm #2236 occurred. The content of the alarm is that the parameter settings of the X-axis "power regeneration module" are incorrect.
     (2) Analysis and processing After checking, the parameter settings are correct.
     The principle of #2236 parameter setting is to only set relevant parameters on the last axis connected to the "power regeneration module", and do not set this parameter for other axes (take the default value).
     When I carefully checked the hardware connection, I found that the connection between the servo drive and the "power regeneration module" was incorrect. The CN4 of the power regeneration module should be connected to the CN4 port of the last servo axis (or spindle). When a fault occurs, the CN4 port of the power regeneration module is connected to the first axis (the drives are not arranged in order), so no matter how it is set The parameters all report the "#2236" error. This alarm is eliminated after correct connection.
     This is a case where the alarm is "parameter setting error" but it is actually a connection error. However, troubleshooting still needs to start from factors related to the parameter.
     2. Soft limit failure
     (1) Fault phenomenon The CNC lathe is equipped with the Mitsubishi E60 system. Set the X-axis of the lathe to the diameter axis (#1019=1), set the soft limit with parameters #2013 and #2014, and jog the X-axis. When the X-axis value displayed on the screen exceeds the soft limit value, the X-axis can still run, and it seems that the soft limit has failed.
     (2) Observation and analysis On the same machine tool, the soft limit of one axis is valid, but the other axis seems to be invalid. The difference is that one axis of the lathe is set to the diameter axis.
     It turns out that the value of the diameter axis displayed on the display is the diameter value, and the actual moving value is only half of the displayed value. Therefore, when the screen shows that the X-axis travel has exceeded the soft limit, the actual travel has not exceeded the soft limit, so the X-axis Still works.
     To ensure safety, you should first set the X-axis #1019=0, then use the hand wheel to run the Set X-axis parameter #1019=1.
     You cannot set X-axis parameter #1019 = 1 first, and then set the soft limit value based on the screen display value. If the soft limit is set in this order, the soft limit will be twice as large as the safe travel, which of course will not provide protection.
     3. Pitch compensation is invalid
     (1) Fault phenomenon Pitch compensation is invalid. A customer always reports that it is invalid when performing mechanical precision pitch compensation.
     (2) Observation and analysis The parameters related to mechanical accuracy compensation in the Mitsubishi CNC system are a set of parameters after #4000.
     The misleading one is #4007. This parameter determines the length between each measurement point, and its setting unit is 1/1 000mm.
     Generally, when doing accuracy compensation, the measurement interval is 50mm. Some customers often set #4007 = 50 (which is equivalent to a measurement interval of 50/1 000mm). In this way, even if the error of each point is measured using a laser interferometer, the compensation If the position is wrong, it still looks invalid, but it is actually compensating for the wrong position.
     Set #4007 = 50 000, then the measurement point spacing = 50mm. Use a laser interferometer to measure the error at each point, and you can perform correct compensation.
     In addition, some customers reported that the "mechanical accuracy error" of their milling machines was greater than 300 μm when measured with a laser interferometer, but the setting range of Mitsubishi CNC related compensation parameter #4101 is -128 ~ -127 μm. How to set the compensation amount?
     In fact, in the mechanical accuracy compensation parameters of Mitsubishi CNC, "compensation amount = set value × compensation magnification". #4006 is the compensation magnification, generally set to #4006=1. If the compensation value is too large, the setting value of parameter #4006 must be increased. By setting the magnification parameter #4006, even a large "error value" can be corrected. compensate.
     The compensation function of Mitsubishi CNC is powerful. After compensation, the system accuracy can reach 0.000 1mm.
     4. Screen display value failure
     (1) Basic configuration: CNC lathe equipped with Mitsubishi M64AS system.
     (2) Fault phenomenon: The value displayed on the screen is greater than the actual value; when doing equipment modification for a customer, the value displayed on the screen is greater than the actual value.
     (3) Analysis and Observation Factors related to this phenomenon are as follows:
     ① Motor gear ratio and mechanical gear ratio. ②The pitch of moving parts. ③ The mechanical connection part slips.
     At that time, the customer's equipment was old equipment purchased, and the reduction ratio of the gearbox could not be found. The kinematic pair was a rack and pinion.
     Among the relevant parameters of Mitsubishi CNC servo motor:
     #2201=Motor end gear ratio #2202=Mechanical end gear ratio #2218=Pitch Since the gearbox reduction ratio cannot be found, the customer cannot provide it, so the gear ratio can only be measured through experiments. The test methods used by the author are as follows:
     First set #2201=1, #2202=1 (equivalent to 1:1 connection), and pitch #2208=10mm (equivalent to using a 10mm pitch screw).
     Continuously issue positioning instructions of 1000mm, 2000mm, and 3000mm, and measure the corresponding actual values. Assume that the command value = L1 and the actual value = L2, then the gear ratio of the reduction box = L1/L2. Repeat the measurement 10 times and take the integer value. Just set #2202=L1/L2.
     Of course, the sliding of the mechanical part is a factor causing the above phenomenon, which should be eliminated from the beginning.
     For the renovation of old equipment, this is a method when there is insufficient data.
     5. “Data Protection” appears on M64AS system
     (1) Fault phenomenon The machining center is equipped with Mitsubishi M64AS system. After the user randomly sets data to the parameters after #4000 many times, the following situation occurs: "Data protection" message appears when setting parameters.
     Check #1222 bit3=1 - parameter locking is valid (#1222 itself cannot be modified at this time).
     (2) Troubleshooting On the I/F diagnostic screen, forcefully set R1860 =1, which releases the "parameter lock".
     6. Communication failure caused by #6451 parameter setting
     (1) Basic configuration The heat treatment machine tool is equipped with Mitsubishi E60 CNC system.
     (2) Fault phenomena ① The fault phenomena reported by customers are as follows:
     The PLC program was interrupted midway. After the power was cut off, #6451=00110000 was reset and the screen immediately turned gray. Only by setting #6451=00010000, the screen returns to normal. After the system is repaired and formatted, the system screen can operate normally again. After setting #6451=00110000 again, the system turns to gray screen again. ②The fault phenomenon reported by the customer is as follows: the CNC system is E60. During initial debugging, after setting #6451=00110000, the system becomes a gray screen.
     Both of the above examples are related to parameter #6451.
     (3) Fault analysis In the Mitsubishi CNC system, #6451 is used to specify PLC program transmission to the CNC system. If #6451=00110000 (bit5=1) is set, it will enter the GX communication state, that is, Mitsubishi's dedicated programming software "GX-DEVELOP"
     The developed PLC program is sent to the CNC system.
     If #6451=00010000 (bit5=0) is set, RS232 communication will be entered. Used to transmit parameters, processing programs, etc.
     In this example, once #6451=00110000 is set, a gray screen appears. Even after repair and formatting, the fault cannot be eliminated.
     This fault is related to PLC communication, or the communication error may be caused by the PLC program that does not comply with the format.
     (4) Troubleshooting Set the NC system knob = 1 to stop the PLC program and eliminate the influence of the PLC program. Set #6451=00110000 again. At this time, no gray screen appears. After transferring the normal PLC program, the system is normal.
     In the first case, after transferring the original PLC program to the system, it was observed that the dialog window of the GX software had "PLC program alarm information". This was the first time that this phenomenon was observed. After formatting the PLC program, then transfer the normal program and the system will be normal.