Alarm 20000 (Channel 1 axis WZM reference cam not reached)
The alarm can be generally understood as the tool magazine failed to return to reference point (for details see SINUMERIK 840D/840Di/810D/FM-NC Description of Functions Basic Machine，FB1，Reference Point Approach). It’s easy to find problems with a roughly check to the reference point device. In this case, the broken connection was found to the proximity switch S32.3. And the alarm disappeared after welding.
Poor automatic tool change, with loud noise.
With method “grabbing empty tool” can observe relative position of tool changer and taper of spindle. Found the position of spindle was slightly lower. By adjusting the MD34090 parameter of Y axis (REFP_MOVE_DIST_CORR, in the menu Start-up/Machine data/Axis specific) can raise its position. In this case adjusted it from -96.403 to -93. After resetting NCK the tool change was basically normal.
Alarm 700126 (Com bit set)
Reinstalled PLC and the alarm disappeared.
Alarm 700000-799999 is an alarm of user area of PLC. Usually you could not find the relevant information to them in the documents provided by the machine tool builder. Then the accumulation of experience is particularly important.
Alarm Magazine Position/Gripper Empty. Could not change tool.
Put a tool on the current gripper.
The process of the tool exchange was interrupted accidentally and the tool on the spindle was stuck on the gripper of the tool magazine.
After restart the axes of the machine still could not be moved.
In the menu Deckel Maho/Manual control/Tool change, Pressed a key by graphic (right one) and heard and saw the gripper was released. Pressed the red emergency stop push button to make off the drives’ power. Turned the lead screw with hand to make the spindle and cutter out of the tool change area.
Turned off and on the machine. Reinstalled PLC. Restarted the machine. Made the axis X return to the reference point. At this moment the small door for tool change closed automatically and the machine restored to normal.
When the X coordinate was zero, the axes of the spindle and the rotary table were not coplanar, and the rotary table could not be used for precise machining.
Fixed two fixtures on the rotary table, as shown in the picture. While the rotary table turned to 0° or the B axis was in 0° position, made them parallel to the Z axis with a dial gauge. Found the center coordinate between the two fixtures through touching, reading and calculation:
while B=0°, X=-151.010;
while B=180°, X= 151.236.
Then:
151.236-(-151.010)=302.246
302.246/2=151.123
151.236-151.123=0.113
Added this 0.113 to the value of the 34090# parameter (REFP_MOVE_DIST_CORR[0], 456.977+0.113=457.090) and restarted the machine. Found the situation was improved.
The difference between the absolute values of the positive and negative X could be very small when the process is repeated. Finally it was 5μ in this example.
The alarm appears more frequently. Sometimes it disappears by itself, but sometimes it takes a lot of twists and turns. If it is troublesome, can deal with it according to the following procedures:
1. Following the pallet exchange process(see “Alarm 700101+ and oil spill from rotary table”), manually poke the solenoid valve to fulfil each step in sequence. Make a moderate effort to make the lamp light. Can observe the PLC status on the screen to make sure that it is in place. Considering safer, you can poke a valve with another person observing. Press the emergency stop in case of emergency. Can also unload the pallets in advance. This procedure can generally eliminate alarms.
2. If the alarm still exists, reinstall the PLC. If the small door for tool exchange is not closed, can perform manually axis X return to the reference point. After that the door will fall automatically.
Here are two examples.
Fault:
Alarm: 700112 Pallet changer not in basic position.
Remedy:
Following the pallet exchange process found E36.4(pallet changer in 0° position) and E36.5(pallet changer in 180° position) were both “0”. Turned in clockwise a little bit the proximity switch and cable corresponding to E36.5. Orange light and yellow green light were lit at the same time. Restart the machine, the alarm was eliminated.
Fault:
The machining process was interrupted randomly by the alarm 700112. Normal after shutdown and restart. Sometimes the frequency is nearly 1 times per hour.
Remedy:
Following the pallet exchange process, checked PLC status and found that E36.2(Pallet clamped on rotary table) was changed from “1” to “0” when the alarm appeared, and E36.3(Pallet unclamped on rotary table) was always 0″.
A40.2 was “1”, indicating that the system had given the locking signal, the solenoid valve Y40.2 indicator light had been lit, but the corresponding pressure switch S36.2 may not give a signal, making E36.2 become “0”.
Checked and replaced S36.2, the alarm was completely eliminated.
System 840D had run up and basic screen appeared. But the drives could not be on. There was an alarm: Stop No Mode Group Ready.
There is description about Mode Group on the operating manual of 840D. This machine only has one mode group. The alarm can be thought of as the machine is not ready.
While checking, the machine went well sometimes, but bad in other times, irregularly. When pressing the push button Drives On (S45.6) found the status of E45.6 (on the display of console) changed to “1” from “0”. It showed that the PLC had received the signal sent by the push button through the emergency stop circuit.
According to the electrical schematic diagrams, holding down the button Drives On and checking voltages with a multi-meter, found that there was a 24V voltage of the pin 21 of the relay K17 (page 218) relative to the pin A2 of the relay A170. But pin 22 not. So doubted K17 malfunction. Exchanged K17 and K9 (the same model, optional, not used in this machine) and tried. The machine restored to normal.
Alarm 700101: Set-up station not moved to 0 degree or not fixed.
Checked I/O status on control console and found E45.7 being ‘0’. After further check S45.7 was found malfunctioning. Replaced it and the machine returned to normal.