How to deal with the faults of CNC gantry boring a

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How to deal with the fault of CNC gantry boring and milling machine

[Abstract]: xk2414 × The fault analysis and treatment methods of 80 CNC gantry boring and milling machine under working conditions

I. Introduction to machine tool

xk2414 × The type 80 CNC gantry boring and milling machine uses the Siemens 840D CNC system and SIMODRIVE 611D digital drive. The workbench (x-axis) adopts the linear guide technology and full closed-loop control mode. The mechanical transmission structure is double gear teeth. The position detection uses Heidenhain lb382c grating ruler. The minimum resolution is 0.001 mm. There is a zero point mark every 200mm. The total length of the workbench bed is 16.5m, and two sections are spliced

II. Fault phenomenon

when the machine tool is powered on and debugged for the first time after relocation, the CNC system starts normally, and the machine tool drive is powered on normally. Under the ref operation mode, the Y and Z axes return to zero normally, but the X axis of the machine tool cannot complete the zero action. The machine tool stops moving after moving 200mm in the x+ direction, and the machine tool alarms No. 20002: the x-axis zero reference mark of channel 1 is not found

III. fault analysis

check the machine tool data 34060 refp Max markerdist (defines the maximum distance between the trigger start and the following zero mark). The original setting value is 200. Theoretically, the x-axis must pass the zero mark every 200mm of movement. Modify the machine tool data 34060 to 300 to ensure that there is a zero mark within the distance of movement when the x-axis returns to zero. The fault is not removed. Under the jog operation mode, the X, y and Z axes can jog normally, The laser detects the positioning accuracy and resetting of the x-axis, but the electric vehicle will have more and more position accuracy within the allowable range of the machine tool. In the auto operation mode, the processing program cannot run. After modifying the machine tool data 20700 from 0 to 1 (it is defined that the machine tool can automatically cycle the processing program without returning to zero), the processing program can run automatically, but the workpiece coordinates established by the machine tool using the G code (g54~g59) are incorrect, and other functions of the machine tool are normal. Through the above inspections and tests, it is preliminarily determined that the reason for the x-axis zeroing fault of the machine tool is that the zero mark was damaged when the grating ruler belt was pulled out of the grating ruler box and reinstalled during the relocation of the machine tool

IV. troubleshooting

check the grating tape and find that there are oil stains and scratches on the grating tape. After cleaning, the fault cannot be eliminated, and the physical damage of the grating tape cannot be repaired. In order to put the machine tool into production as soon as possible (it takes 1-3 months to order the new grating ruler), it is decided to change the x-axis into a semi closed loop, and use the feedback information of the built-in encoder of the x-axis servo motor as the position loop. The method of changing the full closed loop into a semi closed loop is as follows

1. modify the data of No. 34200 machine tool of X axis (from 3 to 1), and change the zeroing mode of X axis to the zeroing mode with limit striker

2. Make and install the mechanical impact block, add a zero return limit travel switch, adjust the position of the limit travel switch and the mechanical impact block, and connect the input signal of the limit travel switch to the DMP input module of PLC

3. use STEP7 software to modify the PLC program, read and process the input signal of the limit travel switch, and change the effective second measurement system to the effective first measurement system. Use STEP7 software to modify fc30 function block as follows

m009: s m59.1 (x-axis feeding is enabled, and the machine tool is ready to return to zero)

a 137.7 (read the input signal of the limit travel switch) = x12.7 (start looking for the zero pulse signal)

r × 2.1

R × 21.7

R × 1.6 (the second measurement system is invalid)

s × 1.5 (the first measurement system is valid)

4. modify the data of 32700 machine tool of x-axis (from 1 to 0), cancel the pitch error compensation of x-axis (only required in full closed loop), measure the reverse direction of x-axis, find out the problem gap of any accessories of the experimental machine and compensate it, and find out where the manufacturing industry will face important opportunities in the future, and put it into the back flash (0) of x-axis

5. adjust the relevant machine tool data of the x-axis, reduce the system inspection accuracy of the x-axis, adjust the 364 of the x-axis to the emerging 00 contour tol data value of China's biofuel granulator industry from the original 0.02 to 0.03, and adjust the 36030 stand still POS tol data value of the x-axis from the original 0.02 to 0.03, Eliminate the two alarms of the system 25050 (axis X1 con tour monitoring) and 25040 (axis X1 standstill monitoring) after changing from full closed loop to semi closed loop. Through the above steps, the fault of the CNC gantry boring and milling machine was quickly solved. Although the accuracy of the x-axis of the machine tool decreased, the basic function of the machine tool was normal, and the accuracy of the machine tool fully met the production requirements after repair. The x-axis of the machine tool has been used for 1 year since it was changed into a semi closed loop. The machine tool is in normal use, and the processed products have no quality problems

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