Troubleshooting methods for common problems in operation of slant bed cnc lathe

2020-09-29

Slant bed CNC lathe is a typical mechatronics product that comprehensively uses advanced technologies such as computer technology, automatic control technology, and superb measurement technology. Its control system is complex and expensive. Once a failure occurs, many people will stay away from it because of its "expensive value", and they will often hire professional maintenance personnel. It wastes manpower, material resources and financial resources, and also delays working hours. In fact, for some common operation problems, as long as the operator is diligent in thinking, good at summarizing, and focusing on accumulation, it is not difficult to find and solve the problems.

1. In manual mode, the coordinate axis does not move
Phenomenon: During manual operation, the machine coordinate axis does not move, the coordinate value does not change, the M, S, and T functions are executed normally, and the system has no alarm display.


Analysis and solution: In this case, the system did not generate an alarm when the failure occurred, and the M, S, and T functions were executed normally. Based on this, it can be preliminarily judged that the CNC system, servo drive, etc. should have no fault. Therefore, it can be analyzed from the manual conditions, carefully check the input of the manual direction keys, the selection of the manual direction, etc. are all normal, and then carefully observe the "Current Position" page of the operation panel, and find that the manual rate, actual rate, and feed rate are all zero . Confirm that the coordinate axis does not produce manual operation because the manual movement speed is zero. Re-adjust the feed rate percentage and manual operation will return to normal.


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2. the automatic operation is not in place

Phenomenon: If you want to position the tool tip of No. 1 tool to a known point on the workpiece, after correctly inputting the relevant commands in the program input mode (MDI), the M and S commands will be executed normally, the machine coordinate axis will move, and the CRT screen will display correctly Position, but the tool tip does not move to the predetermined position, the system has no alarm display.


Analysis and solution: Because the machine tool returns to the set point in a normal process, it does not reach the set position. Such failures are usually related to tool compensation execution. Checking the execution of tool compensation, it is found that the tool function is T0103, and the tool No. 1 executes the tool compensation value of No. 3 tool, which causes the tool tip to not move to the predetermined position. Re-enter T0101 in the input mode (MDI) to solve this fault.

3. Irregular pitch in thread processing
Phenomenon: When the slant bed cnc lathe is processing the thread, the pitch of the initial section of the thread is irregular, that is, the so-called messy teeth appear.


Analysis and solution: When thread processing is performed on a CNC lathe, the interpolation is performed between the X-axis rotation angle and the Z-axis feed. The chaotic tooth is caused by the inability to synchronize the feeds of the X-axis and Z-axis, and the lag characteristics of the machine tool servo system. GSK980T is an economical CNC system. The spindle speed is open-loop controlled. Under different loads, the spindle start time is different, and the spindle speed is unstable at the beginning, and the speed will change accordingly. The thread cutting starts from detecting the position on the spindle. The encoder starts after one revolution of the signal, which may cause the X-axis and Z-axis feeds to fail to achieve synchronization. The above problems can be solved by modifying the program:
· Change the positioning point of the thread processing program to make it far away from the workpiece. In this way, the unstable change of the spindle speed is completed in the space. After stability, the tool really touches the workpiece and then starts thread processing.
· Add G04 pause command before spindle rotation command M03 and thread processing command to ensure that the spindle speed is stable before starting thread processing.

4. The processing program cannot be executed
Phenomenon: After the CNC lathe is turned on, select the name of the machining program, and press the autorun key, the M, S, and T functions are executed according to the program command, and the coordinate value changes are displayed without exception, but the almost-crossing coordinate axis does not move, as specified by the program The action is not executed.


Analysis and solution: In the event of such a fault, the first thing that comes to mind is to check whether the feed speed and feed green are zero, and the result is normal. Further inspection found that the indicator light of the machine interlock button on the operation panel was on. After the interlock was turned off, the program was executed normally.

5. halfway to the knife
Phenomenon: In the process of CNC turning, a non-reference tool collapses or the tool tip wears and affects the machining accuracy. (This example assumes that the No. 3 non-reference tool has collapsed)


Analysis and solution: This type of failure often occurs when unskilled workers operate CNC lathes. After the fault occurs, we should immediately press the "Pause", "Reset", "Program zero", "Run" and other keys on the operation panel to cancel the No. 3 tool compensation, and reload the appropriate tool at the No. 3 tool position. , Turn on the power, measure the diameter α of a certain part of the workpiece, start the spindle, lightly touch the surface with the tip of the No. 3 tool, press the "tool offset" key on the operation panel, and enter X "α" at the tool offset number 103 ; Exit the tool, stop the spindle, measure the distance β from a step of the workpiece to the origin of the workpiece, start the spindle, lightly touch the step with the tip of the No. 3 tool, press the "tool offset" key on the operation panel, and set the tool offset number Enter Z "β" at 103. The system automatically calculates the compensation of No. 3 tool after reinstallation.

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