Analysis and Treatment of Failure of Automatic Tool Cutting

Analysis and processing of automatic lathe machining tool failure At present, the automatic tool changer (ATC) of the machining center has two common types of tool change methods. One is that the tool is directly exchanged by the spindle from the tool magazine, and the second is to rely on the robot to complete the spindle. Tool exchanges on the magazine. This type of tool change is suitable for small machining centers. The tool magazine is small, the number of tools is small, and the tool change is simple. When a tool failure or the like occurs, it can be easily found and can be eliminated in time. The second type of tool change is a more complex one in terms of structure and action. This article takes the Vcenter-80 machining center as an example to analyze the failure phenomenon and handle it.

1. Analysis of tool change operations in the machining center From the perspective of the PLC drawing, the tool change program of this machine tool has reached more than 900 steps, and it is difficult to read its working principle. Here, the ATC data exchange, transfer, storage, and tool number storage are briefly transferred, and the tool change operations are briefly described as follows: CNC tool change command (M06) → tool set down → descent into position → robot rotation → rotation deceleration → rotation In place (X4.7) → Spindle tool release → Release in place → Robot rotation → Rotation deceleration → Rotation in place → Spindle tool clamping → Clamping in place (X2.5) → Robot reversal → Mechanical in-place, tool change completed. Among them, the fast and slow speed of the manipulator is realized by the frequency converter, and when the motor rotates, the mechanical cam drive is driven to realize the rise and fall of the manipulator.

2, the failure of the knife out of the knife failure phenomenon appears longer time, the beginning, occasionally once, once a month, or even two or three months, that is caused by accidental factors, did not attract sufficient attention, slowly appear once a week , Even twice, accompanied by a situation where the knife on the spindle is not in place. Later, it slowly evolved into a failure in a shift many times, which seriously affected the production schedule and caused the production of waste products. Careful observation, there are two cases of failure of the knife, one is the knife after the completion of the processing step, one is that this step did not process, the tool fell on the table. In the machining process, the tool changing operation is performed and the operation sequence is normal. Therefore, there is no alarm phenomenon when the knife is missing or the knife is loaded (into the spindle). Only the operator checks or hears the abnormal sound of the knife in the workpiece. In the event of a failure, failure will occur. As a result, batch waste will sometimes occur due to a blade failure in an automated processing line.

3, failure analysis and processing (1) check the robot to perform ATC tool replacement troubleshooting steps, the robot stop at the vertical limit position. Check the two claws on the arm of the manipulator and the attachment springs that support the claws. No problems were found, indicating that the manipulator gripped the tool tightly, and the knife disappeared when the manipulator turned.

(2) Checking the tool holding situation According to the analysis of the phenomenon that the tool has not been installed on the spindle, it may be that the disc spring cannot hold the tool tightly in the hole in the spindle, so that the tool is not installed in place, or even the tool is not loaded and the knife disappears. . The interior of the spindle was disassembled and several disc springs were found to have broken. Then replaced all disc springs. There was no problem with the test run. After a shift, the knife disappears.

(3) check the tool change program for this failure only occurs in the tool change action, regardless of other actions, edit an automatic tool change and repeat the program, and run this program, in order to find out the real reason for the knife. The automatic tool change program is as follows: O0200→S500→M03→G04X3.0→M06→M99→%

During program operation, the following conditions were found: The spindle tool was not clamped, and even if there was no clamping action, the robot turned, and the tool broke. According to the sequence of tool change operations in the previous text, the tool failure due to misoperation of the spindle tool clamped positional switch is analyzed. Open the ladder diagram of the PLC, monitor the limit switch (input is X2.5), and repeatedly press the stroke switch, and find that twice of the 20 times of press-fitting, there are 3 times of X2.5 being “0” and the phenomenon appears twice. The phenomenon that the rear X2.5 cannot be changed from the "1" state to the "0 state" occurs twice. According to the above, it is determined that the travel switch is broken. This switch is OMRONZC-Q2255, replaced with domestic CXW5-11Q1, the test is normal. A week later, the operator still reflected the knife-off phenomenon, of course, the frequency of occurrence is small, which shows that the failure of the knife has not been ruled out.

(4) Troubleshooting Two hours of repeated operation, automatic tool change several hundred times. Finally found a failure: In the case of the robot is not in place, the tool on the spindle is released, the robot does not grasp the knife, and the knife off phenomenon occurs, indicating that the robot in place magnetic induction switch malfunction. Replace the switch E2E-CR8C1. The fault still exists. Check the PLC ladder diagram. The switch input point is X4.7. X4.7 is a normally open point in the ladder diagram. When this switch senses, the state is “0” and when it is not sensed, the state is “1”. Its logic state is opposite to the common sense switch logic state. When X4.7 is disconnected, it will cause X4.7 to be in "1" state. Therefore, the line of X4.7 is checked and it is found that X4.7 at the terminal block behind the electromagnetic induction switch is loose, whenever the automatic tool change occurs, The slight vibration caused by a series of actions of the manipulator cam causes the X4.7 line to be disconnected. When the manipulator is not in place, the sensor switch of the release tool is still inducted, but because of the disconnection, X4.7 is " In the 1" state, when the machine is not in place, the tool is released and a tool failure occurs. In this case, the tool failure is the tool that has been processed by the tool, and the tool mentioned above is the failure of the tool without any machining step.

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