CNC machine tools in the processing of the workpiece, there will always be problems, sometimes unstable, today together to analyze the causes of instability in the processing process and solutions, hope to help you!

1, the workpiece size is accurate, the surface finish is poor

Cause of the problem: the tip of the tool is damaged, not sharp; The machine tool resonates and is not placed smoothly; The machine tool has creeping phenomenon; The processing technology is not good.

Solution: the tool is not sharp after wear or damage, then re-sharpen the knife or choose a better tool to re-set the knife; The machine tool resonance or placement is not stable, adjust the level, lay the foundation, fixed and stable; The reason for the mechanical creep is the fierce wear of the drag guide rail, the lead screw ball wear or loose, the machine tool should pay attention to maintenance, the wire should be cleaned after work, and the lubricating oil should be added in time to reduce the conflict; Select the appropriate workpiece processing coolant, in the case of reaching the processing requirements of other processes, as far as possible to choose a higher spindle speed.

2, the workpiece taper size head phenomenon

The reason for the fault: the level of the machine tool placement is not adjusted well, one high and one low, and the placement is not stable; When turning a long shaft, the dedication data is relatively hard, the cutting tool is relatively deep, forming the phenomenon of letting the knife; Tail seat thimble and spindle different center.

Solution: Use the level to adjust the levelness of the machine tool, lay a solid foundation, fix the machine tool to improve its tolerance; Select reasonable technology and appropriate cutting feed to prevent the cutting tool force; Adjust the tailstock.

3, the driver phase light is normal, and the size of the workpiece processed is large and small

The cause of the fault: the long time high-speed operation of the machine tool drag plate, resulting in screw and bearing wear; The repeated positioning accuracy of the tool holder has errors during long time operation. The drag plate can be accurately returned to the starting point each time, but the workpiece size is still changed. This phenomenon is generally caused by the spindle, the high-speed rolling of the spindle makes the bearing wear severe, resulting in changes in the processing scale. Metal processing wechat, the content is good, worthy of attention.

Solution: With the dial indicator at the bottom of the tool holder, together with the system correction of a fixed cycle program, check the repeated positioning accuracy of the drag plate, adjust the screw gap, replace the bearing; Use the dial indicator to check the repeated positioning accuracy of the tool holder, adjust the machine or replace the tool holder; Use a dial indicator to check whether the workpiece is accurately returned to the program starting point, if it can, then overhaul the spindle and replace the bearing.

4, the workpiece size and the actual size of a few millimeters, or a great change in the axis

Fault cause: the speed of rapid positioning is too fast, and the drive and motor cannot respond; After a long time of conflict and loss, the mechanical drag screw and bearing are too tight and stuck. The tool holder is too loose after changing the tool, and the lock is not tight; The corrected procedural fault, the head and tail did not take care of or did not cancel the knife repair is completed; The electronic gear ratio or step Angle of the system is set incorrectly.

Solution: Fast positioning speed is too fast, then properly adjust the speed of GO, cutting speed and time to make the drive and motor work normally under the extra operating frequency; After the wear of the machine tool, the drag plate and the lead screw crane bearings are too tight and stuck, it is necessary to readjust and correct; If the tool holder is too loose after changing the tool holder, check whether the reverse moment of the tool holder is satisfied, check whether the turbo worm inside the tool holder is worn, whether the gap is too large, whether the device is too loose, etc.; If it is caused by the program, it is necessary to amend the program, improve it according to the requirements of the workpiece drawing, select a reasonable processing technology, and write the correct program according to the instructions of the manual; If the scale error is found to be too large, check whether the system parameters are set reasonably, especially whether the parameters such as electronic gear and step Angle are damaged, and this phenomenon can be measured by a dial indicator.

5, the processing arc function is not ambitious, the scale is not in place

The cause of the problem: the overlap of vibration frequencies leads to resonance; Processing technology; The parameter setting is not reasonable, the feed speed is too large, so that the arc machining is out of step; Loose screw gap caused by large or screw too tight caused by out of step; Synchronization belt wear.

Solution: Find out the resonant part, change its frequency to prevent resonance; Considering the processing technology of workpiece data, reasonable programming; For the stepper motor, the processing speed F can not be set too large; Whether the machine tool device is strong, stable placement, whether the drag plate is too tight after wear, the gap increases or the tool holder is loose; The synchronization tape is replaced. Metal processing wechat, the content is good, worthy of attention.

6. In mass production, the workpiece is accidentally out of order

The cause of the problem: it is necessary to carefully check the fixture, and take into account the operator's operation method, and the robustness of the clamping, because of the scale change caused by the clamping, it is necessary to improve the tooling so that workers can prevent human negligence to make misjudgments; The numerical control system may be affected by fluctuations in the external power supply or be disturbed after the active disturbance pulse is transmitted to the drive, which causes the drive to accept the remaining pulse drive motor to take away or walk less.

Solution: Understand and grasp its rules, try to choose some anti-interference methods, such as: strong electric field interference of strong cable and weak signal signal line barrier, participate in anti-interference absorption capacitance and selection of shielding line barrier, in addition, check whether the ground wire is connected, grounding contact is recent, adopt all anti-interference methods to prevent the system from being disturbed.

7, a process of the workpiece has been changed, and the other processes are accurate

Fault cause: Whether the parameters of the program segment are reasonable, whether it is in the booked track, and whether the programming pattern meets the requirements of the manual

Solution: When the thread program segment presents chaos, the pitch is not correct, and it is immediately associated with the peripheral equipment (encoder) of the thread processing and the objective factors of the function.

8, each process of the workpiece has the phenomenon of increasing or decreasing

Fault cause: program writing fault; The system parameter setting is not reasonable; Improper equipment setup; Mechanical transmission parts have regular periodic changes

Solution: Check whether the instructions used by the program are performed according to the requirements of the manual, which can be judged by the dial indicator, locate the dial indicator at the starting point of the program, let the drag board return to the starting point after the completion of the program, and then repeat the performance even if the investigation results and grasp its rules; Check whether the system parameters are set reasonably or are considered to be changed; Whether the single calculation of the coupling parameters of the relevant machine tool equipment meets the requirements and whether the pulse equivalent is accurate; Check whether the transmission part of the machine tool is damaged, whether the gear coupling is uniform, to see whether there is a periodic, regular fault phenomenon, if there is a look at its key part and give cleaning.

9. The scale change caused by the system is unstable

Fault cause: system parameter setting is unreasonable; The operating voltage is unstable; The system is disturbed by the outside, resulting in the system out of step; Capacitance has been added, but the impedance between the system and the driver does not match, resulting in the loss of useful signals; Signal transmission between the system and the driver is abnormal; System damage or internal problems.

Solution: Speed, speed up time is too large, spindle speed, cutting speed is reasonable, whether the operator's parameter correction leads to system function changes; Install pressure stabilizing equipment; The grounding wire is determined to be firmly connected, and the anti-disturbance absorption capacitor is added to the driver pulse output contact; Select the appropriate capacitor type; Check whether the signal connection line between the system and the driver is shielded, whether the connection is secure, and whether the pulse signal of the system is lost or added; Send motherboard to factory for repair or replacement.