Analyze the five precision fault causes and solutions of CNC machine tools
1, the processing arc effect is not ideal, the size is not in place
The cause of the fault: the overlap of the vibration frequency leads to resonance; the processing technology; the parameter setting is unreasonable, the feed speed is too large, the arc machining is out of step; the looseness caused by the screw gap is large or the screw is too tight; abrasion.
Solution: Find the parts that generate resonance, change their frequency, avoid resonance; consider the processing technology of the workpiece material, and make the program reasonably; for stepper motor, the processing rate F can't be set too large; whether the machine is installed firmly, placed smoothly, drag Whether the board is too tight after wear, the gap is increased or the tool holder is loose; etc.; replace the timing belt. Metal processing WeChat, the content is good, it is worthy of attention.
2, in the mass production, occasionally the workpiece is out of tolerance
The cause of the failure: the fixture must be carefully checked, and considering the operator's operation method and the reliability of the clamping, due to the dimensional changes caused by the clamping, the tooling must be improved so that the worker can avoid the misjudgment of human negligence as much as possible; the numerical control system may When the external power supply fluctuates or is disturbed, the interference pulse is automatically generated, and the drive is transmitted to the drive to receive the excess pulse drive motor to take away or less.
Solution: Understand the rules, try to use some anti-interference measures, such as: strong electric cable interference strong signal and weak electric signal signal line isolation, add anti-interference absorption capacitor and shielded line isolation, in addition, check the ground Whether the connection is firm, the grounding contact is closest, and all anti-interference measures are taken to avoid system interference.
3. There is a change in the processing of one part of the workpiece, and the dimensions of other processes are accurate.
Fault reason: Whether the parameters of the program block program are reasonable, whether it is within the predetermined track, whether the programming format meets the requirements of the manual
Solution: If there is a chaotic tooth in the thread block, if the pitch is wrong, it immediately associates with the peripheral configuration (encoder) of the machining thread and the objective factor of the function.
4. Each process of the workpiece has an increasing or decreasing phenomenon.
Fault reason: programming error; unreasonable system parameter setting; improper configuration setting; mechanical transmission components have regular periodic changes
Solution: Check whether the instructions used by the program are executed according to the required trajectory specified in the manual. You can judge by dialing the dial indicator. Position the dial indicator at the beginning of the program to let the board return to the starting position after the program ends, and then repeat the execution. Even if you observe the results, master the rules; check whether the system parameters are set properly or are considered to be changed; the relevant machine configuration is calculated on the connection calculation coupling parameters to meet the requirements, whether the pulse equivalent is accurate; check the machine transmission part for damage, gear Whether the coupling is uniform, check for periodicity, regular failure phenomena, and if so, check the key parts and give them exclusion.
5, the dimensional change caused by the system is unstable
Fault reason: The system parameter setting is unreasonable; the working voltage is unstable; the system is subject to external interference, causing the system to lose step; the capacitor is added, but the impedance between the system and the driver does not match, resulting in loss of useful signal; signal between system and driver The transmission is not normal; the system is damaged or internal.
Solution: speed, acceleration time is too large, spindle speed, cutting speed is reasonable, whether the operator's parameter modification causes system performance change; install voltage regulator equipment; ground wire and determine that the connection is reliable, the driver pulse output contact Add anti-interference absorption capacitor; select the appropriate capacitor model; check whether the signal connection between the system and the driver is shielded, whether the connection is reliable, check whether the system pulse signal is lost or increased; send the factory for repair or replace the motherboard.
