xiehe model

1. The workpiece has precise dimensions and poor surface finish

The cause of the failure: the tip of the tool is damaged and not sharp; the machine tool of the cncl machining center has resonance, and the placement is not stable; the machine tool has creeping phenomenon; the processing technology is not good.

Solution: If the tool is not sharp after being worn or damaged, resharpen the tool or choose a better tool to re-set the tool; if the machine tool resonates or is placed unstable, adjust the level, lay a foundation, and fix it stably; the reason for the machine crawling is dragging The guide rail of the plate is severely worn, and the balls of the screw are worn or loose. The machine tool should be maintained carefully. The iron wire should be cleaned after work, and lubricating oil should be added in time to reduce friction; Under certain circumstances, try to choose a higher spindle speed.

2. The workpiece has a taper and a small head phenomenon

The cause of the failure: the level of the machine tool is not adjusted properly, one is high and the other is low, resulting in unstable placement; when turning the long axis, the contribution material is relatively hard, and the tool engages the knife deeply, resulting in the phenomenon of tool giving; the thimble of the tailstock is not concentric with the main shaft.

Solution: Use a spirit level to adjust the levelness of the machine tool, lay a solid foundation, fix the machine tool to improve its durability; choose a reasonable process and appropriate cutting feed to prevent the tool from giving way under force; adjust the tailstock.

3. The phase light of the driver is normal, but the scale of the processed workpiece varies from large to small

The cause of the failure: the drag plate of the cncl machining center machine tool runs at high speed for a long time, resulting in the wear of the screw and bearing; the repeated positioning accuracy of the tool holder produces errors during long-term use; the drag plate can accurately return to the starting point of processing every time, but the workpiece The scale still changes. This phenomenon is generally caused by the main shaft. The high-speed rotation of the main shaft causes serious wear of the bearing, resulting in changes in the processing scale.

Solution: use the dial indicator to lean against the bottom of the tool holder, and modify a fixed cycle program through the system at the same time, check the repeated positioning accuracy of the carriage, adjust the gap of the screw, and 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 gauge to check whether the workpiece is accurately returned to the starting point of the program after processing the workpiece. If it is possible, repair the spindle and replace the bearing.

4. The size of the workpiece is a few millimeters different from the actual size, or there is a big change in a certain axis

The cause of the fault: the fast positioning speed is too fast, the drive and the motor cannot respond; after a long period of friction and wear, the mechanical carriage screw and bearing are too tight and stuck; the tool post is too loose after tool change, and the lock is not tight; The program is wrong, there is no response from the head and tail, or the tool compensation is not cancelled; the system's electronic gear ratio or step angle setting is wrong.

Solution: If the fast positioning speed is too fast, properly adjust the GO speed, cutting acceleration and deceleration speed and time to make the drive and motor work normally at the extra operating frequency; after the wear and tear of the machine tool, the bearings of the carriage and the screw crane are too tight If it is stuck, it is necessary to adjust and correct it from the beginning; if the tool holder is too loose after changing the tool, check whether the rotation time of the tool holder is satisfactory, check whether the worm gear inside the tool holder is worn, whether the gap is too large, whether the device is too loose, etc.; if it is a program If the cause is formed, it is necessary to modify the program, improve according to the requirements of the workpiece drawing, select a reasonable processing technology, and write the correct program according to the instruction requirements of the manual; if the scale error is found to be too large, check whether the system parameters are set reasonably, especially the electronic gear Whether parameters such as step angle and step angle are damaged, this phenomenon can be measured by dial indicator.

5. The machining arc effect of cncl machining center is not ideal, and the scale is not in place

Cause of failure: resonance caused by the stacking of oscillation frequency; processing technology; unreasonable parameter setting, excessive feed speed, which makes arc processing out of step; looseness caused by large screw gap or out of step caused by over tight screw; synchronous belt wear and tear.

Solution: Find out the parts that resonate, change their frequency, and avoid resonance; consider the processing technology of the workpiece material, and program reasonably; for stepper motors, the processing speed F cannot be set too large; whether the machine tool is installed firmly, placed smoothly, dragged Whether the plate is too tight after wear, the gap increases or the tool holder is loose, etc.; replace the timing belt.

6. In mass production, the workpiece is occasionally out of tolerance

Cause of failure: It is necessary to carefully check the tooling fixtures, and take into account the operator's operation method and the reliability of the clamping. Because of the size change caused by the clamping, it is necessary to improve the tooling so that the workers can avoid human negligence and make misjudgments as much as possible; CNC The system may be fluctuated by the external power supply or automatically generate interference pulses after being disturbed, which are transmitted to the driver and cause the driver to accept the remaining pulses to drive the motor to take away or run less.

Solution: Understand and grasp its rules, try to use some anti-interference measures, such as: strong electric field interference strong electric cable and signal line of weak electric signal isolation, add anti-interference absorbing capacitance and use shielding wire isolation, in addition, check the ground Whether the cable is connected firmly, the grounding contact is closest, and all anti-jamming measures are taken to prevent the system from being disturbed.

7. There is a change in the processing of a certain process of the workpiece, and the scale of other processes is accurate

Cause of failure: Whether the parameters of the program in this block are reasonable, whether it is within the predetermined track, and whether the programming format meets the requirements of the manual.

Solution: When there are disordered teeth and wrong pitch in the thread program segment, immediately think of the peripheral equipment (encoder) for thread processing and the objective factors of this function.

8. Each process of the workpiece has a phenomenon of increasing or decreasing

Causes of failure: wrong programming; unreasonable system parameter setting; improper equipment setting; mechanical transmission parts have regular and periodic change failures.

Solution: Check whether the instructions used by the program are executed according to the requirements of the instructions. You can judge by playing the dial indicator. Position the dial indicator at the starting point of the program so that the carriage returns to the starting position after the program is completed, and then repeat the execution Just observe the results and grasp the rules; check whether the system parameters are set reasonably or are considered to be changed; whether the single calculation of the relevant machine tool equipment meets the requirements on the connection calculation coupling parameters, and whether the pulse equivalent is accurate; check whether the transmission part of the machine tool is damaged, the gear Whether the coupling is uniform, check whether there are periodic and regular faults, and if so, check the key parts and eliminate them.

9. The scale change caused by the system is unstable

Cause of failure: unreasonable system parameter setting; unstable working voltage; system out of step due to external interference; capacitor has been added, but the impedance between the system and the driver does not match, resulting in the loss of useful signals; the signal between the system and the driver Abnormal transmission; system damage or internal failure.

Solution: Whether the speed and acceleration time are too large, whether the spindle speed and cutting speed are reasonable, whether the operator's parameter modification causes the system function to change; install a voltage stabilizing device; make sure that the grounding wire has been firmly connected, and the pulse output contact of the driver Add an anti-jamming absorption capacitor; select the appropriate capacitor type; check whether the signal connection line between the system and the driver is shielded, whether the connection is reliable, check whether the pulse signal of the system is lost or added; send it to the factory for repair or replace the motherboard.