Causes of unstable workpiece processing on Dalian high speed CNC vertical lathe

1. The workpiece has accurate dimensions and poor surface finish

Fault cause: the tool tip is damaged and not sharp; The machine tool resonates and is placed unsteadily; Creeping phenomenon of machine tool; The processing technology is not good.

Solution: if the tool is not sharp after being worn or damaged, regrind the tool or select a better tool to set the tool again; In case of resonance or unstable placement of the machine tool, adjust the level, lay the foundation and fix it stably; The reasons for the creeping of the machine are the fierce wear of the carriage guide rail and the wear or looseness of the lead screw ball. The machine tool should be maintained carefully. After going to and from work, the iron wire should be cleaned and lubricating oil should be added in time to reduce the conflict; Select the appropriate coolant for workpiece processing, and try to select a higher spindle speed when it can meet the processing requirements of other processes.

2. Large and small taper head of workpiece

Fault reason: the placement level of the machine tool is not adjusted well, one high and one low, resulting in unstable placement; When turning a long shaft, the dedication data is relatively hard and the cutting tool is deep, resulting in the phenomenon of giving way to the cutting tool; The ejector pin of tailstock is not concentric with the main shaft.

Solution: use the level to adjust the levelness of the machine tool, lay a thick foundation, fix the machine tool and improve its patience; Select a reasonable process and appropriate cutting feed to prevent the tool from being forced to yield; Adjust the tailstock.

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

Fault cause: the machine tool carriage runs at high speed for a long time, resulting in the wear of screw rod and bearing; The repeated positioning accuracy of the tool holder has errors in long-time application; The workpiece can be processed back to the starting point accurately every time. This phenomenon is generally caused by the spindle. The high-speed rolling of the spindle makes the bearing wear severe, resulting in the change of machining scale. Metal processing wechat has good content and deserves attention.

Solution: use the dial indicator to lean against the bottom of the tool holder, revise a fixed cycle program through the system together, check the repeated positioning accuracy of the carriage, adjust the screw clearance and replace the bearing; Check the repeated positioning accuracy of the tool rest with a dial indicator, adjust the machinery or replace the tool rest; Use a dial indicator to check whether the processed workpiece accurately returns to the starting point of the program. If it can, overhaul the spindle and replace the bearing.

4. The dimension of the workpiece differs from the actual dimension by a few millimeters, or there is a great change in one axis

Fault reason: the speed of fast positioning is too fast, and the drive and motor can't respond; After long-time conflict and loss, the mechanical carriage screw rod and bearing are too tight and stuck; The tool holder is too loose after changing the tool and cannot be locked tightly; The corrected procedural fault, the head and tail are not taken care of or the knife repair is completed without canceling; The electronic gear ratio or step angle setting of the system is wrong.

Solution: if the fast positioning speed is too fast, properly adjust the speed of go, cutting acceleration and deceleration and time to make the driver and motor operate normally under additional operating frequency; If the carriage and screw crane bearings are too tight and stuck after the machine tool is worn, it is necessary to readjust and correct them; If the tool holder is too loose after changing the tool, check whether the reversing time of the tool holder is satisfactory, whether the worm and worm inside the tool holder are 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 modify 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. If this phenomenon appears, it can be measured by playing a dial indicator.

5. The effect of processing circular arc is not ideal and the scale is not in place

Fault cause: resonance caused by overlapping vibration frequency; Processing technology; The parameter setting is unreasonable and the feed speed is too large, which makes the arc machining out of step; Looseness caused by large screw clearance or out of step caused by too tight screw; The timing belt is worn.

Solution: find out the resonance parts and change their frequency to prevent resonance; Considering the processing technology of workpiece data, reasonably compile the program; For the stepper motor, the processing speed f cannot be set too large; Whether the device of the machine tool is firm and placed stably, whether the carriage is too tight after wear, the gap increases or the tool holder is loose; Replace the timing belt. Metal processing wechat has good content and deserves attention.

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

Cause of fault: it is necessary to carefully check the tooling and fixture, and consider the operator's operation method and the reliability of the fixture. Due to the scale change caused by the fixture, it is necessary to improve the tooling to prevent the workers from making false judgment due to human negligence; The numerical control system may be disturbed by the fluctuation of external power supply or the disturbance pulse, which is transmitted to the drive, causing the drive to accept the remaining pulse and drive the motor to take away or leave less,

Solution: understand and grasp the rules, and try to choose some anti-interference methods, such as blocking the strong current cable disturbed by the strong electric field from the signal line of the weak current signal, participating in the anti-interference absorption capacitance and selecting the shielding line. In addition, check whether the ground wire is firmly connected and the grounding contact Z is close. Adopt all anti-interference methods to prevent the system from being disturbed.

7. The processing of one process of the workpiece is changed, and the dimensions of other processes are accurate

Fault reason: whether the program parameters of this program section are reasonable, whether they are in the reserved track, and whether the programming pattern meets the requirements of the manual

Solution: when the thread program section presents disordered teeth and wrong pitch, it is immediately associated with the peripheral equipment (encoder) for processing threads and the objective factors of this function.

8. Each working procedure of the workpiece has the phenomenon of increasing or decreasing step by step

Fault cause: programming fault; Unreasonable setting of system parameters; Improper equipment setting; Mechanical transmission parts have regular periodic changes

Solution: check whether the instructions used in the program are performed according to the requirements specified in the manual. It can be judged by playing the dial indicator. Locate the dial indicator at the starting point of the program, let the carriage return to the starting point after the program is completed, and then repeat the performance, even if the results are investigated and the rules are grasped; Check whether the system parameters are set reasonably or considered to be changed; Whether the coupling parameters of relevant machine tools and equipment meet 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, and whether there are periodic and regular defects. If so, check the key part and clean it.

9. The scale change caused by the system is unstable

Fault cause: unreasonable system parameter setting; Unstable operating voltage; 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; Abnormal signal transmission between system and driver; System damage or internal defects.

Solution: whether the acceleration time is too large, whether the spindle speed and cutting speed are reasonable, and whether the operator's parameter correction leads to the change of system function; Install voltage stabilizing equipment; The grounding wire is determined to be firmly connected, and an anti disturbance absorption capacitor is added at the pulse output contact of the driver; Select the appropriate capacitor model; Check whether the signal wiring between the system and the driver is shielded, whether the connection is firm, and whether the system pulse generation signal is lost or added; Send to the factory to repair or replace the motherboard.