What are the causes and solutions of CNC machining accuracy
- The workpiece size is accurate and the surface brightness is poor
Obstacles: the tool tip is damaged and not sharp; the machine tool resonates and is instable; the machine tool crawls; and the processing technology is not good.
Treatment plan: if the tool is not sharp after being worn or damaged, it is necessary to grind the tool from the beginning or select a better tool to set it from the beginning; if the machine tool resonates or is instable, adjust the level and lay the basic, unchanged and stable; Due to the creeping of the machine, due to the wear of the carriage guide rail and the wear or looseness of the lead screw ball, the machine tool should pay attention to the maintenance, clean the iron wire after going to work, and quickly add smooth oil to reduce the conflict; select the appropriate cooling liquid for workpiece processing, even if it can meet the processing requirements of other processes, select a higher spindle speed.
- The taper of workpiece is large and small
Obstacles: the level of the machine tool is not adjusted well, one high and one low, resulting in instable placement; when turning the long shaft, the raw material of merit is hard, and the cutting tool is deep, forming the phenomenon of giving way to the cutter; the difference between the tailstock thimble and the spindle.
Treatment plan: adjust the levelness of the machine tool with a level gauge, lay a solid foundation, keep the machine tool unchanged and increase its toughness; select the correct process and appropriate cutting feed rate to prevent the tool from being forced to yield to the cutter; adjust the tailstock.
- The driver phase light is normal, but the size of the workpiece processed is large or small
Obstacles: long term high-speed operation of the machine tool carriage results in the wear of the screw rod and bearing; the repeated positioning accuracy of the tool carrier has errors in long-term use; the carriage can accurately return to the starting point of processing each time, but the processing workpiece size still changes. This phenomenon is usually formed by the spindle, the high-speed rotation of the spindle makes the bearing wear very important, forming the processing size change.
Processing plan: use the dial indicator to lean against the bottom of the tool rest, and compile a constant cycle program through the system to check the repeated positioning accuracy of the carriage, adjust the screw rod clearance, and replace the bearing; use the dial indicator to check the repeated positioning accuracy of the tool rest, adjust the machinery or replace the tool carrier; Use the dial indicator to check whether the workpiece is returned to the starting point of the program accurately. If it is possible, check the spindle and replace the bearing.
- The difference between the size of the workpiece and the essential size is several millimeters, or there is a great change in a certain axial direction
Obstacles: the speed of rapid positioning is too fast, and the drive and motor can not respond; after long-term conflict and consumption, the mechanical drag screw rod and bearing are too tight and stuck; the tool carrier is too loose and can not be locked tightly; the compiled program error, the head and tail are not taken care of or the cutter compensation is not canceled; the electronic gear ratio or step angle configuration of the system is wrong.
Treatment plan: if the positioning speed is too fast, the go speed should be adjusted appropriately, and the driver and motor can work normally under the rated operating frequency by cutting with slowing down and time; if the drag plate and screw rod crane bearing are too tight and stuck after the machine tool is worn, it must be adjusted from the beginning; If the tool holder is too loose after tool change, it is necessary to check whether the tool holder reversing time is satisfied, whether the worm gear inside the tool holder is worn, whether the clearance is too large, whether the installation is too loose, etc.; if it is caused by the program, it is necessary to correct the program, comply with the requirements of the workpiece drawing, select the correct processing technology, and write the accurate program according to the instructions in the footnotes; If it is found that the size error is too large, the test system parameters are correctly configured, the unique is whether the parameters such as electronic gear and step angle are damaged, which can be measured by dial indicator.
- The effect of arc processing is not dream, and the size is not in place
Obstacle causes: resonance caused by repeated vibration frequency; processing technology; parameter configuration bifurcation, too large feed speed, resulting in out of step in arc machining; loose or tight lead screw caused by large gap; wear of synchronous belt.
Treatment plan: find out the parts with resonance, change its frequency and prevent resonance; study the processing technology of workpiece raw materials and correctly program; as for stepping motor, the processing speed f cannot be too large; whether the machine tool is installed stably and stably, whether the carriage is too tight after wearing, the gap is increased or the tool holder is loose; replace the synchronous belt.
The above is the cause of poor CNC machining accuracy and solutions, hope to help you
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