What's wrong with CNC machining accuracy?
1. Workpiece size is accurate, surface finish is poor fault reasons: tool tip damage, not sharp; machine tool resonance, placement is not stable; machine tool crawling phenomenon; poor processing technology.
Solution: If the tool is not sharp after wear or damage, grind the tool again or choose a better tool to re-align the tool; if the machine tool is resonant or placed unsteadily, adjust the level, lay the foundation and fix the tool smoothly; the reason of mechanical crawling is that the trawler guide rail is worn badly, the ball screw is worn or loosened, the machine tool should be maintained carefully, and the wire should be cleaned after going to and going to work, and timely moistened. Lubricating oil to reduce friction; select suitable cooling fluid for workpiece processing, in order to meet the processing requirements of other processes, try to choose a higher spindle speed.
2. Workpiece taper size head failure causes: machine tool placement level is not adjusted well, one high one low, resulting in placement instability; turning long axis, the contribution material is relatively hard, the cutter knife deep, resulting in knife-letting phenomenon; tailstock pin and spindle are not centralized.
Solution: Use level instrument to adjust the level of machine tool, lay a solid foundation, fix the machine tool well and improve its toughness; choose reasonable technology and appropriate cutting feed to avoid tool force concession; adjust tailstock.
3. The driver phase lamp is normal, but the small fault causes when the workpiece size is large: the machine tool trawler runs at a high speed for a long time, which results in the wear of the screw and bearing; the repetitive positioning accuracy of the tool holder produces deviation in the long-term use; the trawler can accurately return to the processing starting point every time, but the size of the workpiece is still changing. This phenomenon is generally caused by the spindle. The high speed rotation of the spindle causes serious wear of the bearing, which leads to the change of processing size.
Solution: Depend on the bottom of the tool holder with the dial indicator, and edit a fixed cycle program through the system to check the repetitive positioning accuracy of the trailer, adjust the clearance of the screw and replace the bearing; check the repetitive positioning accuracy of the tool holder with dial indicator, adjust the machine or replace the tool holder; check whether the workpiece is accurately returned to the starting point of the program after processing with dial indicator, and if possible, repair the spindle. Change bearings.
4. The size of the workpiece differs from the actual size by several millimeters, or there is a great change in the axis of the workpiece. The reason for the failure is that the speed of rapid positioning is too fast to respond to the drive and motor; the drag plate screw and bearing of the machine are too tightly jammed after a long period of friction loss; the tool holder is too loose and the lock is not tightened after tool change; the editing procedure is wrong, and the system ends without the head and tail responding or canceling the tool repair; Error setting of electronic gear ratio or step angle.
Solution: If the speed of quick positioning is too fast, the GO speed will be adjusted appropriately, and the speed of cutting acceleration and deceleration and time will make the driver and motor work normally at the rated operating frequency; if the tractor and screw crane bearings become too tight after machine tool wear, they must be readjusted and repaired; if the tool holder is too loose after tool change, the reverse time of the tool holder will be checked and the vortices inside the tool holder will be checked. Whether the gear and worm are worn, whether the clearance is too large, whether the installation is too loose, etc. If it is caused by the program reasons, the program must be modified, according to the requirements of workpiece drawings, improve, select reasonable processing technology, write the correct program according to the instructions of the manual; if the size deviation is too large, check whether the parameters of the system are set reasonably, especially the electronic gear and the step angle, etc. Whether the parameters are destroyed or not can be measured by a dial indicator.
