How to deal with poor machining accuracy of vertical machining center?

The largest processing attribute of vertical machining center is that the consistency of the size of the batch workpiece is very high, we know that the traditional processing of the original workpiece from one process to another process, have to go through a clamping process, this process is difficult to achieve the processing size of each part is completely consistent by manual operation, of course, this does not mean that the workpiece is out of whack. As long as the tolerance band of the workpiece is qualified, it appears that some workpiece size may be on the large difference, some workpiece in the middle difference, and some workpiece may be on the differential, and it is difficult to maintain the dimensional consistency of the workpiece.

Therefore, the utilization rate of vertical machining center at this stage is the highest in small and medium-sized processing enterprises, of course, vertical machining center is also the most cost-effective machine tool in CNC machine tools, he has high processing efficiency and high processing accuracy, and from these two aspects, it also solves the problem of maintaining the size consistency of the workpiece. Of course, if the numerical control parameters are set improperly or the operation is improper, the vertical machining center will also appear from time to time in the actual machining. This article briefly introduces the common causes and solutions of vertical machining centers:

The machining accuracy of the vertical machining center is mainly manifested as: high surface roughness value of the inner hole machining, the inner hole is not round, the position accuracy of the reamed hole is abnormal, the inner surface of the hole has obvious edge, the center line of the hole after the reaming is not straight, the aperture increases, the aperture decreases, etc.

First, the precision of the hinged hole position is out of line

Cause: It may be caused by the wear of the guide sleeve of the vertical machining center, the bottom end of the guide sleeve is too far from the workpiece, the length of the guide sleeve is short, the accuracy is poor, and the main shaft bearing is loose.

Solution: When reaming the vertical machining center, if the position accuracy of the hole is too poor, the following maintenance can be done according to the above easy problems, regularly replace the guide sleeve, lengthen the guide sleeve, improve the accuracy of the guide sleeve and the reamer clearance, maintain the machine tool in time, and adjust the spindle bearing clearance.

Second, the surface roughness of the inner hole is high

Cause: Vertical machining center machining inner hole surface roughness is high, there are many reasons, It may be due to the cutting speed is too high, the cutting fluid selection is not suitable, the main deflection Angle of the reamer is too large, the reamer margin is too large, the reamer margin is not uniform or too small, the cutting edge is not sharp, the reamer cutting edge is too wide, the chip removal is not smooth when reaming, the reamer is excessive wear, and the milling tool and the part material are not matched.

Solution: Because there are many reasons for high machining roughness, it is more complicated to solve, and it can be started from the following aspects: Reduce the cutting speed, select the cutting fluid according to the processing material, appropriately reduce the reaming allowance, improve the position accuracy and quality of the bottom hole before the reaming or increase the reaming allowance, increase the chip-holding slot space or use the reamer with the edge Angle, so that the chip removal is smooth, regularly replace the reamer, reasonable selection of tools, such as the tool suitable for steel processing.

Third, the processing aperture increases

Causes: The reasons for the gradual increase in the aperture of the vertical machining center may be: The design value of the outer diameter of the reamer is too large or the edge of the reamer has burrs, the cutting speed is too high, the feed amount is improper or the processing allowance is too large, the main deflection Angle of the reamer is too large, the bending of the reamer, the chip accumulation on the edge of the reamer, the swing difference of the reamer edge is too bad when grinding, the cutting fluid is not suitable, and it may be the problem of the CNC machine tool itself. These problems may also occur when the main shaft is bent or the main shaft bearing is too loose or damaged.

Solution: The following measures can be taken according to the actual inspection: According to the specific situation, appropriately reduce the outside diameter of the reamer, reduce the cutting speed, properly adjust the feed or reduce the processing allowance, appropriately reduce the main deflection Angle, straightening or scrapping the bent reamer, choose the cutting fluid with better cooling performance, adjust or replace the spindle bearing, want to learn UG programming CNC programming can be added

Or replace the entire spindle.

Fourth, the hinged inner hole is not round

Cause: The processing of the inner hole is not round, roundness is not enough mainly due to the following factors: the reamer is too long, insufficient rigidity, vibration during reaming, the main deflection Angle of the reamer is too small, the reaming margin is too small, the inner hole surface has notches, cross holes, especially the hole surface has sand holes, pores, and may be the machine tool spindle bearing loose.

Solution: It can be started from the following aspects: the installation of the reamer should adopt rigid connection, select qualified reamer, control the hole position tolerance of the pre-machining process, use the reamer with different pitch, select qualified blank, adjust the spindle clearance of the machine tool in time, etc.

5. The center line of the reaming hole is not straight

Causes: vertical machining center machining holes appear, the center line is not straight possible reasons may be: When drilling the hole inclination, especially when the aperture is small, due to the poor rigidity of the reamer, the original bending degree can not be corrected, the main deflection Angle of the reamer is too large, and the guidance is poor, so that the reamer is easy to deviate from the direction in the reamer, the cutting part of the taper is too large, and the reamer discontinuity is displaced at the gap in the middle of the hole.

Solution: increase the reaming or boring process correction hole, reduce the main deflection Angle, adjust the appropriate reamer, replace the reamer with the guide part or lengthen the cutting part, pay attention to the correct operation.