The quality of the workpiece depends not only on the material of the workpiece, but also on the processing technology. Boring is just like this. The boring processing method has a great influence on the processing quality of the workpiece, especially from the perspective of the movement of the boring machine
The formula has a direct influence on the machining accuracy of the hole.
（1） Overhanging boring
1. Boring bar feed suspension boring
In the boring process, with the feeding of the boring bar, the extension length and deformation of the boring bar will increase. Under the influence of cutting force, the deformation of the boring bar at different processing positions will be different, so the bore diameter will be different.
In addition, with the increase of the overhang of the boring bar, the bending caused by the gravity of the boring bar itself also changes. In the whole boring process, the greater the cutting force, the longer the extension length of the boring bar, the greater the deflection of the boring bar, and the axis of the bored hole will be curved, resulting in the roundness error, cylindricity error of the hole and the coaxiality error of the coaxial hole system. Therefore, the boring bar feed suspension boring method is generally suitable for rough machining with low accuracy requirements.
2. Worktable feed suspension boring
In this boring processing mode, although the tip of the boring tool also has deflection under the action of cutting force and the gravity of the boring bar, the extension length of the boring bar remains unchanged during the whole boring processing process due to the use of workbench feeding, so this deflection is a constant value. Only when the feeding direction of the workbench is an accurate straight line, the axis of the hole is a straight line. All deviations in the feed direction of the table can cause bending and deflection of the axis of the hole. Therefore, the accuracy of the holes bored by the worktable feed suspension boring method depends on the accuracy of the boring machine itself.
Under the condition of good accuracy of the machine tool, the machining accuracy of this machining method is higher than that of the boring bar feed suspension boring method, so it is suitable for precision machining.
（2） Support boring method
1. Table feed support boring
In the boring of the feed support of the worktable, the spindle rotates and the worktable feeds. In this processing mode, the distance between the two support points is relatively long. Because it is the support boring through which the boring bar penetrates, the straightness error of the hole axis is small, the change of the hole size is small, and only a very small fixed value is uniformly reduced, so this machining method is suitable for finishing machining.
2. Boring bar feed support boring
When boring in this way, the extension length of the boring bar is unchanged, and the deflection generated by the cutting force is smaller than the deflection of the worktable feed support boring. It has good vibration resistance and can be processed with a wide edge cutter. However, due to the feeding of the boring bar, the position of the boring tool between the supports is changed. The bending caused by the weight of the boring bar will affect the straightness error of the workpiece hole axis. The deformation of the boring bar caused by the cutting force is smaller than that of the worktable feeding support boring. However, since the bending of the hole axis is not easy to correct, it is better to use the worktable feeding support for boring.
