1. Long hole boring, represented by the coaxial hole system of box parts, is one of the most important contents in metal cutting processing. Although there are still examples of using boring die, guide bushing, bench milling boring machine rear column to support long boring bar or manual centering workpiece rotation 180 °, but in recent years, on the one hand, due to the large number of CNC milling boring machines and machining centers, the coordinate positioning accuracy of various horizontal milling and boring machines and the rotary indexing accuracy of the worktable have been greatly improved, and the long hole boring is gradually rotated by the efficient workbench 180 °The mass production and application of self-positioning turning boring and other side bed layout of ordinary or CNC planer milling and boring machine, from the machine tool structure, the turnaround boring of the self-positioning of the worktable rotates 180 °, and has almost become the method of boring long holes on this kind of machine tool.
2. The coaxiality error of the column feeding into the turning boring hole and its compensation affect the main factors of the coaxiality of the turning boring hole of the milling and boring machine is the same as that of the desktop milling and boring machine, and it is also the indexing error da of the workbench rotation 180 ° turn and the half long hole D1 axis that has been bored before the turn is bored again, and the other half of the hole d2 of the long hole is bored again with the boring axis after the turn, and the positioning error dx2 of the required workbench moves Lx=2lx in the transverse (x) direction. Moreover, before and after the worktable rotates 180°, the inclination error DF generated by the table in the XY coordinate plane, the inclination error DY generated in the YZ plane and the translation error DY generated in the Y direction are also important influencing factors for the coaxiality of the turning head boring of the planer milling and boring machine. However, the influence of the spatial position of the axis of the boring shaft on the coaxiality of the turning boring hole is usually fed into the planer milling and boring machine that completes the full-length boring of the hole with a column, which is obviously different from the table-type milling and boring machine that is usually longitudinally transferred by the worktable.
3. Reasonable determination of the longitudinal position of the column when the boring shaft is fed
When encountering a specific situation, the milling boring machine must fix the column in a suitable position on the longitudinal bed, and when the boring shaft is stretched out with the cutter as the feeding form of the boring, the intersection angle error DB of the boring axis axis and the nominal axis of the boring hole in the XZ plane, and the intersection angle error DG in the YZ plane, the same as the desktop milling boring machine, has an important influence on the coaxiality of the turning boring hole, and with the increase of the feeding length of the boring shaft, the deflection of the boring bar caused by the self-weight of the boring shaft also has a great influence on the coaxiality of the turning boring. Unlike tabletop milling and boring machines, when the boring shaft of a planer milling boring machine extends out of the boring hole, the longitudinally movable column must be fixed in a definite position on the longitudinal bed, and it is important that this definite position can and should be selected.
4. Reasonable determination of the position of the cutter on the boring machine
When the column is used to feed the turning head boring hole on the boring machine, the boring cutter that is clamped on the tool holder of the boring shaft, the reasonable position along the Z direction, on the one hand, should meet the distance from the tip rotation center to the front end face of the spindle box is slightly greater than half of the total length of the hole (no matter how small, the long hole can not be bored, and the stiffness of the boring shaft decreases if it is too large);