霸刀分享-外圆车削、端面车削、内孔车削，刀具选用指南！
（一）外圆车削
普通外圆车削是对零件的外圆表面进行加工，获得所需尺寸形位精度及表面质量。普通外圆车刀按照刀具主偏角分为95°、90°、75°、60°、45°等，90°、95°主偏角刀具切削时轴向力较大，径向力较小，适于车削细长轴类零件，75°、60°、45°主偏角刀具适于车削短粗类零件的外圆，其中45°主偏角刀具还可以进行45°倒角车削。负角刀片车刀经济性要好于正角刀片车刀，而正角刀片车刀刃口锋利，切削轻快，只是正角刀片尺寸一般比较小，只适于小背吃刀量、小进给量加工，而负角刀片尺寸可以制造的较大，可用于大背吃刀量、大进给量加工，刀尖强度也要好于正角刀片（相同形状、尺寸、刀尖圆弧的刀片）。不同形状刀片刃口强度不同，有效切削刃长不相同，可用刀尖数量也不同。
（二）端面车削
端面车削是指主切削刃对工件的端面进行切削加工。
1.车端面时注意事项
（1）车刀的刀尖应对准工件中心，以免车出的端面中心留有凸台。
（2）偏刀车端面，当背吃刀量较大时，容易扎刀。背吃刀量ap的选择：粗车时ap=0.5～3mm，精车时ap＝0.05～0.2mm。
（3）端面的直径从外到中心是变化的，切削速度也在改变，在计算切削速度时必须按端面的最大直径计算。
（4）车直径较大的端面，若出现凹心或凸肚时，应检查车刀和方刀架，以及大滑板是否锁紧。为使车刀准确地横向进给，应将中滑板紧固在床身上，用小刀架调整背吃刀量。
（5）端面质量要求较高时，最后一刀应由中心向外切削。
2. 车端面的质量分析
（1）端面不平，产生凸凹现象或端面中心留“小头”；原因是车刀安装不正确，刀尖没有对准工件中心，背吃刀量过大，车床有间隙滑板移动造成。
（2）表面粗糙度差。原因是车刀不锋利，手动走刀摇动不均匀或太快，自动进给量选择不当。
（三）内孔车削
内孔车削特性为：在半封闭状态下，不便于观察排屑情况，影响加工质量。深孔切削时常引起刀杆的振动，使得切削刃磨损快，小直径孔切削采用硬质合金刀杆，中等以上直径采用减振刀杆。进行外圆车削时，工件长度及所选的刀杆尺寸不会对刀具悬伸产生影响，因而能够承受在加工期间产生的切削力。进行镗削和内孔车削时，由于孔深决定了悬伸，因此，零件的孔径和长度对刀具的选择有极大的限制。
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Ba Dao Sharing- Tool selection guide for cylindrical turning, end face turning, and internal hole turning
(1) Outer circle turning
Ordinary cylindrical turning is the process of processing the outer surface of a part to obtain the required dimensional, positional accuracy and surface quality. Common cylindrical turning tools are classified by the main deflection Angle of the tool into 95°, 90°, 75°, 60°, 45°, etc. Tools with a main deflection Angle of 90° and 95° have a larger axial force and a smaller radial force during cutting, making them suitable for turning long and slender shaft parts. Tools with a main deflection Angle of 75°, 60°, and 45° are suitable for turning the outer circle of short and thick parts. Among them, the 45° main deflection Angle tool can also perform 45° chamfering turning. Negative-angle blade turning tools are more economical than positive-angle blade turning tools. Positive-angle blade turning tools have sharp cutting edges and smooth cutting. However, positive-angle blades are generally smaller in size and are only suitable for small depth of cut and small feed rate processing. In contrast, negative-angle blades can be manufactured in larger sizes and are suitable for large depth of cut and large feed rate processing. The strength of the blade tip is also better than that of the right-angle blade (blades of the same shape, size and arc of the blade tip). The edge strength of blades of different shapes varies, the effective cutting edge length is different, and the number of available tool tips is also different.
(2) End face turning
End face turning refers to the cutting process performed by the main cutting edge on the end face of a workpiece.
1. Precautions when turning the end face
(1) The tip of the turning tool should be aligned with the center of the workpiece to avoid leaving a protrusion at the center of the turned end face.
(2) When the depth of cut at the back is large, it is easy for the tool to be punctured when the end face of the off-center tool is turned. The selection of the depth of cut ap: For rough turning, ap=0.5-3mm; for finish turning, ap= 0.05-0.2mm.
(3) The diameter of the end face varies from the outside to the center, and the cutting speed also changes. When calculating the cutting speed, it must be based on the maximum diameter of the end face.
(4) When the larger diameter end face of the lathe shows a concave center or protruding belly, it is necessary to check whether the lathe tool and the square tool rest, as well as the large slide plate, are locked. To ensure accurate lateral feed of the turning tool, the middle slide plate should be securely fastened to the bed, and the depth of cut at the back should be adjusted with a small tool rest.
When the quality requirements for the end face are relatively high, the last cut should be made from the center to the outside.
2. Quality analysis of the vehicle end face
(1) The end face is uneven, resulting in a convex or concave phenomenon or leaving a "small head" at the center of the end face. The reason is that the turning tool was not installed correctly, the tool tip was not aligned with the center of the workpiece, the depth of cut was too large, and the clearance slide plate of the lathe moved.
(2) Poor surface roughness. The reasons are that the turning tool is not sharp enough, the manual tool movement is uneven or too fast, and the automatic feed rate is improperly selected.
(3) Inner hole turning
The characteristics of the inner hole turning are as follows: In a semi-closed state, it is not convenient to observe the chip removal situation, which affects the processing quality. Deep hole cutting often causes vibration of the tool holder, which leads to rapid wear of the cutting edge. For small-diameter hole cutting, hard alloy tool holders are used, while for medium and larger diameters, vibration-damping tool holders are adopted. When performing cylindrical turning, the length of the workpiece and the selected tool holder size do not affect the tool overhang, and thus can withstand the cutting force generated during the processing. When performing boring and internal hole turning, since the hole depth determines the overhang, the hole diameter and length of the part impose significant restrictions on the selection of cutting tools.