In CNC lathe processing shaft parts, whether processing the outer circle or the inner hole, it is inevitable to produce taper. The size of the workpiece processed is inconsistent with the diameter tolerance at both ends. The size of one end is large and the size of the other end is small, which makes the processing size beyond the tolerance range. This is the most common defect in the process of NC turning. The main reasons for the taper are as follows:
1. The lathe is not level, the four corners of the machine tool and the center of the bed anchor bolts and adjusting pads are loose, resulting in the horizontal straightness of the guide rail surface and the inclination in the vertical plane seriously exceed the standard. Make the spindle axis and guide rail is not parallel, the size of the head phenomenon.
2. The guide rail of the bed is worn, so that the path of the turning tool is not parallel to the axis of the workpiece.
3. The clearance between the spindle and the bearing is too large, affecting the machining accuracy of the workpiece.
4. Before turning, the back center is not aligned with the spindle axis, resulting in offset.
5. The rigidity of the turning tool is insufficient, and the occurrence of letting the tool in the process of processing will lead to the diameter of the tail seat less than the diameter of the chuck direction.
6. Under the condition of intact machine tool, influenced by the geometric Angle of the tool, the radial cutting force FV is large, the cutting deformation is large after processing, and the workpiece will also form taper.
There are the following solutions to eliminate the accidental taper:
1. Check and measure the accuracy of the machine tool, and correct the parallelism between the spindle axis and the guide rail of the bed.
2. Before turning, find the back center and make it coaxial with the main shaft axis.
3. Replace the tail seat sleeve with a new one.
4. Choose the tool with good rigidity and easy fastening.
5. Choose geometric Angle of turning tool reasonably.