"The lathe is afraid of the rod." This sentence reflects the difficulty of turning slender rods. Due to the characteristics and technical requirements of the slender shaft, when turning at high speed, it is easy to produce defects such as vibration, polygon, slub, cylindricity difference and bending. If you want to drive it smoothly, you must pay full attention to the problems in the process.
1) Machine tool adjustment
The connection between the center line of the lathe main shaft and the tailstock must be parallel to the top, bottom, left, and right of the large lathe guide rail, and the tolerance should be less than 0.02mm.
2) Workpiece installation
When installing, try not to cause over-positioning. When clamping one end with a chuck, do not exceed 10mm.
3) Tool
Adopt κr = 75 ° ～ 90 ° partial knife, pay attention to the secondary angle α′0≤4 ° ～ 6 °, it should not be large. When the tool is installed, it should be slightly higher than the center.
4) Following the knife holder, it must be trimmed after installation
The method of dressing can be grinding, reaming, boring, etc., so that the arc surface contacting the tool holder claw and the workpiece R≥ the radius of the workpiece, and it must not be smaller than the radius of the workpiece to prevent the occurrence of multiple edges. When adjusting with the tool holder claw, make the claw contact with the work piece, do not apply force to prevent the slub.
5) Auxiliary support
When the length-to-diameter ratio of the workpiece is greater than 40, an auxiliary support should be added during the turning process to prevent the workpiece from vibrating or centrifugal force to throw the workpiece. Pay attention to the adjustment of the top during the cutting process, it is better to just top the workpiece, not tight, and adjust at any time to prevent the workpiece from thermal expansion, deformation and bending.
