In the process of precision mechanical parts processing, we are obviously more concerned about accuracy. There is a type of parts whose length to diameter ratio is greater than 20. We call this kind of parts a slender shaft. When turning precision slender shafts, under the action of cutting force and cutting heat, due to its poor rigidity, such parts are prone to bending and deformation. The processed slender shafts are thick in the middle and thin at both ends, which affects the accuracy of precision mechanical parts processing. .
At the same time, after the precision slender shaft is bent and deformed, it will also cause vibration, thereby affecting the surface roughness of the part. When we are processing this type of parts, we need to take some measures to reduce this deformation. When adopting the clamping method of one clamp and one top, the tip should be an elastic movable tip, so that the slender shaft can be stretched freely after being heated, so as to reduce its bending deformation when heated.
At the same time, an open traveler can be inserted between the jaws and the elongated shaft to reduce the axial contact length between the jaws and the elongated shaft, eliminate over-positioning during installation, and reduce bending deformation. The slender shaft is turned with one-clamp and one-top clamping method. In order to reduce the influence of radial cutting force on the bending deformation of the slender shaft, the tool holder and center frame are traditionally used, which is equivalent to adding a support on the slender shaft. , Increase the rigidity of the slender shaft, which can effectively reduce the influence of the radial cutting force on the slender shaft.
However, this method cannot solve the problem of bending the workpiece by the axial cutting force, so the axial clamping method can be used to turn the slender shaft. Specific operation: When turning a slender shaft, one end of the slender shaft is clamped by a chuck, and the other end is clamped by a specially designed clamp pull head, which applies axial tension to the slender shaft.
In the turning process, the slender shaft is always subjected to axial tension, which solves the problem of bending the slender shaft by the axial cutting force. At the same time, under the action of the axial tension, the slender shaft will be caused by the radial cutting force. The degree of bending deformation is reduced, the axial elongation caused by the cutting heat is compensated, and the rigidity and machining accuracy of the slender shaft are improved.
The precision slender shaft is turned by the reverse cutting method. The turning tool is fed from the spindle chuck to the tailstock direction, so that the axial cutting force generated during the machining process causes the slender shaft to be pulled, eliminating the axial cutting force. At the same time, the use of elastic tailstock tip can effectively compensate the compression deformation and thermal elongation of the workpiece from the tool to the tailstock section, and avoid the bending deformation of the workpiece.