| The length to diameter ratio less than 0.05 is called the slender shaft in the shaft. Because the slender shaft turning processing is vulnerable to bending displacement amount, the changing of cut back size, its own gravity and clamping pattern, which make processing difficult. In order to meet the needs of modern society, the surface quality of the slender shaft parts requirements is increasing. Studies have shown that the main factors of slender shaft turning accuracy are vibration and bending displacement amount, so it is important to reduce the bending displacement amount and vibration in slender shaft turning to improve the quality. Research the influence of changing cut back the size to slender shaft radial force, which affects the displacement amount during the slander shaft processing, the greater bending degree, the more obvious vibration. This will affect the tool life and the surface quality of slender shaft during the machining. It is important guarantee to using the effective way to reduce bending displacement amount and vibration in the slender shaft turning processing for improving slender shaft turning accuracy.This paper mainly studies the influence on three-knife distribution 120° lathing to slender shaft turning accuracy, deducing slender shaft deflection curve function and mechanical equilibrium equation during three-knife turning by establishing slender shafts turning model. In order to solve the accuracy of force measurement during turning, this paper offers the force measuring device of three-sensor voltage to measure accurately in three-knife turning, through the analysis on the principle of the strain sensor.With the research on cut back size in three-knife turning and dual-tools turning by DEFORM software, this paper draws images and analysis, gets the results that three-knife slender shaft effectiveness is smaller than ordinary turning and dual-tools turning, turning vibration reduces significantly. It will measure the radial and axial force, shear force of the ordinary turning and three-knife turning with three-force measuring device.This paper solves the overall stiffness matrix of three-knife slender shaft using finite element theory, and static analysis to slender shaft by ANSYS software, get slender shaft turning vibrations and natural frequencies. It will analyze three-knife bending size chart, to prove the feasibility of the previous derived theoretical formula in this paper, and deduce the relieving amount curve by using full method to be transient kinetic analysis.After analyzing the influence of cutting back force to slender shaft vibration with three different turning methods, by measuring different nodal forces of node numbers 11, 41, 71, 101 and displacement maps to get the range of optimal cut back amount and the relieving amount with tri-tools turning, this paper gets more accurate conclusions, comparing with the derivation theoretical formulas. It proves that three-knife turning makes turning force balance each other, and reduces the force of bending displacement amount and vibration, which is applied to the slender shaft, through analysis three-knife turning, dual-tools turning and ordinary turning. |
