Modeling And Analysis Of Cutting Force In Turning Process Of Freeform Surfaces Based On Fast Tool Servo

Fast tool servo(Fast tool servo, FTS) is installed in a supplementary motor axis on the lathe which not only can realize the cutting tool along the x and z axis rapid reciprocating linear motion, but also can realize the rapid and reciprocating swing around the axis B. However "Fast" is a relative concept, mainly refers to the movement than traditional directly using the lathe axis reciprocating motion can obtain a higher frequency; "Server" is emphasized the trajectory tracking control of the cutting tool. FTS mainly involves the following three aspects of engineering application:(1) Turning the non-symmetry shaft or hole parts.(2) Turning the non-symmetry optical free surface or microstructure surface parts.(3) Active compensation comprehensive error of machine tool, especially the not drab part of the error. It can effectively solve the large inertia motion axis machine tool can’t rapid reciprocating motion and the divergence problem when axes error compensation. Due to the system of adoption FTS turning is mainly used for precision or ultra-precision machining and the work-piece surface quality has a higher request, therefore is necessary for the formation of the cutting force and the modeling more in-depth and thorough research. Establish effective cutting force model will help us better realized the servo cutting process, the tool wear mechanism at the same time allow us to have better understanding to fast tool servo cutting mechanism and design has important significance.There is a big difference between fast tool servo and the traditional turning, the main difference is summarized as the following two aspects:(1) Quick and reciprocating change alternating cutting force Which “change” is reflected in two aspects of the direction of the cutting force and cutting thickness.(2) Because of the cutting parameter of FTS system is at the micro or nanometer level so the tip blunt round radius and circular arc surface of cutting edge will have a significant impact to cutting force. In order to solve above problem this paper developed a cutting force model based on orthogonal cutting that introduction of rank angle and tool radius.The main work of this article is as follows:1. Base on Fast Tool Servo cutting process and cutting characteristics, established a cutting force model based on orthogonal cutting compound which introducing rounded corners, tip blunt, that is a different depth of cut with different cutting mechanism for cutting force forecast. At the same time, respectively on the tool rake face, blunt tip half portion and the lower half of the tip blunt cutting force obtained using analytical method prediction value.2. Based on the theoretical model of cutting force by cutting force of Matlab simulation, but also analyzes the model parameters on cutting force changes of size.From the point of view of numerical analysis validated the accuracy and reasonable trends of the cutting force model.3. Design a single degree of freedom FTS with function measurement of the cutting force that resolved the problem of the FTS cutting force measurement difficulties and inaccurate. Since this design by FTS original intention was to experimentally verify the accuracy of the model further, so FTS practicality and reliability must be reliable that Single degree of freedom of design with respect to two degrees of freedom, three degrees of freedom FTS reliability will be greatly improved.designed FTS in this article is reasonable arrangement of the pressure sensor position,can effectively measure the Y direction(the direction of the main cutting force)cutting force, so compared to other load FTS, effective, accurate measurement of cutting forces will be more meaningful.