Theoretical And Experimental Investigation On Fast Tool Servo Integrated With Cutting Force Measurement

Fast tool servo(FTS)can achieve cutting tool's rapid and reciprocating motion relative to the workpiece.FTS is widely used in precision and ultra-precision processing of non-axisymmetric optical free-form surface and machine tool error compensation.Cutting force has a great effect on machining quality.For error compensation based on FTS and free-from surface machining by FTS,cutting force measurement is necessary.Measuring cutting force correctly contributes to indicate machining principle of FTS.Therefore,it is necessary to integrate cutting force measurement in machine apparatus used for single point diamond turning based on FTS.There are two measuring methods for turning cutting force at present.One is installing measuring apparatuses on principal axis,the other is installing measuring apparatuses on tool apron.FTS is a flexible mechanism and cutting depth of FTS changes in a high frequency in machining process,present international schemes can not achieve effective cutting force measurement.How to measure cutting force correctly is a problem demanding prompt solution now.This paper evaluates international research on FTS,mainly involving working principle,structure,type,development process and application prospect of FTS,and analyzes present international typical FTSs with cutting force measurement.To measure cutting force correctly,based on the FTS with Y and Z directional cutting force measurement,measure error analysis of cutting force is carried out.Design principles of FTS with cutting force measurement are concluded.The relationship between dynamic parameters and cutting force measuring error is analysed.A FTS with three directional cutting forces measurement is developed.Its performance of measuring three directional cutting forces is verified by calibration tests.Cutting force online is acquired by turning tests.Research contents of this paper as follows.1.Cutting force measurement accuracy of FTS with front force sensor and FTS with rear force sensor are compared.A FTS with Y and Z directional cutting force measurement is designed.A method for force measuring error analysis is presented.2.A FTS with three directional cutting forces measurement is developed.Cutting force measurement scheme of isosceles triangle arrangement(T-type)of three force sensors is proposed.Through analyzing the cutting force measurement,three directional cutting force measuring modeling is established.Based on frequency response function,an error compensation for cutting force measurement is presented.3.A 4-DOF gantry-type vibration exciter is developed and can apply force in different frequency in every direction.A series of off-line tests for FTS with three directional cutting force measurement are carried out.Working performance and cutting force measuring ability are testified.4.Three directional static calibration systems are established.Cutting force measuring errors in vibration exciter experiment are calculated.Different planes and optical free-form surfaces are machined and relevant cutting force signals are collected.The contributions of the paper are presenting a cutting force measuring error analysis calculation method and developing a FTS with three directional cutting force measurement and an error compensation method.