tailieunhanh - Cảm biến trong sản xuất P17

Sensors used for ultra-precision machines include position and velocity sensors, which are mostly part of a control loop, and for some special applications acceleration sensors for active vibration control, and thermal sensors for thermal error compensation [1]. An essential component of each positional feedback loop in a machine tool is the displacement measurement system for detecting the actual position of moving machine parts. It is the performance of such measurement systems that limits the accuracy of machine tools and hence directly affects the quality of the machined part. | Sensors in Manufacturing. Edited by . Tonshoff I. Inasaki I 343 Copyright 2001 Wiley-VCH Verlag GmbH ISBNs 3-527-29558-5 Hardcover 3-527-60002-7 Electronic 5 Developments in Manufacturing and Their Influence on Sensors Ultra-precision Machining Nanometric Displacement Sensors E. Brinksmeier Universität Bremen Bremen Germany Sensors used for ultra-precision machines include position and velocity sensors which are mostly part of a control loop and for some special applications acceleration sensors for active vibration control and thermal sensors for thermal error compensation 1 . An essential component of each positional feedback loop in a machine tool is the displacement measurement system for detecting the actual position of moving machine parts. It is the performance of such measurement systems that limits the accuracy of machine tools and hence directly affects the quality of the machined part. In ultra-precision machining accuracies of interest are of one part in 106 or even 107 with a measurement range of up to 1 m. Adequate resolutions are in the range of nanometers 2 . Such demands can only be fulfilled by laser interferometers optical scales and linear voltage differential transducers which will be covered in detail. Although capacitive and piezoresistive sensors are able to offer resolutions in the sub-nanometer range their measurement range is rather small which limits their application to measuring macroscopic workpieces 1 . Optical Scales Optical scales are based on a repetitive pattern of reflective or transmissive material. On scanning along the scale a periodic signal is obtained which is a direct measure for the traveled path. Conventional optical encoders also called photoelectric encoders are based on counting Moiré lines by means of a light source and a photodiode. Beside optical scales the patterns might also be made of magnetic or conductive material. The principle is then based on magnetic capacitive or inductive measurement 2 3 .