Development of real-time volumetric error compensation system for 3-axis Machine Tools
Date Issued
2014
Date
2014
Author(s)
Yen, Han-Ming
Abstract
The position feedback control of NC machine tool controllers mostly employs displacement sensor (such as optical scale or encoder) as a single sensor system. Distance between axis of sensor and axis of cutting could lead to massive enlargement of the positioning error of each axis which is known as the Abbe principle. The movement of linear stage inherently has position and orientation errors in six degree of freedom, which are three linear errors (positioning error, horizontal straightness and vertical straightness) and three rotational angles (pitch, yaw and roll). As a result, Abbe error is considered to be the major cause for volumetric error of machine tool. In this study, a multi-sensor feed-back compensation system which consists of three angular sensors and NC controller is developed to greatly enhance the machine tool accuracy by detecting angular errors in real-time and corresponding Abbe offsets so as to compensate for the Abbe errors dynamically. It can also be embedded in NC controllers to improve the accuracy of machine tool. In the measurement system, autocollimator and roll are deployed to monitor the angular errors of machine tool by constantly converting the measuring signals into Pc-based controller(with embedded volumetric error model) Experiments show that the positioning error of an investigated NC machine tool Fis mainly affected by Abbe error. With the proposed volumetric error compensation system, the positioning accuracy can be significantly improved by more than 80%.
Subjects
NC machine tool
Abbe error
real-time volumetric error compensator
three angle sensor
Type
thesis
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