The Design And Development Of Thermal Modal Testing Instrument

With a comprehensive understanding of the history of CNC machine tools’ thermal error studying, this paper focuses on the following contents.A new system based on thermal modal theory i.e."Thermal modal testing instrument" is developed. This new system is able to implement the temperature measurement, thermal error calculating, displaying and compensation at the same time. The temperature of as many as16key points can be synchronously measured and displayed. Thermal error is calculated and transported into the CNC controller by methods of the generalized time constant and temperature rising model. Programmable touch screen is selected as the man-machine exchange equipment to make the system easier for users to set up parameters and to observe the results in real time. Moreover, the capability of connecting external storage devices such as USB makes the system a convenient and powerful tool for thermal error studying.In order to extend the performance of the instrument, a set of software based on MFC programming named "Thermal modal analysis software" is developed. This new software calculates the thermal eigenvalues of the CNC system by the time domain construction algorithm, which is able to forecast the temperature rising curve and thus improve the efficiency of the study of CNC machine tools’thermal error studying. With the thermal modal system mentioned above, several experiments are conducted. This system is able to forecast the temperature rising curve with a fitting error less than3%.In the Comprehensive error compensation experiment for a horizontal machining center, the system also demonstrates its ability to reduce more than70%of the contour error.