A seven-sensor configuration method for testing thermal error of a horizontal machining center with linear optical grating scale

Abstract

A precision testing method based on a seven-sensor configuration is presented in this paper to quantify thermal errors (drifting, elongation, tilting) of the mandrel cross-section, for an example horizontal machining center with linear optical grating scale. Three tri-axial displacement sensors with 120° spread angles and 36 thermal couples are mounted on judiciously chosen locations to record the temperatures and thermal expansions for various operating conditions. Based on the measurements covering a wide range of spindle locations, environment temperatures, coolant temperature, and spindle rotational speeds, we found that (i) the maximum thermal drifts of the mandrel are 11.3 µm in the x direction with a compensation rate of 62%, and 165.3 µm in the y direction with a compensation rate of 93%, (ii) the maximum thermal tilt of the mandrel is 0.005°, and (iii) the thermal elongation of the mandrel in the z direction, which could not be compensated by the linear optical grating scale, is 51.9 µm. From a correlation study, the thermal elongation of the mandrel is most closely correlated to the temperatures recorded for the thermal couple mounted at the front surface of the spindle bearing with a correlation coefficient of 0.83.

Analysis of Thermal Error Model of Ball Screw Feed System Based on Experimental Data

“…(27) Then we use the constant variation method to solve the special solution of Eq. (26).Supposed C1=h(t),the Eq. ( 27) can be expressed as follows:…”

Analysis of thermal error model of ball screw feed system based on experimental data

“…Experimental facilities verified the feasibility of its proposal. Sun [26] presented a precision testing method called seven-sensor configuration method to measure the thermal errors of a horizontal machining center with linear optical grating scale. Li [27] tests the temperatures and positional deviations of the ball screw feed drive system and the linear motor feed drive system equipped with linear scales, and analyzes the factors that affect the positioning error.…”

Experiment-based thermal behavior research about the feed drive system with linear scale

“…The effects of aluminum extrusion, glass scale, and the adhesive on the thermal elongation of the linear grating scale were examined. Sun et al 18 presented a precision testing method called seven-sensor configuration method to measure the thermal errors of a horizontal machining center with linear optical grating scale. Based on testing and finite element analysis, Kim et al 19 studied the thermal error induced by the thermal expansion of the linear grating scale in a horizontal machining center equipped with linear motors.…”