Thermal temperature rise compensating method for numerical-control machine tool

Abstract

The invention discloses a thermal temperature rise compensating method for a numerical-control machine tool. In work of the numerical-control machine tool, a displacement sensor obtains elongation ofa rolling ball lead screw under each motion axis thermal temperature rise state of the numerical-control machine tool, and a corresponding mapping function is established according to a relationship between the elongation and a motion axis displacement error value; and a PMC system of a numerical-control system automatically calculates the error compensation value of each motion axis, and the numerical-control machine tool control system compensates motion axis displacement errors caused by thermal temperature rise. According to the thermal temperature rise compensating method disclosed by theinvention, the elongation of each motion axis lead screw thermal temperature rise is directly obtained by the displacement sensor, so that elongation data errors of rolling ball lead screw temperature rise are small, and precision is high; elongation data of the rolling ball lead screw temperature rise and the motion axis displacement error data are transmitted into the PMC of the numerical-control system to automatically calculate the error compensation value, and therefore, thermal temperature rise compensation precision is effectively improved, and product cost increase amount is smaller than 2%-3%. The method realizes solving the problems that processing precision of numerical-control equipment is reduced, a qualification rate of processed products is low, and the like as motion axispositioning errors are caused by motion axis transmission shaft deformation due to temperature changes with low cost.

Description

technical field [0001] The invention relates to the technical field of numerical control machine tools, and mainly relates to a method for compensating the precision of the numerical control machine tool for thermal temperature rise changes of the numerical control machine tool. Background technique [0002] When the CNC machine tool is working, there is relative motion between the transmission parts. The ball screw, ball screw nut, and bearing supporting the screw of the CNC machine tool will heat up under the action of friction, which will cause the moving parts, ball screw, ball The heat expansion and cold contraction of the screw nut will cause the change of the positioning error of the moving axis of the CNC machine tool. To solve the above problems, it is necessary to monitor the displacement of the thermal elongation of the moving parts, and calculate the positioning error value of the axis movement of the CNC machine tool according to the relationship between the dis...

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Problems solved by technology

[0003] To solve this problem, the traditional solution is to measure the temperature rise change of the ball screw through the temperature sensor, and then calculate the positioning error value of the axis movement of the CNC machine tool according to the relative relationship between the deformation of each transmission part and the temperature change, and compensate it to the CNC machine tool. In the system, this method is to obtain the deformation of the transmission parts indirectly. Due to the limitation of the machine tool mechanism, it may not be able to truly reflect the deformation of the transmission parts, which may lead to wrong compensation and lead to poor machining accuracy.

Another traditional method to solve the temperature rise and deformation of the transmission parts of CNC machine tools is to use a hollow oil-cooled ball screw. The oil cooler is designed with an oil temperature compensation system to keep the temperature of the ball screw within a certain temperature range. Effectively control the temperature rise of the screw rod, but the price is expensive

Another transmission method to solve the temperature rise and deformation of the transmission parts of CNC machine tools is to convert the semi-closed-loop control machine tool into full-closed-loop control by adding a grating ruler, but the price is expensive, especially on large-scale CNC gantry machine tools. The cost ratio is very high

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