Mathematical modeling of machine tools’ guideway wear
Engineering Education # 04, April 2013
This article is devoted to the development of methods of mathematical simulation techniques for modeling machine tools’ guideway wear. An example of calculation of pressure curves in the edges of the machine tool’s guideways was presented; values of pressure were determined according to the scheme of the forces and reactions. The fundamentals of method for calculating wear of guideway friction pairs developed by prof. A.S. Pronikovd were considered. Possibility of improving the method was demonstrated for the case, when greater accuracy for modeling wear process is required. Algorithm of wear simulation with the possibility of calculating guideways wear with any complexity of changes in pressure curves along the trajectory of working body on the bedplate. The only requirement for the calculation is that the pressure curve remains constant at the elementary step of modeling. Experimental data which verify the accuracy of modeling by the example of study of the wear process of guideways and changes in the trajectory of the movable working body of machine tools under operating conditions were also presented in this article.
Prediction of loss of accuracy in machine tools
Engineering Education # 05, May 2013
This author considers development of techniques for predicting loss of accuracy in machine tools with guideway wear. The problem of obtaining sufficient accuracy for practical estimation of the resource mean value and its possible dispersion was described. The Monte Carlo method, which is currently used for solving this problem, was investigated; its main disadvantages were listed. A basic description of the main stages of the new method for predicting loss of accuracy in machine tools in case of guideway wear was presented with an example of realization of these stages. The author also presents results of predicting loss of accuracy for 16K20F3 and STP-220AP machine tools, which were obtained after cycles of static simulation of wearing process of guideways in case of sufficiently accurate determination of distribution density of resource probability over accuracy parameters.
Test of the machine-tools for implementing high-speed cutting
Engineering Education # 06, June 2013
This article presents prerequisites for carrying out experiments in order to test machine tools for implementing high-speed processing. The authors propose a method for determining frequency vibration-free tool rotation at high speed milling. Results of experiments of measuring cutting forces with the use of the Kistler dynamometer are presented in this article. They are: turning of aluminum alloy at cutting speeds from 100 to 1000 m/min at Swiss Federal Institute of Technology Zurich; milling of aluminum alloys at cutting speeds from 471 to 942 m/min at Bauman MSTU, Laboratory of Department MT-1 “Machine Tools”; milling of aluminum alloys and steels (cutting speed up to 452 m/min) at Dubna Machine Building Plant.