Causes for Changing the Construction Properties of a Machine-Tool under Heat Exposure

According to the current trends in the field of mechanical engineering the machine-tools are characterized by high available power, by concentration of actions for the manufacture of workpieces on one machine-tool, and also by high cutting speeds, high feed rates, etc. Machine-tools equipped with various devices that provide automated support processes. During the operation all of the above is accompanied by heat due to which the construction, which subjected to heat exposure, changes the stiffness of load-carrying system. To reduce the level of exposure it is necessary to know the root cause for stiffness changing. The first works in this field stated the presence of the phenomenon. Later the cause for stiffness changing and mechanism of the process for said changing in the spindle bearings were defined. However, this cannot explain the mechanism for stiffness changing in overall. This paper attempts to explain the process for stiffness changing. It is found that the stiffness changing is caused by the motion in construction due to heat exposure. The study showed that the stabilization of geometric accuracy of construction is essential, but not sufficient to ensure the accuracy of the machine-tool. For stiffness stabilization of the machine-tool construction it is required to stabilize the state of its moving and fixed joints throughout the construction.

References

[1] Endzheevski E., Kvas’ny V. Vliianie teplovykh izmenenii zazora v podshipnikakh kacheniia na zhestkost’ shpindel’nykh uzlov [The effect of thermal changes of the gap in rolling the stiffness spindles]. Stanki i instrumenty [Tools and Instruments]. 1977, no. 4, pp. 10–12.

[2] Levina Z.M., Reshetov D.N. Kontaktnaia zhestkost’ mashin [Contact stiffness machines]. Moscow, Mashinostroenie publ., 1971. 264 p.

[3] Tochnost’ mekhanicheskoi obrabotki i puti ee povysheniia [Machining accuracy and ways to improve it]. Ed. Sokolovskii A.P. Moscow, Leningrad, Mashgiz publ., 1951. 487 p.

[4] Bazrov B.M. Tekhnologicheskie osnovy proektirovaniia samonastraivaiushchikhsia stankov [Technological basis for the design of self-adjusting machine]. Moscow, Mashinostroenie publ., 1974. 216 p.