THE EFFECT OF HEAT GENERATED BY FRICTION IN THE  BALL-SCREW-NUT SYSTEM ON THE PRECISION OF HIGH SPEED MACHINE

Aziz Muhammed, Mahmmod

	THE EFFECT OF HEAT GENERATED BY FRICTION IN THE BALL-SCREW-NUT SYSTEM ON THE PRECISION OF HIGH SPEED MACHINE
AL-TAQANI
Article 1, Volume 24, Issue 6, 2011, Pages 112-123
Author
Mahmmod Aziz Muhammed
Abstract
High Speed Machining (HSM) offers the promising choice for increasing industrial demands. However, HSM implies more reciprocating movement in machine tool axes. Friction forces, which occur in highly speed moving components, such as ball-screw assembly subjected to linear motion, will induce heat. Factors such as cutting forces, material weight, feeding acceleration, etc, decide how much heat that will be generated and accumulated. On the other hand, positioning sensor used in HSM, which detects machine position by means of rotary encoder that is mounted on the same axis with the screw-nut assembly, is mostly indirect positioned. Machine position is determined by converting rotary encoder signal and ball screw's lead into linear translation position. Accordingly, positioning error will occur when lead is not uniform in motion or there is a change in lead when machine is being operated. In this research, heat generation due to friction forces induced in the ball-screw-nut assembly is studied. The aim is to understand the phenomenon of heat accumulation that may affect positioning errors due to lead-elongation. Additionally, the deformation caused by temperature increase is estimated based on temperature distribution within the ball-screw assembly which is determined numerically applying the conventional finite difference method.
Keywords
HSM; Heat generation; Friction; ball; screw assembly; positioning error; Finite Difference Method

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