Study of the Effect of Friction on the Errors of the Stopping Position of the Automatic Tool Changer on CNC Machine Under Variable Relative Humidity Conditions

Abstract

AbstractAn automatic tool changer (ATC) is an important module on computer numerical control (CNC) machine, it determines the level of automation and flexibility of the machine. Accurate stopping at the position of the ATC during the tool change process would minimize the damage of the taper hole and ensure the machining quality of the product. In a CNC machine, the motion of ATC to the tool change position is performed by a pneumatic cylinder. Friction, in which its behavior is complex and depends on many factors such as pressure, velocity lubrication, etc., always embarrasses controlling of the position of the ATC. This paper presents the effect of friction on the stopping position error of the ATC on the CNC machine under conditions of relative humidity (RH) varying from 51% to 99%. The study results showed that the stopping position error of the pneumatic cylinder depends on the number of tools stored in the ATC and tends to increase when the relative humidity and the travel speed increased.KeywordsPosition controlPneumatic positioning systemFrictionHumidity relativeAutomatic tool changeCNC machine