Nihon Kikai Gakkai ronbunshu (Sep 2017)
Time domain coupled simulation of machine tool dynamic behaviour and cutting force based on voxel simulator of machining operation
Abstract
It is known that the cutting force excites the structural vibration of machine tool. In addition, cutting force acts on feed and spindle drive system as a force disturbance, and feed speed and spindle speed are changed. As the results, cutting force is also changed because the depth of cut and cutting speed are changed due to the machine vibration, feed and spindle speed changes. The purpose of this study is to analyze the coupled vibration between the machine tool behavior and the cutting force. In order to achieve the purpose, in this study, a coupled simulation method of the vibration of machine tool, the dynamic behaviors of feed and spindle drive systems and the cutting force is developed. Cutting force and machined surface geometry is simulated using the voxel simulator in which the workpieces is represented by voxels. Undeformed chip thickness can be calculated based on the relative position between the tool and workpieces, and the tool rotational angle at the each time step based on the voxel model. The cutting force is estimated based on the calculated undeformed chip thickness. The relative position between tool and workpiece at each time step is simulated by the feed drive system and machine tool structural models. The tool rotational angle is simulated by the spindle drive system model. The coupled simulation between the cutting force, structural vibration of machine tool and feed and spindle drive systems is carried out by applying the simulated cutting force and cutting torque as a disturbance to the feed and spindle drive systems and machine tool structure. Cutting tests and simulations are carried out with two kinds of radial depth of cut, 5 mm and 20 mm. It is confirmed that the machine tool dynamic behaviors due to the cutting force and torque which is also influenced by the machine tool behaviors can be simulated by the proposed method. It is also confirmed that the chatter vibration which is observed in case of the 20 mm depth of cut can be simulated by the proposed method.
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