MACHINE TOOL

PROBLEM TO BE SOLVED: To provide a machine tool capable of easily suppressing chatter vibration during machining of a material and improving machining production efficiency of the material.SOLUTION: An automatic lathe 100 of a machine tool includes: a main spindle 10; a headstock 11; a spindle motor 12 for rotationally driving the main spindle 10; a turret 20 having a tool 30; and a control section 40 which has a rotation adjustment section 41 which controls the spindle motor 12 so as to adjust rotation of the main spindle 10. The rotation adjustment section 41 controls the spindle motor 12 so as to increase the number of the rotation of the main spindle 10 in inverse proportion to a machining residual length L2 of a bar material 50 held by the main spindle 10.SELECTED DRAWING: Figure 1 【課題】材料の加工時のびびり振動の抑制を簡易に行うとともに、材料の加工生産率を向上させることが可能な工作機械を提供する。【解決手段】工作機械の自動旋盤１００を、主軸１０と、主軸台１１と、主軸１０を回転駆動する主軸モータ１２と、工具３０を有するタレット２０と、主軸モータ１２を制御して主軸１０の回転を調節する回転調節部４１を有する制御部４０を備えて構成する。回転調節部４１は、主軸モータ１２を制御して、主軸１０の回転数を、主軸１０が保持した棒材５０の加工残長Ｌ２に反比例して増加させる。【選択図】図１