MAIN SPINDLE SPEED CHANGE SYSTEM OF NUMERICALLY CONTROLLED LATHE

摘要

PURPOSE:To shorten a time required to change a speed and improve the quality by providing a numerically controlled lathe, which has a main spindle mechanism with a stepless variable speed motor and a step variable speed gear, with a means to change the speed of a main spindle together with the switching of a step variable speed gear without stopping the main spindle. CONSTITUTION:For changing the speed of the main spindle of a numerically controlled lathe, this lathe is equipped with a step variable speed gear 2 (hereinafter referred to as ''mission''), a stepless variable speed motor 1 (hereinafter reffered to as ''motor'') connected to a main shaft 3 of this mission 2, a main shaft rotating speed detection sensor 4 to detect the rotating speed of the main shaft 3, and a main spindle speed change direction unit 5. In addition, it is equipped with an arithmetic unit 6 to perform operations for the direction of speed to the motor 1, a target main spindle rotating speed memory 10, an intermediate main spindle rotating speed memory 11, a decision unit 7 which judges whether or not the mission 2 needs to be changed with the speed change and, if it needs, judges again whether the mission 2 should be changed and the target speed should be directed or it should be changed to the intermediate main spindle rotating speed with the present mission, a motor control unit 8, and a mission change direction unit 9.