| CPC B23Q 17/0957 (2013.01) [B23B 1/00 (2013.01); B23B 2270/48 (2013.01)] | 9 Claims |
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1. A lathe comprising:
a spindle capable of releasably holding a bar material;
an opposite spindle capable of releasably holding an end of the bar material protruded from the spindle;
a tool post on which a cut-off tool is removably attached to cut off the bar material held by the spindle so as to separate the end of the bar material from the bar material;
a controller adapted to control operations of the spindle, the opposite spindle, and the tool post; and
a contact-type breakage detector provided with a sensor retractably advancing to an advancing position where the sensor could hit the end of the bar material if it remains after the cut-off tool cuts off the bar material, the contact-type breakage detector being capable of detecting breakage of the cut-off tool if the sensor hits the end of the bar material in the advancing position,
wherein the controller performs a non-mechanical-type breakage detection to determine whether the cut-off tool is broken according to a control parameter for controlling at least one of the spindle and the opposite spindle to make the spindle and the opposite spindle move away from each other at a first detection timing immediately after the cut-off tool cuts off the bar material while the opposite spindle holds the bar material held by the spindle, and performs a mechanical-type breakage detection to determine whether the cut-off tool is broken according to a detection result by the contact-type breakage detector at a second detection timing different from the first detection timing.
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