Importance

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Abstract

A tap drive unit for machine tools, which is coupled to the machine-head of the machine tool such as a machining center, includes a driver detachably coupled to a main spindle of the machine tool so as to be rotated with the main spindle, a support member for rotatably supporting the driver, the support member being fixedly mounted on a stationary portion of the machine tool when the driver is coupled to the main spindle of the machine tool, a tubular guide member supported by the support member so as to be concentric with the driver, and a rotational shaft on one end of which a tap is mounted. The guide member is axially moved when a load larger than a predetermined value acts on it. An internal thread is formed in the inner periphery of the guide member. An external thread is formed in the outer periphery of the rotational shaft so as to be threadably engaged with the internal thread. When the main spindle of the machine tool is rotated, the rotational shaft is axially moved in accordance with the pitch of the tap by the interaction of the internal and external threads. Obstruction of the downwardly axial movement of the tap applies a load upon the guide member which then moves upwardly and operates a mechanism to reverse the direction of the spindle.

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First Claim