| 摘要 |
Automatic apparatus for tapping bores and holes, comprising an electric motor adapted to rotate in both directions of rotation to rotatably drive a chuck carrying a tapping tool; there are provided means that are adapted to detect, during the displacement travel of the chuck, the moment or the position of the same chuck when the resistance to rotation rises above a pre-established value. These means comprise a sensor for measuring the instant power input of the electric motor, as well as comparator means for comparing the instant power input measured with a reference value corresponding to the motor power input when the resistance to the rotation of the chuck reaches up to said pre-established value. Upon reaching this value, the chuck keeps rotating and displacing until the number of revolutions performed by the same reaches a pre-determined number, after which the motor reverses its direction of rotation so that the tapping tool is automatically unscrewed and withdrawn from the tapped bore.
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