| 摘要 |
<p>In a power screwdriver-drill for clinching hollow cylindrical inserts (50) with a flanged end (52) and an internally threaded end (53) interconnected by an collapsible centre section (54), use is made of an interchangeable bolt (7) having one end (8) threaded to match the internal thread of the insert and coupled coaxially by the remaining end (9) to a prismatic spindle (3). The motor (2) is governed by an electronic monitoring and control unit (10) wired into the power supply line (6) between the on-off switch (5) and the motor, which regulates the input voltage to a value reflecting the maximum torque requirement and comprises a transducer (13) of which the output signal, a continuous voltage proportional to the current absorbed by the motor, is used to pilot a device (14) capable of inverting the polarity of the power supply to the motor (2), and thus automatically reversing its direction of rotation, on sensing a current equal to or greater than that absorbed by the windings when sufficient power is developed to give optimum upsetting and clinching torque at the spindle (3). <IMAGE></p> |
