| 摘要 |
PURPOSE:To improve operatability, by constituting a gear shiftable electric drill so as to select the optimum speed and gear ratio conditions with a microcomputer on a basis of drill diameter and workpiece material data. CONSTITUTION:Drill diameter and workpiece material data are inputted into a microcomputer 10 by a numerical designation switch 91 and a workpiece material designation switch 92 while the actual gear ratio is as well inputted into the microcomputer 10 via a gear condition detector 7. The microcomputer 10 displays some display data corresponding to the input on a display unit 93 while optimum gear ratio conditions and optimum speed are calculated and thereby the optimum speed data are outputted. Next, when the optimum gear ratio differes from the actual gear ratio, a gear shift signal is outputted and the gear combination of a redution mechanisn 5 is altered via a reduction selector 6. At this time, when a trigger switch 2 is turned on, a constant speed control circuit 12 controls the speed set by the microcomputer 10 into a constant speed. With this constitution, an electric drill automatically operates with the optimum speed so that operatability may be improved. |
