| 摘要 |
386,055. Speed control for drilling- machines. ASQUITH, Ltd., W., Highroad Well Works, and FEATHER, G., Wells by House, Highroad Well, both in Halifax, Yorkshire. Oct. 8, 1931, No. 27935. [Class 83 (iii).] An indicator for a drilling-machine for enabling an operator to see the correct speed for drills of different sizes and also the cutting speed comprises an arm a fixed to the changespeed shaft B of the spindle-driving gearing and terminating in an aperture A which moves over a drum C which is rotatable about the axis of shaft B by worm gearing c<3>. The surface of the drum is marked with drill sizes arranged in geometrical progression to conform with thirtysix spindle speeds, these speeds being obtained by rotary and longitudinal movements of the control shaft B. These speeds are indicated on a fixed plate e. The drum is also marked with cutting speeds which are observable through an aperture e<2>. In operation, if for instance a cutting speed of 60 feet per minute is to be used with a drill of 3<5>/16" diameter the drum is rotated until the 60 is observed in the aperture e<2> and the shaft B is moved until the indicator A is over the 3<5>/16" mark on the drum. This automatically selects the required spindle speed which by reference to the table e is seen to be 68 revolutions per minute.
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