Metal machining and drilling bits
OwnerDavid Mugeliinventor
Life of this patent
Estimating the term…
Abstract
The drill (20) include a shear off safety feature. The flats (21) are connected to the bit (22) via a wasted section (23) so that upon jamming of the bit in a workpiece the wasted section will twist and shear off releasing the operator. The shank of the bit is made long enough that even if it is sheared there is still enough shank so that the but may still be used to complete a drilling procedure if this be required. The shear torque is typically 15-30 ft lbs. Preferably 15-20 ft lbs for domestic drills and 20-30 ft lbs for industrial drills.
Claims33
A rotary bit with a shank adapted to locate in a chuck, the shank having an insert end and an end section extending from the insert end, the end section having at least one elongate flat which locates inside the chuck when the shank is operatively engaged in the chuck, and a wasted safety section spaced from the insert end by a spacing, the spacing of the wasted safety section from the insert end being sufficient so that when the shank is operatively engaged in the chuck, the wasted safety section is outside the chuck, the wasted safety section having a predetermined shear torque rating so that the shank shears at the wasted safety section if the predetermined shear torque rating is exceeded, wherein the shank includes a further flat outboard of the wasted safety section so that after the wasted safety section has been sheared, if necessary, a user may still use the bit on a temporary basis to complete a drilling task.
(canceled)
Dependencies are inferred from the claim text.