Hand drill and drive assembly - has specified thread lead in spindle and tool-end union thread for friction effect

摘要

Hand drill and power drive assembly consists of a torque and impact transfer spindle with female thread to accept the male threaded end of the screw-in drill tool. The connection thread thus formed has a lead angle of 'alpha' whose tangent is equal to or exceeds the static friction factor (mu) of the tool screw-in end against the material of which the spindle is made. Preferably the tool end is steel, through plastics is also proposed. Adjoining the thread there should be a locking ring made from material of higher friction than the end of the tool and responsible for producing a positive but releasable friction union between the spindle and the inserted component.