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(11) | EP 0 369 655 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improved screwdriver bit for Phillips-head fasteners |
| (57) A modified Phillips-type screwdriver bit is disclosed that is fully compatible with
a standard Phillips-head fastener, and is designed to significantly increase the level
of torque that can be applied to the fastener while at the same time substantially
reducing the cam-out forces normally produced by a standard Phillips screwdriver bit.
These results are accomplished by forming generated surfaces along the side walls
of the bit wings so that the included angle defined by the converging side walls of
adjoining bit wings gradually increases from the Phillips standard 92 degrees at the
base of the bit wings to approximately 105 degrees at the wing tips. This configuration
serves to confine the application of torque to the side surfaces of the bit wings
initially along contact lines adjacent and parallel to the roots of the bit wings
with the contact area gradually progressing radially outwardly as torque levels increase
and the opposing side surfaces of the recess wings in the head of the fastener begin
to deform. |