Tools – Wrench – screwdriver – or driver therefor – Rigid jaws
Reexamination Certificate
2000-05-08
2001-07-24
Smith, James G. (Department: 3723)
Tools
Wrench, screwdriver, or driver therefor
Rigid jaws
C081S186000
Reexamination Certificate
active
06263769
ABSTRACT:
REFERENCES TO RELATED APPLICATIONS
This application relates to U.S. patent application entitled WRENCH WITH PINCH-LOCKING ENGAGING SURFACES, filed by the inventor herein, of which the application serial number and filing date are not known at the time of this filing.
FIELD OF THE INVENTION
The present invention relates to hand tools, particularly wrenches and most particularly open end type wrenches.
BACKGROUND OF THE INVENTION
An open end wrench is a wrench that has an open ended wrench head used to turn and control the rotation of bolts, nuts and various fasteners. Examples of open end wrenches include, but are not limited to, double open end, combination, flare nut, flex head etc. An open end wrench can access fasteners under certain limited-access conditions where a closed end or box wrench cannot, however, an open end wrench is much weaker by design than a box wrench. The weakness is associated with the inevitable jaw spread produced by the cam effect of fastener to wrench, under torque. This inherent weakness reduces torque capacity and promotes fastener deformation and wrench wear.
Subsequently, there have been numerous attempts to increase the strength and torque capacity of open end wrenches. The use of sharp teeth or serrations has been relatively effective on all but extremely hard fasteners, however, this technology sacrificed the fastener to gain additional torque by leaving bite or shred marks on the fastener. The use of inclined and arcuate driving surfaces has been effective at reducing the bite marks and fastener deformation, however, this technology has been generally less effective at increasing wrench strength and torque capacity. In addition, most prior attempts to improve the torque capacity of open end wrenches have consequently produced an increase in the total free play arc between wrench and fastener which applicant believes to be objectionable to most users.
SUMMARY OF THE INVENTION
The present invention involves a high torque, open end wrench head which when turned in either direction can provide a substantial increase in torque capacity while reducing fastener deformation and wrench wear.
The present invention more specifically involves a wrench head that has an open end for a fastener which has at least two substantially parallel outer engaging surfaces that create an across-width dimension. The wrench head has an orifice which comprises six principle internal engaging surfaces each being substantially flat and positioned around an imaginary central axis. The first, second and third internal engaging surfaces are positioned on a first jaw, and the fourth, fifth and sixth internal engaging surfaces are positioned on a second opposing jaw. The first internal engaging surface is positioned closer to the open end than the second internal engaging surface and diverges outward from the imaginary central axis. The second internal engaging surface is positioned closer to the open end than the third internal engaging surface and is substantially parallel to the imaginary central axis. The third internal engaging surface diverges outward from the imaginary central axis. The fourth internal engaging surface is positioned crosswise opposing the first internal engaging surface and diverges outward from the imaginary central axis. The fifth internal engaging surface is positioned crosswise opposing the second internal engaging surface and is substantially parallel to the imaginary central axis. The sixth internal engaging surface is positioned crosswise opposing the third internal engaging surface and diverges outward from the imaginary central axis. The second and fifth internal engaging surfaces are spaced apart by a dimension slightly greater than the across-width dimension of the fastener. The first and sixth internal engaging surfaces are spaced apart by a dimension slightly less than the across-width dimension of the fastener and the third and forth internal engaging surfaces are spaced apart by a dimension slightly less than the across-width dimension of the fastener.
The present invention has been developed recognizing the inevitable jaw spread of a standard open end wrench under torque and the subsequent need to increase wrench strength and torque while reducing fastener deformation and wrench wear. The present invention wrench, therefore, relies upon a predetermined amount of jaw spread to develop a “pinch locking” effect and substantial surface-to-surface engagement with a fastener during the torque process. In addition, the present invention has been developed recognizing the need to achieve such increases in performance without significantly increasing the total free play arc between wrench and fastener or precluding wrench head offset (“flip-flop”) capability.
Accordingly, it is an important objective of the present invention described above to significantly increase the strength and torque capacity of an open end wrench head without sacrificing the fastener by leaving bite marks, shred marks or otherwise deforming the fastener.
It is another objective of the present invention to achieve the improved performance without significantly increasing the total free play arc between wrench and fastener and while maintaining the ability to flip the wrench over or “flip-flop” the wrench in limited access situations.
It is another objective of the present invention that it be commercially viable, simple in design, and cost efficient to manufacture.
REFERENCES:
patent: 4776244 (1988-10-01), Olson et al.
patent: 5284073 (1994-02-01), Wright et al.
patent: 5878636 (1999-03-01), Baker
patent: 6082228 (2000-07-01), Macor
Proprietary Technologies, Inc.
Smith James G.
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