Pivotal hand tool with flexural pivot joint and method of assembling same

A pivotal hand tool comprising:

• first and second lever members respectively having cooperating jaws at adjacent ends thereof, said lever members being disposed in intersecting relationship and respectively having arcuate openings therein aligned along a common axis, first and second cylindrical members respectively coaxially disposed in said openings in axially spaced-apart relationship and respectively fixedly secured to said first and second lever members for movement therewith, a first mounting member discrete from said first cylindrical member and disposed in said opening of said first lever member between said first lever member and said first cylindrical member and fixed to each, a second mounting member discrete from said second cylindrical member and disposed in said opening of said second lever member between said second lever member and said second cylindrical member and fixed to each, and first and second thin flexural leaf spring elements disposed in crossed but non-contacting relationship within said cylindrical members, each of said flexural elements having edge portions respectively fixedly secured to said first and second cylindrical members for interconnecting same.

A method of assembling a pivotal hand tool having first and second lever members respectively having arcuate openings therein and interconnected by a flexural pivot assembly including flexural leaf spring elements each fixed to first and second coaxial and axially spaced-apart cylindrical members, said method comprising the steps of:

• placing a spacer formed of a material having a very low coefficient of friction between the cylindrical members and spaced from the leaf spring elements without exerting substantial axial forces on the cylindrical members thereby to prevent axial movement of the cylindrical members toward each other, disposing the first cylindrical member coaxially in the opening in the first lever member and fixing it to the first lever member, and disposing the second cylindrical member coaxially in the opening of the second lever member and fixing it to the second lever member, whereby the spacer absorbs axial compressive forces applied to the cylindrical members and minimizes transmission thereof to the leaf spring elements,

The method of claim 18, wherein the first mounting member is press-fitted around the first cylindrical member after the spacer is disposed between the cylindrical members, then the first mounting member is press-fitted in the opening of the first lever member, then the second cylindrical member is disposed in the opening of the second lever member, then the second mounting member is press-fitted in the opening of the second lever member between the second lever member and the second cylindrical member.