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Metal eyeglass frame

A pair of eyeglasses generally comprises an eyeglass frame and two eyeglass lenses affixed to the eyeglass frame. The frame of eyeglasses or spectacles typically consists of a front rim which is formed to hold a lens for each eye and of two temple arms which are attached to the two outer sides of the rim. Each temple arm is long enough so that, when the front rim is positioned with the lenses in front of the eyes, the temple arm will rest on top of the ear where the ear meets the head. Generally, an eyeglass frame is made of metal or plastic material and is made into one piece. A metal eyeglass frame generally includes a pair of rims each holding a lens, an upper and a lower bridge for connecting the rims, a pair of lugs or decorations projecting sideways from the associated rims, a pair of pads or cringles attached to the facing edges of the rims below the bridges, and a pair of bows or sides extending rearwardly from the associated lugs. The pads are made of synthetic resin and adapted to rest on the nose of the wearer in order to hold the eyeglasses in position on the wearers face. The metals which have historically been used to make metal eyeglass frames have usually been chosen in large part for their ease of fabrication. Metals such as nickel-silver, monel, and phosphor bronze have fairly high yield strength but quite low work-hardening which allows them to accept large deformations during manufacture. Pure titanium or some nickel-titanium base alloys also have been made use of as said eyeglass parts because they are excellent in their properties such as mechanical strength, corrosion resistance, spring property or resilience and are lighter in their weight. In particular, Ni-Ti alloys are very useful in this field owing to their super elasticity which enhances to them the so-called "shape memory" property depending upon their compositions.

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