| 摘要 |
A plastic bridge for supporting spectacle lenses fitted with a metal rim is made from a preformed 'U' section channel, having a mouth narrower than the width of the metal rim, by machining a shallow groove on the inner face of each wall of the plastic channel to accept the edges of the metal rim as a snap fit. Plain channel walls require less complex moulding or forming equipment than profiles with undercut surfaces. Alternative grooves can be machined in similar channel profiles, by using alternative milling cutter profiles, to suit different lens rim profiles. |
