<?php 

$acc = explode( ',',

    'À,Á,Â,Ã,Ä,Å,à,á,â,ã,ä,å,Ò,Ó,Ô,Õ,Ö,Ø,ò,ó,ô,õ,ö,ø,È,É,Ê,Ë,é,è,ê,ë,Ç,ç,Ì,Í,Î,Ï,ì,í,î,ï,Ù,Ú,Û,Ü,ù,ú,û,ü,ÿ,Ñ,ñ' );

$no_acc = explode( ',',

    'A,A,A,A,A,A,a,a,a,a,a,a,O,O,O,O,O,O,o,o,o,o,o,o,E,E,E,E,e,e,e,e,C,c,I,I,I,I,i,i,i,i,U,U,U,U,u,u,u,u,y,N,n' );



$chaine = str_replace( $acc, $no_acc, $chaine );

$chaine = ereg_replace( '[^a-zA-Z0-9]', '_', $chaine );

$chaine = ereg_replace( '-+', '-', $chaine );

$chaine = ereg_replace( '^-+', '', $chaine );

$chaine = ereg_replace( '-+$', '', $chaine );