Method of lining cylindrical bores

A method of lining a cylindrical bore, which method comprises the steps of:

• (a) providing a block having a cylindrical bore;
• (b) selecting a strip of lining material having free ends and of such a length that when said strip is formed into a cylindrical liner for said cylindrical bore and then pressed into said cylindrical bore, said formed strip is subjected to hoop-stress;
• (c) providing a jig-plate defining a groove of arcuate cross-section with a radius of curvature substantially equal to that of the unlined bore and a co-operable mandrel which has an at least partially circular cross-section the diameter of which is substantially equal to that of the lined bore;
• (d) positioning said strip of lining material in said jig-plate and employing said jig-plate to press said selected strip into said groove;
• (e) retaining the partially-formed strip in the groove of the jig-plate and employing jig cheek-pieces each of which defines a part-circular groove of substantially the same radius of curvature as the groove in the jig-plate further to deform said strip by moving said jig cheek-pieces with respect to said jig-plate to a position in which said cheek-piece grooves and said jig-plate groove together define a cylinder of substantially the same diameter as that of the unlined bore, thereby enclosing and deforming said strip with said free ends abutting one another to form a cylindrical liner which is subjected to hoop-stress within the jig;
• and
• (f) pressing the thus-formed liner out of the jig into the cylindrical bore whilst maintaining the hoop-stress within said liner thereby forming a lined block.