To fix a screw in a cylindrical surface without any play without any special hole machining necessary in the cylindrical surface by providing a washer hole, forming a contact surface to be a recessed cylindrical shape roughly matched with the cylindri cal surface and a counter bored hole to be a recessed part matching the bearing surface shape of the screw.
The edge part 3 of a washer is contacted with one hole end. For the washer, a screw hole 1 having a diameter of 11 mm is provided in its center, a wall body 4 conical by 90° from the edge part of this hole is formed as a counter bored hole 2, and this wall body is bent roughly vertically roughly in its center to be used as an edge part 5. The end part 3 of this edge part 5 is formed as a cylindrical envelope having a side viewed curvature radius of about 38 mm. The end part 3 of the washer is preferably formed to have a shape identical to the cylindrical curvature radius, but since it is deformed to match the cylindrical surface when it is strongly fastened to the cylindrical surface even if there is a slight difference in curvature radius, no problems exist. For the counter bored hole 2 of this washer, the bearing surface B1 of the heat part of a flat countersunk head screw B is contacted, and the tip part of the flat countersunk head screw B is threadedly attached with a metal fitting.
DEKI NOBUHISA
INAGAKI YOUHEI
