Method of manufacture for a plastic-capped panel fastener
View Patent ↗A captive panel fastener is manufactured by first overmolding a plastic cap around the head of a screw, the cap having a cylindrical plastic skirt extending downwardly beyond the base of the screw head and formed with a circular opening at the bottom. After a compression spring is placed around the shank of the screw, the screw is pressed against a top surface of a ferrule to a point where the capped-skirt extends downwardly below a ferrule flange. At that point, heat and pressure are applied radially inwardly around the periphery of the plastic skirt along its bottom edge until it is permanently deformed to a point where the bottom of the skirt is smaller in diameter than the ferrule flange. The screw is thereby captivated to the ferrule between extended and retracted positions.
1. A method of manufacturing a captive panel fastener comprising the steps of:
providing a plastic-capped screw having a screw head, a shank and a cylindrical plastic skirt of the cap extending downwardly beyond a base of the screw head, said skirt having a circular opening at the bottom;
placing a compression spring around the shank of said screw;
inserting said capped screw into a throughbore of a ferrule having a radially extending flange at a top end and panel attachment means at a bottom end thereof;
pressing the base of said screw head against a top surface of said ferrule where said skirt extends downwardly below said ferrule flange; and
applying heat and pressure radially inwardly around a periphery of said plastic skirt along a bottom edge thereof such that said bottom edge is permanently deformed to a point where the opening at the bottom of said skirt is reduced to a radiused ring of lesser diameter than the outer diameter of said ferrule flange thereby axially captivating said screw to said ferrule between retracted and extended positions of the screw.
2. The method of claim 1 wherein said plastic cap is formed around said screw head by over-molding.
3. The method of claim 2 wherein said pressure is applied by rolling contact against a heated forming surface.
4. The method of claim 3 wherein said screw is composed of metal.
5. The method of claim 4 wherein said shank is elongate and threaded.
6. A method of manufacturing a captive panel fastener comprising the steps of:
over-molding a plastic cap around the head of a screw having a shank, the cap having a cylindrical plastic skirt extending downwardly beyond a base of the screw head, said skirt having a circular opening at the bottom;
placing a compression spring around the shank of said screw;
inserting said capped screw into a throughbore of a ferrule having a radially extending flange at a top end and panel attachment means at a bottom end thereof;
pressing the base of said screw head against a top surface of said ferrule where said skirt extends downwardly below said ferrule flange; and
applying heat and pressure radially inwardly around a periphery of said plastic skirt along a bottom edge thereof such that said bottom edge is permanently deformed to a point where the opening at the bottom of said skirt is reduced to a radiused ring of lesser diameter than the outer diameter of said ferrule flange thereby axially captivating said screw to said ferrule between retracted and extended positions of the screw.
7. The method of claim 6 further described in that said skirt has a circular opening at its bottom end.