Assembly For and Method of Affixing a Fastener to a Panel
Attachment of a rectangular clinch fastener is achieved with the panel receiving hole side-gaps at least partially closed by features incorporated into the installation tooling. Panel displacement features are added to the face of the installation anvil tool to draw from the panel material and move this material inwardly up against the side face of the fastener thus greatly closing the receiving hole side gaps. The anvil features include two raised displacer protrusions extending above the pressing surface of the anvil aligned with the non-clinching side edges of a rectangular tool well. The anvil features have a trapezoidal shape with a slanted face facing inwardly such that upon installation the panel is deformed to close or greatly reduce the length of the unwanted side edge gaps.
1 . A method of attaching a fastener having a rectangular base to a panel having a rectangular receiving hole, comprising the steps of:
placing a panel with a rectangular receiving hole having a length and a width against a top of an anvil having a pressing surface with upward extending projections in alignment with said hole, said anvil further having a well extending downward from directly below said panel hole;
placing a fastener with a rectangular base through the panel receiving hole against a top of the panel and partially into the anvil well, said base having two pairs of parallel opposing sides, a first pair of opposing longitudinal sides having undercuts for receiving the cold flow of material from the panel defining a length of said base and a second pair of opposing lateral sides being planar and featureless and defining a width of said base, the width of said base being less than the receiving hole width such that gaps in the hole exist between the lateral pair of sides of said base and the panel; and
pressing said fastener against the panel and the anvil whereby said projections on the anvil pressing surface displace material of said panel inwardly into said gaps and against the second pair of fastener side edges such that medial portions of said gaps are fully closed while simultaneously material of the panel is forced into said undercuts attaching the fastener to the panel.
2 . The method of claim 1 wherein said projections extend upwardly from the sides of the anvil bore.
3 . The method of claim 2 wherein the projections have a trapezoidal profile with a front surface facing toward the anvil well and a rear surface facing away from the well, said rear surface extending vertically while the front surface is angled upwardly and away from the bore.
4 . The method of claim 3 wherein the front surface extends upwardly at an angle of approximately forty-five degrees from an intersection with the anvil pressing surface.
5 . The method of claim 4 wherein the undercuts extend horizontally through the longitudinal sides of the fastener base.
6 . The method of claim 5 wherein the base of the fastener lies flush with a top surface of the panel after pressing.
7 . An assembly of a fastener affixed to a panel, comprising:
a panel having a rectangular receiving hole with a length and a width:
a fastener with a rectangular base extending through the receiving hole, said base having two pairs of parallel opposing sides, a first pair of longitudinal sides having undercuts receiving the cold flow of material from the panel and a second pair of lateral featureless planar sides; and
gaps between the lateral sides and the panel having medial portions fully closed by the deformation of the panel material against the lateral sides of the fastener performed during attachment of the fastener to the panel.
8 . The assembly of claim 7 performed by pressing the fastener and the panel against an anvil having projections on a pressing surface thereof which displace material of the panel inwardly into said gaps.
9 . The assembly of claim 8 wherein the projections have a trapezoidal profile with a front surface facing toward the anvil bore and a rear surface facing away from the bore, said rear surface extending vertically while the front surface is angled upwardly and away from the bore.
10 . The assembly of claim 9 wherein the front surface extends upwardly at an angle of approximately forty-five degrees from an intersection with the anvil pressing surface.