Fastening arrangement for plastic to metal parts

• US 4,973,102 A
• Filed: 11/16/1989
• Issued: 11/27/1990
• Est. Priority Date: 11/16/1989
• Status: Expired due to Fees

• Current Assignee: Chrysler Corporation (Stellantis NV)
• Original Assignee: Chrysler Corporation (Stellantis NV)
• Inventors: Bien, Alfred A.
• Primary Examiner(s): Pedder, Dennis H.
• Application Number:
  US07/437,248
• Time in Patent Office: 376 Days
• Field of Search: 296/187, 296/191, 296/901, 296/198, 411/43, 411/338, 411/339, 411/368, 411/369, 411/544
• US Class Current: 296/187.01
• CPC Class Codes: B62D 29/048 Connections therefor, e.g. joints B62D29/045 takes precedence
• CPC Class Codes: F16B 19/04 Rivets; Spigots or the like fastened by riveting lead seals G09F3/00
• CPC Class Codes: F16B 19/1054 the pull-mandrel or the like being frangible
• CPC Class Codes: F16B 2200/97 having differing thermal expansion coefficients
• CPC Class Codes: F16B 43/00 Washers or equivalent devices; Other devices for supporting bolt-heads or nuts circlips F16B21/18; for indicating tensile load F16B31/02; forming a whole with the bolt or nut F16B33/00; locking bolts or nuts by means of a fixed plate or ring, or washer-like resilient plates F16B39/10, F16B39/24
• CPC Class Codes: F16B 5/04 by means of riveting rivets F16B19/04

Abstract

The present invention relates to an improved arrangement for attaching a plastic panel and metal mounting strip sub-assembly to an automotive body metal substructure enabling controlled distortion free thermal expansion and contraction of the plastic panel relative to the mounting strip. The attaching arrangement comprises a metal spacing washer having a tubular sleeve portion formed with an integral frusto-conical spring flange. The washer sleeve portion free end extends through an elongated slot in the mounting strip and an aligned circular opening in the panel. A blind breakstem rivet is inserted through the washer bore and upon being set applies a predetermined axial clamping force biasing the washer flange into contact with the mounting strip. The rivet head undersurface may be provided with an annular locking ring adapted to engage the plastic panel out surface. Upon the panel being heated to its thermal-relaxation temperature the locking ring is embedded in the softened plastic panel thereby reducing excess load on the washer spring flange in a tolerance self-compensating manner.

Claims

1. In an automobile vehicle body having a metal substructure, a one-piece plastic panel having an integral planar flange having outer and inner planar surfaces, said flange having its inner surface in flush contact with an inner planar surface of said substructure with the plastic flange having different thermal expansion characteristics than the metal substructure, and fastening means for securing the plastic panel flange to the substructure comprising:

a fastening arrangement including a spring washer having a tubular sleeve portion defining an axial through bore of predetermined axial extent and an integral frusto-conical spring flange extending radially outwardly at one end thereof, said sleeve portion other end extending through an elongated slot in said substructure and a circular hole of predetermined diameter in said plastic flange;

said washer tubular sleeve portion having a predetermined axial extent such that with the periphery of said washer spring flange contacting the outer planar surface of said substructure and with said tubular sleeve portion other end substantially flush with the outer surface of said plastic flange;

a blind break-stem rivet comprising an elongated tubular rivet body having a head at one end and an integral elongate shank, said shank being adapted upon setting of said rivet to expand radially to form a blind end, an axial bore extending throughout said head and said shank, and a mandrel disposed in said axial bore, said mandrel having an elongate stem which projects from the head end of said axial bore, a plug, and a breakneck portion joining said stem and said plug;

PG,17

said washer through bore having a predetermined diameter telescopically receiving said rivet elongated shank therethrough such that the undersurface of said head contacts the outer surface of said plastic flange;

whereby upon said rivet being set causing radial expansion of the shank to form a blind head when the mandrel is pulled to move the plug relatively towards the head end of said body, wherein a predetermined axial clamping force is applied to said washer causing said washer radial spring flange to resiliently bias said head undersurface into contact with said plastic flange outer surface providing heat induced sliding movement of said plastic panel relative to said metal substructure.

2. In an automobile vehicle body having a metal substructure, a plastic panel for attachment to said substructure, fastening means fixedly attaching the panel to said substructure such that said plastic panel is slidable relative to said substructure, the improvement in said fastening means wherein:

said plastic panel having inner and outer planar surfaces, at least one hole of predetermined diameter formed in said panel;

said metal substructure having a planer portion defining inner and outer planer faces, said plastic panel inner surface in flush contact with said substructure planer portion inner face such that said one hole is aligned with an elongated slot in said substructure;

a spring washer including a tubular sleeve portion defining an axial through bore of predetermined axial extent, an integral frusto-conical spring flange extending radially outwardly at one end of said sleeve portion, said sleeve portion other end extending through said substructure elongated slot and said plastic panel hole, said sleeve portion having a predetermined axial extent such that with the peripheral edge of said washer spring flange contacting said substructure outer face said washer sleeve portion other end is substantially flush with said plastic panel outer surface;

a blind break-stem rivet having an elongated tubular rivet body formed with a rivet head at one end and an integral elongate shank, said rivet head having its undersurface formed with a thread-like concentric ring of a predetermined diameter terminating in an annular sharp crest extending a predetermined axial distance towards said shank;

said rivet body shank being adapted to expand radially to form a blind end, an axial bore throughout said rivet head and shank, and a mandrel disposed in said body bore, said mandrel having an elongate stem which projects from the rivet head end of said body bore, a plug, and a breakneck joining said stem and said plug;

said washer through bore having a predetermined diameter telescopically receiving said rivet elongated shank therethrough such that said rivet head undersurface annular sharp crest initially contacts said plastic panel outer surface in a line contact manner;

whereby upon said rivet being set causing radial expansion of said shank to form a blind head when said mandrel is pulled to move said plug relatively towards said rivet head end of said body, wherein an axial clamping action is applied to said washer causing said washer radial spring flange to bias said rivet head annular sharp crest into pressure contact against said plastic panel outer surface; and

wherein upon said attached plastic panel being heated to its thermal-relaxation temperature said plastic panel softens such that said annular sharp crest penetrates said plastic panel outer surface to a depth sufficient to relieve excess preloading of said spring flange providing a controlled sliding resistance of said washer spring flange with said metal substructure such that said plastic panel is slidable relative to said substructure upon thermal growth of said plastic panel.

3. The improved fastening means as set forth in claim 2 wherein said thermal relaxation temperature is in the range of 250°

F. to 350°

F.