Wire mesh rivet

Abstract

A wire mesh rivet ( 13 ) is provided which is used to produce a wire mesh isolator ( 11 ) in a bore ( 9 ) of a substrate such as a heat shield ( 7 ) for a vehicle exhaust system. The rivet ( 13 ) comprises a unitary wire mesh structure ( 19 ) which has a collar ( 15 ) and a shank ( 17 ). The collar ( 15 ) has a higher density than the shank ( 17 ), e.g., the collar ( 15 ) has the density of the finished isolator ( 11 ). The rivet ( 13 ) is formed into the finished isolator ( 11 ) by compressing the shank ( 17 ) to form a second collar, while restraining the original collar ( 15 ) from substantially changing its shape. The rivet ( 13 ) can include a metal insert ( 23 ) which prevents the wire mesh of the finished isolator ( 11 ) from experiencing high levels of compression when the substrate is fastened to its supporting structure. The rivets ( 13 ) can be carried by a dispensing strip ( 31 ) and can be formed into the finished isolator ( 11 ) using forming equipment ( 39 ) whose dimensions are compatible with the limited space available with some substrates.

What is claimed is: 
     
         1 . A method for converting a wire mesh rivet into a wire mesh isolator for a heat shield, wherein:
 the heat shield comprises:
 (i) a bore; and 
 (ii) at the location of the bore, a concave side (referred to as the heat shield's concave side) and a convex side (referred to as the heat shield's convex side); and 
   the wire mesh rivet comprises:
 (i) a shank at one end; and 
 (ii) a collar at the other end; 
   
       said method comprising:
 (I) inserting the shank of the wire mesh rivet into the bore of the heat shield with the collar of the wire mesh rivet on the heat shield's concave side; 
 (II) forming the shank of the wire mesh rivet into a second collar on the heat shield's convex side using:
 (a) a forming assembly that compresses the shank to form the second collar; and 
 (b) a positioning assembly that locates the wire mesh rivet in the bore and holds it in place, but does not compress the shank; 
 
 
       wherein:
 (i) the wire mesh rivet is a unitary wire mesh structure; 
 (ii) the average density of the wire mesh rivet's collar is greater than the average density of its shank; and 
 (iii) during step (II), the positioning assembly is on the heat shield's concave side and the forming assembly is on the heat shield's convex side. 
 
     
     
         2 . The method of  claim 1  wherein the heat shield's concave side has limited space available for installing a wire mesh isolator compared to the space available on the heat shield's convex side. 
     
     
         3 . The method of  claim 1  where the bore is located near the top of a raised section of the heat shield. 
     
     
         4 . The method of  claim 1  wherein as seen from the heat shield, the footprint of the positioning assembly is smaller than the footprint of the forming assembly. 
     
     
         5 . The method of  claim 1  wherein the positioning assembly comprises a sleeve which comprises a recess for receiving the collar of the wire mesh rivet, said sleeve having an outer surface whose maximum diameter at the location of the recess is OD sleeve , said maximum diameter satisfying the relationship:
   OD sleeve /OD collar ≤1.1,
 
 where OD collar  is the outside diameter of the collar. 
 
     
     
         6 . The method of  claim 1  wherein the positioning assembly removes the wire mesh rivet from a dispensing strip. 
     
     
         7 . The method of  claim 6  wherein the dispensing strip comprises a plurality of apertures sized to retain the wire mesh rivet's shank and to allow the wire mesh rivet's collar to be pushed through the aperture, each aperture comprising a plurality of circumferential flexible fingers formed by slits in the strip. 
     
     
         8 . The method of  claim 1  wherein the positioning assembly maintains the shape of the wire mesh rivet's collar as the second collar is formed by the forming assembly. 
     
     
         9 . The method of  claim 1  wherein the second collar has a density substantially equal to density of the wire mesh rivet's collar. 
     
     
         10 . The method of  claim 1  wherein the ratio of the average density of the wire mesh rivet's collar to the average density of the wire mesh rivet's shank is the range of 1:2 to 1:3. 
     
     
         11 . The method of  claim 1  wherein when expressed in percent and prior to the conversion of the wire mesh rivet into a wire mesh isolator, the volume ratio D collar  of the wire material in the wire mesh rivet's collar to the overall volume of the collar is in the range of 15% to 25% and the volume ratio D shank  of the wire material in the wire mesh rivet's shank to the overall volume of the shank is in the range of 7.5% to 12.5%, where the volume ratios D collar  and D shank  are calculated from the following equations:
     D   collar =100×( W   collar /( V   collar ×ρ)), and
 
     D   shank =100×( W   shank /( V   shank ×ρ)),
 
 wherein
 D collar  represents the volume ratio of the wire material in the collar to the overall volume of the collar (in percent), 
 W collar  represents the weight of the wire mesh rivet's collar, 
 V collar  represents the volume of the wire mesh rivet's collar, 
 D shank  represents the volume ratio of the wire material in the shank to the overall volume of the shank (in percent), 
 W shank  represents the weight of the shank, 
 V shank  represent the volume of the shank, and 
 ρ represents the density of the wire making up the unitary wire mesh structure (weight/volume). 
 
 
     
     
         12 . The method of  claim 1  wherein the wire mesh rivet has a central bore and comprises a metal insert at least a part of which is within the central bore, wherein the metal insert comprises a wall which has an exterior surface and the exterior surface comprises at least two apertures for engaging the wire mesh of the central bore. 
     
     
         13 . Apparatus for converting a wire mesh rivet into a wire mesh isolator for a heat shield, wherein:
 the heat shield comprises:
 (i) a bore; and 
 (ii) at the location of the bore, a concave side (referred to as the heat shield's concave side) and a convex side (referred to as the heat shield's convex side); and 
   the wire mesh rivet comprises:
 (i) a shank at one end; and 
 (ii) a collar at the other end, the average density of the collar being greater than the average density of the shank; 
   
       said apparatus comprising:
 (I) a positioning assembly adapted to be located on the heat shield's concave side for inserting the shank of the wire mesh rivet into the bore with the collar of the wire mesh rivet on the heat shield's concave side; and 
 (II) a forming assembly adapted to be located on the heat shield's convex side for forming the shank of the wire mesh rivet into a second collar on the heat shield's convex side. 
 
     
     
         14 . The apparatus of  claim 13  wherein the positioning assembly is adapted to hold the wire mesh rivet in place without compressing the shank. 
     
     
         15 . The apparatus of  claim 13  wherein the positioning assembly is adapted to maintain the shape of the wire mesh rivet's collar as the second collar is formed by the forming assembly. 
     
     
         16 . The apparatus of  claim 13  wherein the positioning assembly comprises a sleeve which comprises a recess for receiving the collar of the wire mesh rivet, said sleeve having an outer surface whose maximum diameter at the location of the recess is OD sleeve , said maximum diameter satisfying the relationship:
   OD sleeve /OD collar ≤1.1,
 
 where OD collar  is the outside diameter of the collar. 
 
     
     
         17 . The apparatus of  claim 13  wherein the positioning assembly is adapted to remove wire mesh rivets from a dispensing strip. 
     
     
         18 . Apparatus for converting a wire mesh rivet into a wire mesh isolator for a heat shield, wherein:
 the heat shield comprises:
 (i) a bore; and 
 (ii) at the location of the bore, a concave side (referred to as the heat shield's concave side) and a convex side (referred to as the heat shield's convex side); and 
   the wire mesh rivet comprises:
 (i) a shank at one end; and 
 (ii) a collar at the other end, the average density of the collar being greater than the average density of the shank; 
   said apparatus comprising a positioning assembly adapted to be located on the heat shield's concave side for inserting the shank of the wire mesh rivet into the bore with the collar of the wire mesh rivet on the heat shield's concave side, said positioning assembly comprising a sleeve which comprises a recess for receiving the collar of the wire mesh rivet, said sleeve having an outer surface whose maximum diameter at the location of the recess is OD sleeve , said maximum diameter satisfying the relationship:
   OD sleeve /OD collar ≤1.1,
 
   
       where OD collar  is the outside diameter of the collar. 
     
     
         19 . The apparatus of  claim 18  wherein the positioning assembly is adapted to hold the wire mesh rivet in place without compressing the shank. 
     
     
         20 . The apparatus of  claim 18  wherein the positioning assembly is adapted to maintain the shape of the wire mesh rivet's collar as the shank is formed into a second collar.