FR2871861A1 - Sealed rivet especially for fastening thin material has supple seal adhering to rivet and avoiding any need for previous or subsequent operation - Google Patents

Abstract

The rivet, comprising a cylindrical shank (f) with a head (t) projecting radially from its outer lateral wall, has a supple seal (j) fixed under the head and forming part of the rivet's structure, adhering to the head and/or shank. Before the seal is applied the rivet is prepared by chemical or mechanical means, or by applying an adhesive varnish. The seal can cover a portion of the shank over a length (d2) up to five times the size (d1) of the covered portion of the head, and its outer surface can be either convex or concave.

Description

2871861 -1-

  The present invention relates to liquid or gastight rivets, particularly those which serve as drowned nuts that can be installed when only one side of the support to be riveted is accessible.

  It also relates to a rivet sealing process that can be operated in a wide temperature range or on a support having significant geometrical defects. The method is suitable for implementing the rivet according to the invention.

  In this field, we already know rivets for a certain tightness. We distinguish several methods to achieve this seal: - use of seal or sleeve reported to the rivet, illustrated by the patent EP 0 589 144 Al; use of a solder, an adhesive, a putty or a silicone applied before or after the riveting operation, the solidification or polymerization of the additive ending thereafter, illustrated by the patent No. 1,275,536 A1; use of a soft metal crush on a harder metal, illustrated by WO9429602; - Use of plastic rivet, illustrated by the patent No. 95 01669.

  These various methods are not completely satisfactory.

  Indeed, the addition of a preformed element and not secured to the rivet makes the riveting operation difficult to mechanize. It also requires geometric adaptations on the associated rivets to prevent creep of the seal once compressed, resulting in additional cost.

  The application of a sealing product requires an additional operation more or less important, prior to use, resulting in very poor productivity.

  Seals made by compressing one metal against another or crushing a plastic rivet are rendered defective by the repetition of even small temperature variations and hardly compensate for surface defects of the support, resulting in a significant restriction of application domain.

  The present invention aims to overcome the disadvantages of current and present devices, thanks to a very advantageous rivet design.

  First of all, the invention overcomes the prejudice that the outer periphery of the rivet shaft (f) should be ensured by the crushing of the material constituting the barrel (f) of the rivet. or by an outer element reported. Indeed, the joints or sleeves are eventually delivered mounted on the rivet but are never part of the actual structure of the rivet. On the contrary, the invention proposes to use an elastomeric material applied, shaped and polymerized on the rivet so that it becomes an inseparable structural element. With this method, the user of these rivets is released from any operation before or after riveting to achieve the desired seal on the outer periphery of the barrel (f) of the rivet.

  The advantages of the invention are numerous, particularly as regards the speed of implementation, the mechanization, the versatility of use and the sealing performed on the periphery of the rivet obtained over a wide temperature spectrum.

  The crushing of the rivet causes compression of the joint (j) integrated which fills the geometrical defects of the support (s) to form a rivet impervious to liquids or gases. The potential mechanical games are caught by the seal (j), especially for small thicknesses of the support (s). The support (s) may consist of one or more thicknesses of materials.

  The present invention relates to a tapped or smooth tubular rivet, blind or opening, comprising a barrel (f) cylindrical and extended by a head (t) projecting radially from the outer side wall of the barrel (f), and a seal (j) flexible seal fixed under the head (t), which has the same axis as the barrel (f). This seal (j) adheres exclusively to the head (t) or the barrel (f) of the rivet.

  The seal (j) is formed of an elastomer such as a silicone, a polyurethane or a rubber deposited in the uncured state under the head (t) of the rivet. The polymerization operation is completed before the use of said rivet.

  The surface of the rivet can be pretreated to increase the adhesion of the seal (j). Thus chemical or mechanical attacks or the application of a tack coat or any other method for improving the attachment can be used.

  The seal (j) circumferentially covers the lengths (d1) and (d2); (dl) totally or partially covering the underside of the head (t), (d2) from the head (t) towards the end of the barrel (f) over a length of 0 to 5 times the length (dl).

  The profile of the joint (j) connecting its two opposite edges can go from convex to concave.

  2871861 -3- Thus, the seal (j) fills the space between the head (t) and the support (s), and can go as close as the hole made in the support (s). This performance makes it possible to fill irregular holes or that would not be adjusted to the diameter of the barrel (f) of the rivet.

  The seal (j) is flexible and elastic, to fill the geometric defects of the support (s), such as scratches, sheers, irregular perforation, and compensate for differential expansion between rivet and support (s).

  The visualization of the creep of the seal (j) under the head is facilitated by the contrasting hue of the seal (j) with respect to the head (t); this makes it possible to check the integrity of the joint (j): homogeneous creep, absence of cutoff, etc.

  Thus, the creep of the seal (j) serves as a visual indicator during the removal or control witness over time.

  The present invention is directed to blind or through rivets, having an inner wall of the barrel (f) threaded or smooth.

  Figure 1 shows the device of the invention.

  Figure 2 shows, in section, a variant of this device.

  The invention may be in the various embodiments set out below: the sealing substance is silicone; the sealing substance has a sufficient adhesion so as not to peel off under the compression force; - The sealing substance will preferably cover the entire lower surface of the head (t) and a portion of the barrel (f); the sealing substance retains its elastic properties over a wide temperature range.

  The invention also relates to a method of depositing a seal (j) on a grafted tubular rivet characterized in that it consists in: - performing a possible pretreatment of the rivet surface to improve the gripping performance of the elastomer; - Spraying, buffering or any other suitable method, the uncured elastomer in the selected areas; to activate the polymerization of the elastomer.

2871861 -4-

Claims (10)

  1. Watertight rivet intended to be fixed in particular on a thin support, comprising a barrel (f) cylindrical and extended by a head (t) projecting radially from the outer side wall of the barrel (f), and a seal (j) d flexible seal fixed under the head (t) which has the same axis as said barrel (f), characterized in that said seal (j) is part of the very structure of the rivet constituting an inseparable structural element and is such that adheres exclusively to the rivet, the head (t) and / or the barrel (f) of said rivet, so that the desired seal on the outer periphery of the barrel (f) of the rivet after riveting is released from any previous or subsequent operation .   2. Rivet according to claim 1, characterized in that the seal (j) is formed of an elastomer such as a silicone, a polyurethane or a rubber deposited in the uncured state under the head (t) of the rivet , the polymerization operation being completed before the use of said rivet.   3. rivet according to claims 1 or 2, characterized in that it comprises various pre-treatment operations on the rivet allowing increased adhesion of the seal (j) on the rivet, such as, chemical or mechanical attacks or application of a nail varnish.   4. Rivet according to any one of the preceding claims, characterized in that the seal (j) circumferentially covers the lengths (dl) and (d2); (dl) totally or partially covering the underside of the head (t), (d2) from the head (t) towards the end of the barrel (f) over a length of 0 to 5 times the length (dl).   5. Rivet according to any one of the preceding claims, characterized in that the profile of the joint (j) connecting its two opposite edges can go from convex to concave.   6. Rivet according to any one of the preceding claims, characterized in that the seal (j) is flexible and elastic type, to fill the geometric defects of the support (s), such as scratches, sheers, irregular perforation, and to compensate for the differential dilations between rivet and support (s).   2871861 -5- 7. Rivet according to any one of the preceding claims, characterized in that, the contrasting shade of the seal (j) relative to the head (t) improves the visualization of the integrity of the seal (j).   8. Rivet according to any one of the preceding claims, characterized in that it is applicable to the realization of rivets with inner wall drum (f) threaded or smooth.   9. Rivet according to any one of the preceding claims, characterized in that it is applicable to the realization of rivets with barrel (f) blind or opening.   10. A method of making the rivet according to any one of the preceding claims, characterized in that the implementation of the seal (j) consists of the removal of a non-polymerized elastomer on a surface optionally pretreated rivet and in the activating the polymerization of the elastomer, thereby forming said seal (j).