# US 2019/0170177 A1 · Lubricating cap, fastener comprising this type of cap and interference assembly process > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0170177 A1 - Document ID: US20190170177A1 - Status: Published application - Kind: A1 - Application number: 16/324,854 - Filed: 2017-08-11 - Published: 2019-06-06 - Earliest claimed: 2016-08-12 - Assignees: Lisi Aerospace - Applicants: Lisi Aerospace - Inventors: Alexandre Berthou; Martial Broucke - Web page: https://patentgrep.com/patent/US20190170177A1 ## CPC - F16B 19/05: Bolts fastening by swaged-on collars (F16B19/08 takes precedence) - F16B 33/06: Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure {or fretting (corrosion preventing means F16B33/008; settable coatings for locking threaded members F16B39/225; deformable coatings for locking threaded members F16B39/34)} - F16N 1/00: Constructional modifications of parts of machines or apparatus for the purpose of lubrication - F16B: DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING (couplings for transmitting rotation F16D) - F16N: LUBRICATING ## Abstract The object of the invention is a cap to lubricate an inner wall of a perforation going through at least two elements of the structure. The cap comprises a tubular body and at least one lubricant reserve, and before installation in the structure said cap has a largest external diameter larger than an internal diameter (DS) of the perforation, and the cap lubricates the internal surface of the perforation when its largest external diameter is radially compressed by a wall of the perforation. The invention also concerns a fastener comprising this type of cap, and an interference assembly process for the fastener equipped with the cap. The invention is applicable to the assembly of aircraft structures. ## Claims ### Claim 1 A cap to lubricate an internal wall of a perforation or a sleeve with internal diameter (DS) passing through at least two structural elements characterized by the fact that the cap comprises a tubular body and at least one lubricant reserve, before insertion in the perforation or in the sleeve, the cap has a largest external diameter larger than the smallest internal diameter (DS) of said perforation or sleeve, and by the fact that the lubricant of said cap is distributed over an internal surface of the perforation or the sleeve when said cap is inserted into the perforation or the sleeve and is radially compressed by the internal wall of said perforation or sleeve. ### Claim 2 (depends on 1) The cap according to claim 1 in which the tubular body of the cap has at least one wall facing an exterior surface of the tubular body and such that a cavity between the wall and the tubular body forms a reservoir for the lubricant. ### Claim 3 (depends on 2) The cap according to claim 2 in which an exterior surface of the wall of at least one skirt has the largest external diameter of the cap, before insertion into the perforation or the sleeve. ### Claim 4 (depends on 1) The cap according to claim 1 in which the tubular body, within a radial plane of the cap, presents a U-shaped section; this U-shaped section determines a cavity that forms a reservoir for the lubricant; the cap also features an annular piston feature able to slide with clearance into said cavity of the tubular body, and the piston element has at least one skirt with the largest exterior diameter of the cap before insertion. ### Claim 5 (depends on 1) The cap according to claim 1 in which the tubular body, in a radial plane of said cap, has a U-shaped section, which determines a cavity that forms a lubricant reservoir, the cap also comprises an annular piston element which is able to slide into said cavity of the tubular body, and the piston element comprises a skirt with the largest external diameter of the cap before insertion, an external wall of the tubular body, formed by an external branch of the U-section, comprises at least one opening allowing said lubricant to pass through to the outside of said cavity via said light. ### Claim 6 (depends on 1) The cap according to claim 1 in which the tubular body, in a radial plane of said cap, has a U-shaped section, which determines a cavity that forms a lubricant reservoir, the cap also comprises an annular piston element which is able to slide into said cavity of the tubular body, and the piston element comprises a skirt with the largest external diameter of the cap before insertion, an internal wall of the tubular body, formed by an external branch of the U-section, or a wall of an external outline of the piston, comprises at least a channel on said wall and passing through to the outside of the U-shape allowing said lubricant to pass through to the outside of said cavity via said ridge. ### Claim 7 (depends on 1) The cap according to claim 1 comprising at least one circumferential rib on an exterior surface of the tubular body, the rib has the largest external diameter of the cap before insertion; a holding space between the rib and the tubular body, or between several ribs, forming a reservoir for the lubricant. ### Claim 8 (depends on 1) The cap according to claim 1, in which the lubricant is in a pasty state. ### Claim 9 (depends on 8) The cap according to claim 8, in which the lubricant comprises a blend of cetyl alcohol and fats. ### Claim 10 (depends on 8) The cap according to claim 8 in which the lubricant is covered with a solid envelope designed to self-destruct when the fastener is inserted into the perforation to release the lubricant. ### Claim 11 (depends on 1) A fastener to assemble at least two structural elements comprising a perforation, the fastener having an enlarged head and a smooth shaft with, before installation, an external diameter (D1) larger than an internal diameter (DS) of the perforation or the sleeve inserted into said perforation, characterized by the fact that said fastener comprises a cap according to claim 1, positioned on said fastener opposite the enlarged head of one distal end of the smooth shaft. ### Claim 12 (depends on 11) The fastener according to claim 11 such that the distal end of the fastener has a recess and such that the cap also has a protruding holding element matching said recess. ### Claim 13 (depends on 11) The fastener according to claim 11 such that the distal end of the fastener features traction grooves or a threading, and such that the tubular body of the cap is placed on said grooves or threading. ### Claim 14 (depends on 1) A process for assembling at least two structural elements comprising a perforation; the process involves the following steps: assembling a cap according to claim 1 on a fastener featuring an enlarged head and a smooth shaft with, before installation, an external diameter (D1) larger than an internal diameter (DS) of the perforation or of a sleeve inserted into the perforation; inserting the fastener and the cap into the perforation or the sleeve, the cap enters the perforation or sleeve first and lubricates the interior surface of the perforation or the sleeve when its largest external diameter is radially compressed by a wall of the perforation or of the sleeve. ### Claim 15 (depends on 14) The assembly process according to claim 14, comprising a subsequent step in which the cap is removed from the fastener, before installation of a nut or a collar on the fastener.