# US 8,784,030 B2 · Screw having an underhead bearing surface including lubricant pockets > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,784,030 B2 - Document ID: US8784030B2 - Status: Granted - Kind: B2 - Application number: 13/737,154 - Filed: 2013-01-09 - Published: 2013-07-18 - Granted: 2014-07-22 - Earliest claimed: 2012-01-12 - Assignees: KAMAX Holding GmbH & Co. KG - Applicants: KAMAX Holding GmbH & Co. KG - Inventors: Markus Grobecker; Norbert Bietz; Gunther Hartmann - Web page: https://patentgrep.com/patent/US8784030B2 ## CPC - F16B 35/00: Screw-bolts; Stay-bolts; Screw-threaded studs; Screws; Set screws ({F16B33/008 takes precedence; joining sheets or plates using screws with two separate threads F16B5/0275; using screws with adjustment sleeves F16B5/0283}; thread cutting screws F16B25/00) - 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)} - F16B 35/06: Specially-shaped heads (special shape in order to rotate the bolt F16B23/00 {; separate hook adaptors for bolts F16B43/025}) - F16B 43/002: {with special provisions for reducing friction} - 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) ## Abstract A screw (2) has a head (5) including an underhead bearing surface (12). Lubricant pockets (13) are arranged at least in a part of the underhead bearing surface (12). The lubricant pockets (13) serve to contain lubricant and to release the lubricant when tightening a screw joint (1) to prevent galling effects during multiple tightening processes. ## Claims ### Claim 1 A screw, comprising: a head, the head having an underhead bearing surface, the underhead bearing surface having a radial direction, a circumferential direction and a radial width; and a plurality of lubricant pockets containing lubricant, the lubricant pockets being designed as cold formed lubricant pockets, the lubricant pockets being arranged at least in a part of the underhead bearing surface, the lubricant pockets being arranged in an irregular way, the lubricant pockets being designed not to be continuous in the radial direction and in the circumferential direction of the underhead bearing surface, and the lubricant pockets having an average diameter of between approximately 50 to 500 μm and corresponding to approximately maximally 20% of the radial width of the underhead bearing surface. ### Claim 2 (depends on 1) The screw of claim 1, wherein the lubricant pockets are designed to be circumferentially closed as seen in cross-section. ### Claim 3 (depends on 1) The screw of claim 1, wherein the lubricant pockets are only arranged in a part of the underhead bearing surface. ### Claim 4 A screw joint, comprising: a component including a surface and a bore; a screw having a head including an underhead bearing surface, the screw extending through the bore of the component; a washer having a first surface and an opposite second surface, the washer being arranged between the underhead bearing surface of the screw and the surface of the component, the first surface of the washer beinq arranged to face the underhead bearing surface of the screw and the second surface of the washer being arranged to face the surface of the component; and a plurality of lubricant pockets, the lubricant pockets being designed as cold formed lubricant pockets and being arranged in at least a part of the underhead bearing surface of the screw. ### Claim 5 (depends on 4) The screw joint of claim 4, wherein a plurality of lubricant pockets is arranged at least in a part of the first surface of the washer. ### Claim 6 (depends on 4) The screw joint of claim 4, wherein the lubricant pockets are designed to be circumferentially closed as seen in cross-section. ### Claim 7 (depends on 4) The screw joint of claim 4, wherein the lubricant pockets have an average diameter of between approximately 50 to 500 μm. ### Claim 8 (depends on 4) The screw joint of claim 4, wherein the lubricant pockets have an average diameter of between approximately 100 to 300 μm. ### Claim 9 A screw, comprising: a head, the head having an underhead bearing surface; and a plurality of lubricant pockets, the lubricant pockets being designed as cold formed lubricant pockets and being arranged at least in a part of the underhead bearing surface. ### Claim 10 (depends on 9) The screw of claim 9, wherein the lubricant pockets are designed to be circumferentially closed as seen in cross-section. ### Claim 11 (depends on 10) The screw of claim 10, wherein the underhead bearing surface has a radial direction and a circumferential direction, the lubricant pockets being arranged to be distributed in an irregular way and that they are designed not to be continuous in the radial direction and in the circumferential direction of the underhead bearing surface. ### Claim 12 (depends on 9) The screw of claim 9, wherein the underhead bearing surface has a radial direction and a circumferential direction, the lubricant pockets being arranged to be distributed in an irregular way and that they are designed not to be continuous in the radial direction and in the circumferential direction of the underhead bearing surface. ### Claim 13 (depends on 9) The screw of claim 9, wherein the underhead bearing surface has a radial width, the lubricant pockets having an average diameter corresponding to approximately maximally 20% of the radial width of the underhead bearing surface. ### Claim 14 (depends on 9) The screw of claim 9, wherein the lubricant pockets have an average diameter of between approximately 50 to 500 μm. ### Claim 15 (depends on 9) The screw of claim 9, wherein the lubricant pockets have an average diameter of between approximately 100 to 300 μm. ### Claim 16 (depends on 9) The screw of claim 9, wherein the underhead bearing surface has an average surface roughness Rz of between approximately 10 to 100 μm for forming the lubricant pockets. ### Claim 17 (depends on 9) The screw of claim 9, wherein the underhead bearing surface has an average surface roughness Rz of between approximately 15 to 50 μm for forming the lubricant pockets. ### Claim 18 (depends on 9) The screw of claim 9, wherein the underhead bearing surface includes projecting portions and deepened portions, the deepened portions forming the lubricant pockets, the projecting portions being designed to be rounded and to have an average diameter of between approximately 50 to 500 μm. ### Claim 19 (depends on 9) The screw of claim 9, wherein the underhead bearing surface includes projecting portions and deepened portions, the deepened portions forming the lubricant pockets, the projecting portions being designed to be rounded and to have an average diameter of between approximately 100 to 300 μm. ### Claim 20 (depends on 9) The screw of claim 9, wherein the lubricant pockets are only arranged in a part of the underhead bearing surface. ### Claim 21 (depends on 9) The screw of claim 9, wherein the underhead bearing surface has radial outer part, the lubricant pockets only being arranged in the radial outer part. ### Claim 22 A washer for combination with a screw, the screw having a head including an underhead bearing surface, the washer comprising: a first surface facing the underhead bearing surface of the screw; and a plurality of lubricant pockets, the lubricant pockets being designed as cold formed lubricant pockets and being arranged at least in a part of the first surface. ### Claim 23 (depends on 22) The washer of claim 22, wherein the lubricant pockets are designed to be circumferentially closed as seen in cross-section. ### Claim 24 (depends on 22) The washer of claim 22, wherein the first surface has a radial direction and a circumferential direction, the lubricant pockets being arranged to be distributed in an irregular way and that they are designed not to be continuous in the radial direction and in the circumferential direction of the first surface. ### Claim 25 (depends on 22) The washer of claim 22, wherein the first surface has a radial width, the lubricant pockets having an average diameter corresponding to approximately maximally 20% of the radial width of the first surface. ### Claim 26 (depends on 22) The washer of claim 22, wherein the lubricant pockets have an average diameter of between approximately 50 to 500 μm. ### Claim 27 (depends on 22) The washer of claim 22, wherein the lubricant pockets have an average diameter of between approximately 100 to 300 μm. ### Claim 28 (depends on 22) The washer of claim 22, wherein the first surface has an average surface roughness Rz of between approximately 10 to 100 μm for forming the lubricant pockets. ### Claim 29 (depends on 22) The washer of claim 22, wherein the first surface has an average surface roughness Rz of between approximately 15 to 50 μm for forming the lubricant pockets. ### Claim 30 A screw, comprising: a head, the head having an underhead bearing surface; and a plurality of lubricant pockets, the lubricant pockets being only arranged in a part of the underhead bearing surface.