# US 10,662,993 B2 · High-strength screw including an unhardened thread end > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,662,993 B2 - Document ID: US10662993B2 - Status: Granted - Kind: B2 - Application number: 15/886,031 - Filed: 2018-02-01 - Published: 2018-08-02 - Granted: 2020-05-26 - Earliest claimed: 2017-02-01 - Assignees: KAMAX Holding GmbH & Co. KG - Applicants: KAMAX Holding GmbH & Co. KG - Inventors: Frank Wagner; Harald Frischkorn - Web page: https://patentgrep.com/patent/US10662993B2 ## CPC - F16B 33/02: Shape of thread; Special thread-forms ({F16B25/00 takes precedence; used to remove paint or dirt layers F16B35/007, F16B37/002}; used as screw-locking device F16B39/30) - B23G 9/001: {Working screws} - C21D 1/25: Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten") - C21D 8/06: during manufacturing of rods or wires - C21D 9/0093: {for screws; for bolts} - 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) - C21D 2211/002: Bainite - F16B 33/04: in view of tensile load - 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) - B23G: THREAD CUTTING; WORKING OF SCREWS, BOLT HEADS, OR NUTS, IN CONJUNCTION THEREWITH (making helical grooves by turning B23B5/48, by milling B23C3/32, by forging, pressing, or hammering B21K1/56, by grinding B24B19/02; arrangements for copying or controlling B23Q; thread-forming by corrugating tubes B21D15/04, by rolling B21H3/02) - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) ## Abstract A high-strength screw (1) includes a head (2) and a threaded portion (5) including a thread (6) and a thread end (9) facing away from the head (2) in an axial direction. The threaded portion (5) includes an unhardened portion (12) starting at the thread end (9) and extending in an axial direction. The unhardened portion (12) has a hardness being reduced compared to an axial middle portion (11) of the threaded portion (5). ## Claims ### Claim 1 A high-strength screw, comprising: a head; and a shank defining an axial direction and including a threaded portion including a thread, the threaded portion having a first thread end facing away from the head in the axial direction, the threaded portion having a second thread end facing the head in the axial direction, the threaded portion having an axial middle portion being located in the middle between the first thread end and the second thread end, the axial middle portion having a first hardness, and the threaded portion including an unhardened portion, the unhardened portion starting at the first thread end and extending in the axial direction towards the head, the unhardened portion having a second hardness being reduced compared to the first hardness of the axial middle portion. ### Claim 2 (depends on 1) The screw of claim 1, wherein the second hardness of the unhardened portion is at least 50 HV lower than the first hardness of the axial middle portion. ### Claim 3 (depends on 1) The screw of claim 1, wherein the second hardness of the unhardened portion is between 50 HV and 300 HV lower than the first hardness of the axial middle portion. ### Claim 4 (depends on 1) The screw of claim 1, wherein the second hardness of the unhardened portion is between 100 HV and 250 HV lower than the first hardness of the axial middle portion. ### Claim 5 (depends on 1) The screw of claim 1, wherein the axial middle portion has a first tensile strength, the unhardened portion has a second tensile strength, the second tensile strength of the unhardened portion being at least 100 N/mm2 lower than the first tensile strength of the axial middle portion. ### Claim 6 (depends on 1) The screw of claim 1, wherein the axial middle portion has a first tensile strength, the unhardened portion has a second tensile strength, the second tensile strength of the unhardened portion being between 100 N/mm2 and 700 N/mm2 lower than the first tensile strength of the axial middle portion. ### Claim 7 (depends on 1) The screw of claim 1, wherein the axial middle portion has a first tensile strength, the unhardened portion has a second tensile strength, the second tensile strength of the unhardened portion being between 200 N/mm2 and 500 N/mm2 lower than the first tensile strength of the axial middle portion. ### Claim 8 (depends on 1) The screw of claim 1, wherein the second hardness of the unhardened portion is between 15% and 50% lower than the first hardness of the axial middle portion. ### Claim 9 (depends on 1) The screw of claim 1, wherein the second hardness of the unhardened portion is between 20% and 40% lower than the first hardness of the axial middle portion. ### Claim 10 (depends on 1) The screw of claim 1, wherein the axial middle portion has a first tensile strength, the unhardened portion has a second tensile strength, the second tensile strength of the unhardened portion being between 15% and 50% lower than the second tensile strength of the axial middle portion. ### Claim 11 (depends on 1) The screw of claim 1, wherein the axial middle portion has a first tensile strength, the unhardened portion has a second tensile strength, the second tensile strength of the unhardened portion being between 20% and 40% lower than the second tensile strength of the axial middle portion. ### Claim 12 (depends on 1) The screw of claim 1, wherein the thread has a pitch, the unhardened portion has an axial length, the axial length extending over at least twice the pitch. ### Claim 13 (depends on 1) The screw of claim 1, wherein the thread has a pitch, the unhardened portion has an axial length, the axial length extending over at least three times the pitch. ### Claim 14 (depends on 12) The screw of claim 12, wherein the axial length extends over a maximum of one selected from the group consisting of: eight times, seven times and six times the pitch. ### Claim 15 (depends on 13) The screw of claim 13, wherein the axial length extends over a maximum of one selected from the group consisting of: eight times, seven times and six times the pitch. ### Claim 16 (depends on 1) The screw of claim 1, wherein the thread being located in the unhardened portion has a standard design as far as geometry is concerned. ### Claim 17 (depends on 16) The screw of claim 16, wherein no bore is arranged in the unhardened portion. ### Claim 18 (depends on 1) The screw of claim 1, wherein the screw includes a bainite structure.