B21L MAKING METAL CHAINS (making chains or chain links by casting B22D25/02; chains in general F16G)
Description
B21L covers mechanical processes and machinery for manufacturing metal chains without substantial material removal. This subclass encompasses chain fabrication methods including welding, forming, and assembling of chain links, along with associated equipment such as linking machines, welding apparatus, and quality control devices. Typical applications include production of conveyor chains, lifting chains, and decorative chains from ferrous and non-ferrous metals. Excluded are drawing operations for wire or rod preparation (covered under B21B) and operations that involve significant material removal such as cutting or grinding of finished chain components.
Filing statistics
CPC subclass B21L recorded 983 patent applications worldwide between 2013 and 2023. Annual filings grew from 58 in 2013 to 58 in 2023 (+0%), peaking at 143 applications in 2018. The most active applicants in class B21 are JFE STEEL (2,667 applications), NIPPON STEEL CORPORATION (2,049 applications) and POSCO (POHANG IRON AND STEEL COMPANY) (1,967 applications).
Source: EPO PATSTAT, worldwide filings
11 direct subcodes
Child Classifications
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- B21L 1/00 Making chains or chain links by bending workpieces of rod, wire, or strip to form links of oval or other simple shape (B21L3/00, B21L7/00 take precedence)
- B21L 11/00 Making chains or chain links of special shape
- B21L 13/00 Making terminal or intermediate chain links of special shape; Making couplings for chains, e.g. swivels, shackles
- B21L 15/00 Finishing or dressing chains or chain links, e.g. removing burr material, calibrating (B21L9/06 takes precedence)
- B21L 19/00 Appurtenances for chain-making not restricted to any particular process
- B21L 21/00 Tools or implements for repairing chains using metal-working operations, e.g. for detaching deformed chain links
- B21L 3/00 Making chains or chain links by bending the chain links or link parts and subsequently welding or soldering the abutting ends (B21L7/00 takes precedence)
- B21L 5/00 Making chains or chain links by working the starting material in such a way that integral, i.e. jointless, chains links are formed
- B21L 7/00 Making chains or chain links by cutting single loops or loop-parts from coils, assembling the cut parts and subsequently subjecting same to twisting with or without welding
- B21L 9/00 Making chains or chain links, the links being composed of two or more different parts, e.g. drive chains (B21L1/04, B21L7/00, B21L11/14, B21L13/00 take precedence)
- B21L 99/00 Subject matter not provided for in other groups of this subclass
Top Applicants
Top 10 applicants by patent filingsfor class B21, 2013–2023, worldwide · Source: EPO PATSTAT
- JFE STEEL JP 2,667
- NIPPON STEEL CORPORATION JP 2,049
- POSCO (POHANG IRON AND STEEL COMPANY) KR 1,967
- NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 1,800
- SMS GROUP DE 1,538
- JFE STEEL 1,150
- ARCELORMITTAL LU 1,142
- BAOSHAN IRON & STEEL COMPANY 821
- HYUNDAI STEEL COMPANY KR 808
- THYSSENKRUPP STEEL EUROPE DE 660