CPC Main Group
B21K 21/00 Making hollow articles not covered by a single preceding sub-group (essentially from sheet-metal or uniform thin-walled tubes B21D, e.g. B21D41/00, B21D51/00)
Filing statistics
CPC B21K 21/00 belongs to the parent subclass B21K, which recorded 12,578 patent applications worldwide between 2013 and 2023. Annual filings grew from 997 in 2013 to 1,026 in 2023 (+3%), peaking at 1,339 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
6 direct subcodes
Child Classifications
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- B21K 21/02 Producing blanks in the shape of discs or cups as semifinished articles for making hollow articles, e.g. to be deep-drawn or extruded
- B21K 21/04 Shaping thin-walled hollow articles, e.g. cartridges
- B21K 21/06 Shaping thick-walled hollow articles, e.g. projectiles
- B21K 21/08 Shaping hollow articles with different cross-section in longitudinal direction, e.g. nozzles, spark-plugs
- B21K 21/12 Shaping end portions of hollow articles
- B21K 21/16 Remodelling hollow bodies with respect to the shape of the cross-section (remodelling end portions only B21K21/12)
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