Cold Rolling & Annealing Line Patents: Top Companies & Trends 2026
- Five companies hold 78.9% of the field. 116 of 147 records in scope sit with the top five assignees, leaving a long tail of single- and double-digit filers.
- Filing peaked in 2023 at 15 records and has since flattened. The 2022 midpoint sits at just 1 record, and growth from there is flat or declining rather than accelerating.
- Japan dominates the receiving offices with 74 filings. Europe (22), the United States (14) and China (9) trail well behind, pointing to where enforcement priority actually sits.
A mature, concentrated field with flat recent filing
Cold rolling mills and continuous annealing lines are among the oldest continuously patented areas of steel processing, and the record set reflects that maturity: heat treatment classifications (C21D) touch 68.7% of the 147 records in scope, metal rolling (B21B) touches 44.9%, and alloy composition (C22C) touches 40.1%. These three classes overlap heavily on individual records, which is expected in a domain where strip shape control, recrystallization annealing and alloy chemistry are claimed together rather than separately. The most-cited records in the set date from the 1980s and 1990s, which says more about citation accumulation time than about where current activity sits.
Ownership is concentrated: the leading assignee accounts for 40 of the 147 records, and the ranked list of 30 companies drops to single digits by the tenth position. Filing has not grown steadily — the trend peaked in 2023 at 15 records after a near-empty 2022, and the most recent year is necessarily undercounted because publication typically lags filing by around 18 months.
Let an AI agent run this analysis on your own technology
Pick a task. Every answer cites the patents behind it.
Filing trend and technology composition
These figures come directly from the 147 records in scope and are not projected or smoothed; read the most recent year as a floor, not a ceiling.
Filing has flattened after a 2023 peak
The trend runs from zero in 2017 to a peak of 15 records in 2023, with a near-empty midpoint of 1 record in 2022 — a pattern consistent with a mature technology where filing responds to specific process innovations rather than steady investment.
Heat treatment and rolling classes dominate, alloys close behind
C21D (heat treatment) appears on 68.7% of records, B21B (metal rolling) on 44.9%, and C22C (alloys) on 40.1%; coating (C23C), magnetics (H01F) and extrusion (B21C) each sit under 10%, marking them as adjacent rather than core to this claim set.
Shares are the percentage of the 147 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Cold Rolling and Continuous Annealing Lines with Eureka
This page is one run against one query. Ask Eureka your own question about cold rolling and continuous annealing lines and every answer comes back with the patent numbers behind it.
Try EurekaThe documents anchoring this landscape
US4330112A — Apparatus for cooling a steel strip in a continuous annealing line
Method and apparatus for cooling a steel strip in a continuous annealing line, with a first cooling step that takes the strip from overageing temperature down to 95–60°C in a protective atmosphere using a liquid coolant to prevent surface oxidation while allowing self-drying, followed by a second cooling step to below 40°C in preparation for temper rolling.Filed by Nippon Steel Corporation, dated 1982-05-18 — one of the most-cited records in this set at 28 citations.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | JP2016153138A | Vibration abnormality detection method and device for cold rolling or temper rolling | 39 |
| 2 | US5706690A | Twin stand cold reversing mill | 39 |
| 3 | JP1992000350A | Cold rolled high tensile strength steel sheet excellent in stretch flange characteristic, hot-dip galvanized … | 36 |
| 4 | US4481800A | Cold rolling mill for metal strip | 32 |
| 5 | US4330112A | Apparatus for cooling a steel strip in a continuous annealing line | 28 |
| 6 | JP1987224405A | Production of cold rolled steel sheet | 21 |
| 7 | GB2086425A | Continuous annealing process for producing ageing-resistant mild steel sheet | 19 |
| 8 | JP1994179922A | Production of high tensile strength steel sheet for deep drawing | 18 |
| 9 | JP1983025436A | Manufacture of deep drawing cold rolling steel plate having slow aging property and small anisotropy | 18 |
| 10 | JP1986163216A | Manufacture of ferritic stainless steel sheet superior in surface property and workability | 16 |
Citation counts favour older records that have had more time to accumulate citations within this searched corpus; treat them as a signal of influence, not of current commercial relevance.
Each row carries its publication number; clicking a row searches Eureka by that number.
Put your own technology through the same analysis
Eureka on the web
When you want the answer in the next five minutes.
The agent works the prompt against patents and technical literature, citing every source.
Run your analysis now →MCP server & REST API
When it has to run inside your own pipeline.
Patent search, landscape analysis and assignee resolution as MCP tools. Drop them into any agent framework, or call REST directly.
Browse MCP servers →What the numbers mean for filing strategy
Three patterns stand out once the ranking, trend and class composition are read together.
Five assignees control most of the claim space
The top five combined account for 116 of the 147 records in scope, and the leader alone holds 40. New entrants are filing into a field where core rolling and annealing process claims are already dense.
Growth is flat, not accelerating
After a peak of 15 records in 2023, the trend has not sustained upward movement; the 2022 midpoint of just 1 record shows filing arrives in bursts tied to specific process developments rather than steady investment.
Enforcement priority sits heavily in Japan
Japan receives 74 of the tracked filings, more than three times the next office (EPO at 22). The United States (14), China (9), the UK (8) and India (6) represent secondary but still active filing destinations.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to cold rolling and continuous annealing lines, with the prior art for and against each one.
| Assignee | Co-assignee | Shared families |
|---|---|---|
| Nippon Steel Corporation | Nittetsu Plant Designing Corp | 3 |
| Sumitomo Metal Industries Ltd | Kyodo Yushi Co., Ltd. | 2 |
| Sumitomo Metal Industries Ltd | Mitsubishi Heavy Industries Ltd | 2 |
| Nippon Steel Corporation | Mishima Kosan Co., Ltd. | 1 |
| Nippon Kokan KK | Ishikawajima-Harima Heavy Industries Co., Ltd. | 1 |
Only 5 co-assignee pairs appear in the dataset, the strongest linking a major steelmaker with its own plant-engineering affiliate — consistent with in-house process development rather than cross-company joint filing.
Who holds the ground, and where it thins out
The ranking runs to 30 companies with a steep drop after the top tier; recent-year momentum across the leading names has flattened to zero.
A single steelmaker leads the field outright
The top-ranked assignee holds 40 of the 147 records in scope, well ahead of the fifth-place holder at 12 — a gap wide enough that competitive filing strategy has to treat this leader as the reference point for prior art searches.
The mid-tier holds double digits, then drops sharply
Fifth place sits at 12 records; by tenth place the count is down to 2. That drop marks where the ranking moves from established steelmakers and equipment builders to a long tail of occasional filers.
Recent-year activity has gone quiet across the top names
Every major assignee tracked for recent-year momentum, including the field leader and several others in the top tier, shows zero filings in the latest year, with some down 100% year-on-year. This is consistent with the broader flat trend rather than a single company's retreat.
| Assignee | Recent year | YoY |
|---|---|---|
| JFE Steel Corp | 0 | -100% |
| Nippon Steel Corporation | 0 | — |
| Kawasaki Steel Corp | 0 | — |
| Sumitomo Metal Industries Ltd | 0 | — |
| Nippon Kokan KK | 0 | — |
| Tata Steel IJmuiden BV | 0 | -100% |
| Andritz AG | 0 | — |
| Tetsugen Corporation | 0 | — |
Where to take this analysis
The dataset points to a mature field with a narrow set of controlling assignees; the next steps depend on whether the goal is freedom-to-operate or identifying open ground.
Map claims against the leader's portfolio
With one assignee holding 40 of 147 records, any new filing in core rolling or annealing process control should be checked against that portfolio first, not just the aggregate ranking.
Run a freedom-to-operate check in EurekaTrack the under-claimed adjacent classes
Coating, magnetics and extrusion classes each sit under 10% of records — worth monitoring for early filings before they consolidate the way core rolling claims have.
Set up class-level monitoring in EurekaCommon questions about this landscape
One assignee leads the ranked list of 30 companies with 40 of the 147 records in scope, well ahead of the fifth-place holder at 12. The top five combined hold 116 records, or 78.9% of all records in scope, meaning most of the claim space in this dataset sits with a small group of established steelmakers and their plant-engineering affiliates. Anyone filing new claims in core rolling or annealing process control should treat that leading portfolio as the primary prior-art reference.
Filing is flat to declining rather than growing. The trend peaked at 15 records in 2023, but the 2022 midpoint sits at just 1 record, and recent-year momentum data shows several leading assignees at zero filings with some down 100% year-on-year. Because publication typically lags filing by around 18 months, the most recent year in any such trend is always undercounted, but the multi-year pattern points to a mature, not expanding, filing base.
Heat treatment (IPC class C21D) appears on 68.7% of the 147 records in scope, metal rolling (B21B) on 44.9%, and alloy composition (C22C) on 40.1%. These three classes overlap heavily because strip shape control, recrystallization annealing and alloy chemistry are typically claimed together in a single record. Coating and surface deposition (C23C), magnetics (H01F) and extrusion (B21C) each touch under 10% of records, marking them as adjacent rather than core.
Japan is by far the largest receiving office with 74 filings, more than three times the next largest office. Europe via the EPO follows at 22, the United States at 14, China at 9, the United Kingdom at 8, and India at 6. This distribution reflects where the leading steelmakers in this dataset are headquartered and where they prioritise enforcement, rather than where the underlying manufacturing capacity is largest.
Core rolling and heat-treatment process claims are dense, but several adjacent classes remain under 10% of records, including coating and surface deposition, magnetic-grade annealing applications, and extrusion/drawing tie-ins. These lower-density classes are where a first-mover claim is more likely to clear prior art cleanly, though a formal freedom-to-operate search against the leading assignee's specific claims is still necessary before filing.
Research Cold Rolling and Continuous Annealing Lines in depth with Eureka
Go past this page: query the whole cold rolling and continuous annealing lines corpus yourself, in your own scope.
Every answer comes back with patent numbers you can open.
Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.