| B | SK | PERFORMING OPERATIONS; TRANSPORTING |
| B21 | USK | SHAPING |
| B21 | KL | MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL (casting, powder metallurgy B22; shearing B23D; working of metal by the action of a high concentration of electric current B23H; soldering, welding, flame-cutting B23K; other working of metal B23P; punching sheet material in general B26F; processes for changing of physical properties of metals C21D , C22F; electroforming C25D 1/00) |
| B21L | UKL | MAKING CHAINS (chains in general F16G) |
| B21L 1/00 | HGR | Making chains or chain links by bending workpieces of rod, wire, or strip to form links of oval or other simple shape (B21L 3/00 , B21L 7/00 take precedence) |
| B21L 1/02 | UGR1 | | . | by bending the ends of the workpieces to abut |
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| B21L 1/04 | UGR1 | | . | by bending and interconnecting the ends of the workpieces with or without separate jointing members |
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| B21L 3/00 | HGR | Making chains or chain links by bending the chain links or link parts and subsequently welding or soldering the abutting ends (B21L 7/00 takes precedence) |
| B21L 3/02 | UGR1 | | . | Machines or devices for welding chain links |
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| B21L 3/04 | UGR2 | | . . | by making use of forge or pressure welding |
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| B21L 5/00 | HGR | Making chains or chain links by working the starting material in such a way that integral, i.e. jointless, chain links are formed |
| B21L 5/02 | UGR1 | | . | in such a way that interconnected links are formed |
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| B21L 7/00 | HGR | 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 | HGR | Making chains or chain links, the links being composed of two or more different parts, e.g. drive chains (B21L 1/04 , B21L 7/00 , B21L 11/14 , B21L 13/00 take precedence) |
| B21L 9/02 | UGR1 | | . | of roller-chain or other plate-link type |
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| B21L 9/04 | UGR2 | | . . | Punching or bending the different parts of the chain links |
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| B21L 9/06 | UGR2 | | . . | Sorting, feeding, assembling, riveting, or finishing parts of chains |
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| B21L 9/08 | UGR2 | | . . | Combining the chain links with auxiliary parts, e.g. welding-on wear-resistant parts |
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| B21L 11/00 | HGR | Making chains or chain links of special shape |
| B21L 11/02 | UGR1 | | . | each link being formed of a single member of which both ends are bent or shaped to engage the middle portion of the next link |
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| B21L 11/04 | UGR2 | | . . | the ends being pierced or punched to form eyes |
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| B21L 11/06 | UGR3 | | . . . | the workpiece being of thin strip metal |
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| B21L 11/08 | UGR2 | | . . | the ends being interengaged with other parts of the same link |
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| B21L 11/10 | UGR1 | | . | the chain links having opposed correspondingly shaped cylindrical and hook-like parts of which one part forms a hinge-like support for the adjacent link (B21L 11/02 takes precedence) |
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| B21L 11/12 | UGR1 | |
| B21L 11/14 | UGR1 | | . | Making chain links with inserted or integrally- formed studs |
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| B21L 13/00 | HGR | Making terminal or intermediate chain links of special shape; Making couplings for chains, e.g. swivels, shackles |
| B21L 15/00 | HGR | Finishing or dressing chains or chain links, e.g. removing burr material, calibrating (B21L 9/06 takes precedence) |
| B21L 15/02 | UGR1 | | . | Twisting already closed links |
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| B21L 17/00 | HGR | Making chains or chain links not covered by one of the preceding main groups (by casting B22D 25/02) |
| B21L 19/00 | HGR | Appurtenances for chain-making not restricted to any particular process |
| B21L 21/00 | HGR | Tools or implements for repairing chains using metal-working operations, e.g. for detaching deformed chain links |