# US 8,770,003 B2 · Method for producing seamless pipe and method for determining length of billet for use in producing seamless pipe > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,003 B2 - Document ID: US8770003B2 - Status: Granted - Kind: B2 - Application number: 12/883,887 - Filed: 2010-09-16 - Published: 2011-03-10 - Granted: 2014-07-08 - Earliest claimed: 2008-03-25 - Assignees: Sumitomo Metal Industries, Ltd. - Applicants: Kenichi Sasaki - Inventors: Kenichi Sasaki - Web page: https://patentgrep.com/patent/US8770003B2 ## CPC - B21B 23/00: Tube-rolling not restricted to methods provided for in only one of groups B21B17/00, B21B19/00, B21B21/00, e.g. combined processes {planetary tube rolling, auxiliary arrangements, e.g. lubricating, special tube blanks, continuous casting combined with tube rolling}(B21B25/00 takes precedence) - B21B 19/04: Rolling basic material of solid, i.e. non-hollow, structure; Piercing {, e.g. rotary piercing mills} - B21B 2015/0014: {transversely to the rolling direction} - B21B: ROLLING OF METAL (auxiliary operations used in connection with metal-working operations covered in B21, see B21C; bending by rolling B21D; manufacture of particular objects, e.g. screws, wheels, rings, barrels, balls, by rolling B21H; pressure welding by means of a rolling mill B23K20/04) ## Abstract Seamless pipes are produced by using billets for which the length L of a parent billet, the lengths l of child billets and the number nB of the obtainable child billets are determined on the basis of predetermined tolerances and the conditions of a billet-heating furnace and billet-rolling facilities. In this way, energy saving in the production of seamless pipes can be realized and the productivity in the production of seamless pipes can also be improved. ## Claims ### Claim 1 A method for producing a seamless pipe comprising steps of a billet-heating process, a billet-cutting process, a piercing-rolling process and elongation-rolling process, wherein: the method using the billets satisfying the following formulas (1) to (3): lmin≦l≦lmax (1) LminL≦Lmax (2) F≧Fmin (3) wherein L is the length (m) of the parent billet and is represented by the following formula (4), and F is the billet-heating-furnace filling factor (%) and is represented by the following formula (5): L=l×nB+k×(nB−1) (4) F=100×L/Lmax (5) wherein in the above-described formulas, the meanings of the individual symbols are as follows: Lmin: The minimum length (m) of the parent billet allowed on the basis of the conditions of the billet-heating furnace Lmax: The maximum length (m) of the parent billet allowed on the basis of the conditions of the billet-heating furnace l: The length (m) of the child billet lmin: The minimum value (m) of the length of the child billet allowed on the basis of the predetermined tolerances and the rolling conditions lmax: The maximum value (m) of the length of the child billet allowed on the basis of the predetermined tolerances and the rolling conditions k: Billet cutting margin (m) nB: The number (number of pieces) of the child billets obtainable from one piece of parent billet Fmin: The allowable minimum value (%) of the heating-furnace filling factor wherein, the method adopts the following respective values in the following respective cases (A) to (C) in each of which the relation between the number-of-obtainable-billet indexes I0 and Il calculated respectively from the following formulas (6) and (7) is specified: (A) A case where I0=Il: L obtained by substituting nB=I0 and l=lmax into the above-described formula (4) is adopted as the length L of the parent billet, lmaxis adopted as the length l of the child billet, and I0 is adopted as the number nB of the obtainable child billets (B) A case where I0