Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
  • B21C37/00—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape
  • B21C37/06—Manufacture of metal sheets, rods, wire, tubes, profiles or like semi-manufactured products, not otherwise provided for; Manufacture of tubes of special shape of tubes or metal hoses; Combined procedures for making tubes, e.g. for making multi-wall tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B19/00—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work
  • B21B19/02—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work the axes of the rollers being arranged essentially diagonally to the axis of the work, e.g. "cross" tube-rolling ; Diescher mills, Stiefel disc piercers or Stiefel rotary piercers
  • B21B19/04—Rolling basic material of solid, i.e. non-hollow, structure; Piercing, e.g. rotary piercing mills
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21J—FORGING; HAMMERING; PRESSING METAL; RIVETING; FORGE FURNACES
  • B21J5/00—Methods for forging, hammering, or pressing; Special equipment or accessories therefor
  • B21J5/06—Methods for forging, hammering, or pressing; Special equipment or accessories therefor for performing particular operations
  • B21J5/10—Piercing billets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
  • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
  • B21B1/466—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a non-continuous process, i.e. the cast being cut before rolling
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B23/00—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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
  • B21B3/02—Rolling special iron alloys, e.g. stainless steel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
  • B21H1/00—Making articles shaped as bodies of revolution
  • B21H1/06—Making articles shaped as bodies of revolution rings of restricted axial length
  • B21H1/12—Making articles shaped as bodies of revolution rings of restricted axial length rings for ball or roller bearings

Definitions

• the invention relates to a method for producing a hot-formed tube from high-carbon, in particular hypereutectoid steel, according to the preamble of the main claim.
• a block is cast, which is rolled on a roughing mill to a tube round.
• This round tube is preferably formed into a hot-finished tube using the Assel method (see Stahlrohr-Handbuch 10th Edition, Vulkan-Verlag, Essen, 1986, pages 141-143).
• Assel-Strasse usually has a rotary hearth furnace as the heating system, followed by a perforated machine designed as an inclined roller mill to produce a hollow body.
• This hollow body is fed to an Assel rolling mill consisting of three diagonally arranged diagonally distributed rollers, which are equipped with a shoulder calibration. After pulling out the rod that serves as the internal tool, this becomes The intermediate pipe is reheated and the hot-produced pipe is generated via a multi-stand reducing roll mill and a downstream sizing mill.
• a disadvantage of this method is that the tube round used must be close to the dimension of the hot-finished tube and a large number of rolled or forged tube round material is required to cover the delivery program.
• the Assel Street is the preferred plant for the production of roller bearing tubes, but other tube production systems, such as push bench systems or tube continuous lines, are always used using pre-deformed and diffusion-annealed feed material.
• the object of the invention is to provide a method for producing a hot-formed tube from high-carbon, in particular hypereutectoid steel, which is cheaper in comparison to the known methods and with which a higher material utilization and a shorter material throughput time can be achieved.
• This object is achieved with the features specified in the characterizing part of the main claim.
• Advantageous further developments are part of subclaims.
• the essence of the invention is the use of undeformed continuous casting from steel, in particular from the material group of rolling bearing steels of any cross-section on a tube production system, eliminating the previously required upstream rolling or forging process and dispensing with the diffusion annealing required by the prior art considerable cost and time.
• the material is used better, since it does not have to be divided and scooped as often.
• care must be taken to ensure that, in the hole process as part of the overall process of tube production equipment, a stress state is built up in the length to be reshaped that has the highest possible negative mean stress value s m while minimizing shear stresses.
• the method according to the invention can be used for all types of continuous casting such as vertical casting or sheet casting and regardless of the cross section, i. H. whether square, octagonal, polygonal or round.
• Continuous casting block is divided into insert lengths without pre-deformation, i.e. H. in the as-cast state, heated to the forming temperature and then fed to the tube production system.
• the push bench and the drawing press method have proven to be particularly advantageous. In all of the methods mentioned, the heated insert length for the punching process is placed in a round die and at
• the use of direct continuous casting requires continuous casting, which has a homogeneous and finely dispersed distribution of the primary carbides and a high degree of purity and is as fine-grained as possible, characteristics which are guaranteed by the melting and casting process explained below.
• the high degree of purity is necessary because the non-metallic inclusions that are unavoidably produced in steel production are retained in their original particle size and number per unit of mass until they are used as tube raw material and are not stretched and changed by deformation. This relationship applies equally to the average grain size.
• the reduction of the coarse carbide precipitates is connected with the elimination of the diffusion annealing that has been customary up to now, which in the conventional method ensures a concentration compensation of the carbon and a homogenization of the structure.
• modified metallurgy and special measures for casting the continuous casting are provided as measures according to the invention.
• This also includes an adapted casting speed in the range preferably from 1.8 to 1.2 m / min. for the dimension range 170 - 240 mm D.
• the casting speed ranges given above make it easier for the bubbles and inclusions to rise in the sense of a high degree of purity, but are selected so that the desired fine grain size is not impaired.
• the rapid solidification with the relatively small cross-sections leads to a structure with a high degree of fine-grain even in the as-cast state and at the same time prevents this
• the aluminum content must be selected so that the amount of AI2O3 formed in the cast continuous casting is small. For this reason, no aluminum is added in the process according to the invention without the oxygen content assuming undesirable values. Dispensing with the addition of Al does not mean that there are no traces of Al in the melt, either because of the low Al content of the alloy components or because of the lining.
• the method according to the invention uses of undeformed and non-diffusion-annealed continuous casting of preferably hypereutectoid steel for the production of seamless roller bearing tubes on a tube production system with a punch press, in which a compression stress state during punching arises through the choice of the forming conditions.
• a hot-rolled pipe with the dimensions 60.3 D and 8.0 mm wall made of 100Cr ⁇ bearing steel is to be produced.
• a pig iron produced in the blast furnace is desulfurized in a first step, to a range of less than 0.010 percent by mass.
• the pig iron is blown into steel using an LD converter with a capacity of up to 2501.
• Purity purge with an inert gas In contrast to the prior art, this method does not use a ladle oven.
• the setting of the temperature balance in the sense of maintaining the specified casting temperature is guaranteed by a high batch weight with appropriate heat content.
• the casting is then carried out in a round format to a diameter of 220 mm on a multi-strand continuous sheet caster.
• the casting speed is approximately 1.4 m / min.
• the distributor is provided with partitions for better flow control and the immersion spout preferably has a diameter ⁇ 25 mm with a longer pouring funnel that always remains filled.
• the entire casting chamber is sealed with argon and the melt is not flushed with argon during pouring, so that no perm plug is required.
• the hollow body is pushed through several scaffolds by means of an inserted rod and thereby lengthened to a size of 127.5 x 8.25 mm.
• the aspect ratio is 6.18.
• the rod is pulled out and the bottom area is separated.
• the previously described forming takes place in a heat.
• the cooled intermediate tube To be able to carry out stretch-reducing mill, the cooled intermediate tube must be reheated to the forming temperature.
• the final finished dimension of 60.3 D x 8.0 mm wall with an extension of 2.35 is produced without an internal tool.
• the cooling in air takes place on a conventional cooling bed.
• the hot-produced pipe thus produced is then, after soft annealing, the input material for the subsequent cold forming operations, such as cold crawls or cold drawing. Rings are cut from these cold-machined tubes in automatic lathes and the final contour of the rolling bearing is machined.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Forging (AREA)
• Heat Treatment Of Steel (AREA)
• Shaping Of Tube Ends By Bending Or Straightening (AREA)
• Rolls And Other Rotary Bodies (AREA)
• Extrusion Of Metal (AREA)
• Continuous Casting (AREA)
• Cleaning And De-Greasing Of Metallic Materials By Chemical Methods (AREA)
• Heat Treatment Of Articles (AREA)
• Treatment Of Steel In Its Molten State (AREA)
• Metal Rolling (AREA)

Priority Applications (8)

Applications Claiming Priority (4)

Publications (1)

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Family Applications (1)

Country Status (11)

Cited By (2)

Families Citing this family (5)

Citations (4)

• 1995
  • 1995-06-13 CZ CZ963644A patent/CZ364496A3/cs unknown
  • 1995-06-13 PL PL95317837A patent/PL178838B1/pl unknown
  • 1995-06-13 SK SK1597-96A patent/SK282573B6/sk unknown
  • 1995-06-13 CA CA002192970A patent/CA2192970A1/en not_active Abandoned
  • 1995-06-13 ES ES95921715T patent/ES2128736T3/es not_active Expired - Lifetime
  • 1995-06-13 AT AT95921715T patent/ATE176411T1/de not_active IP Right Cessation
  • 1995-06-13 BR BR9508017A patent/BR9508017A/pt not_active IP Right Cessation
  • 1995-06-13 EP EP95921715A patent/EP0764063B1/de not_active Expired - Lifetime
  • 1995-06-13 WO PCT/DE1995/000800 patent/WO1995034387A1/de not_active Ceased
  • 1995-06-13 CN CN95193596A patent/CN1062785C/zh not_active Expired - Fee Related
  • 1995-06-13 JP JP8501479A patent/JPH10505789A/ja active Pending

Patent Citations (4)

Non-Patent Citations (4)

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