US20210078058A1 - Stretch-reducing mill having improved diameter tolerance and wall thickness tolerance - Google Patents

Stretch-reducing mill having improved diameter tolerance and wall thickness tolerance Download PDF

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Publication number
US20210078058A1
US20210078058A1 US17/054,641 US201917054641A US2021078058A1 US 20210078058 A1 US20210078058 A1 US 20210078058A1 US 201917054641 A US201917054641 A US 201917054641A US 2021078058 A1 US2021078058 A1 US 2021078058A1
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United States
Prior art keywords
group
stretch
roll stands
reducing mill
rolls
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Abandoned
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US17/054,641
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English (en)
Inventor
Norbert Theelen
Susanne Zeller
Helge DAEHNDEL
Alexander Gohr
Peter Thieven
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SMS Group GmbH
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SMS Group GmbH
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Filing date
Publication date
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Publication of US20210078058A1 publication Critical patent/US20210078058A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
    • B21B17/14—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling without mandrel, e.g. stretch-reducing mills
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B31/00—Rolling stand structures; Mounting, adjusting, or interchanging rolls, roll mountings, or stand frames
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B2267/00—Roll parameters
    • B21B2267/18—Roll crown; roll profile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B27/00—Rolls, roll alloys or roll fabrication; Lubricating, cooling or heating rolls while in use
    • B21B27/02—Shape or construction of rolls
    • B21B27/024—Rolls for bars, rods, rounds, tubes, wire or the like

Definitions

  • the invention relates to a stretch-reducing mill for the production of seamless tubes, which has a plurality of roll stands arranged one behind the other in a conveying direction of the tubes, each with three rolls arranged at an angular distance of 120°.
  • stretch-reducing and/or sizing mills which have several rolling stands arranged one behind the other in the conveying direction of the tube.
  • the roll stands usually have three rolls which are arranged symmetrically about the pipe at an angular distance of 120°.
  • WO 2017/068533 A1 describes a rolling mill with a first section, which has several roll stands and is set up for rolling via a mandrel introduced into the tube, and a second section, which has several roll stands and is set up for rolling without a mandrel.
  • the roll stands each have three rolls.
  • the axes of rotation of the rolls of adjacent roll stands are each tilted by 180°, as shown in FIGS. 1A and 1B of WO 2017/068533 A1. This corresponds to an offset by the above-mentioned 60°.
  • the inside of the pipe is unevenly formed in the stretch-reducing mill due to the uneven speed distribution between the caliber base and the caliber jump of the rolls.
  • a polygon-like internal cross-section is formed perpendicular to the pipe axis. This phenomenon is also known as “inner polygon formation”.
  • the rolling mill functions as an extraction mill, additional complications result from temperature differences from the preceding stretching unit, which also cause different forming conditions between the caliber base and the caliber jump. This is superimposed on the inner polygon formation of the following aggregate and can thus intensify the effect.
  • the internal polygon formation is particularly pronounced when both the stretching unit and the extraction mill have a three-roller configuration.
  • a four-roller design as an alternative is mostly out of the question due to the limited installation space for the roller bearings and the associated low capacity to absorb the forming forces.
  • An object of the invention is to improve the rolling quality of a stretch-reducing mill for the production of seamless tubes, in particular to equalize the rolled wall thicknesses.
  • the stretch-reducing mill according to the invention is used to produce seamless tubes, preferably from a metal material.
  • the term “stretch-reducing mill” is to be understood here as a generic term for rolling mills which bring about both a reduction in the outside diameter of the tube and a reduction in the inside diameter, resulting in elongation of the tube.
  • the stretch-reducing mill is preferably a mandrel-less mill.
  • the wall thickness of the pipe can also be increased or decreased to a certain extent.
  • the stretch-reducing mill has a plurality of roll stands arranged one behind the other in the conveying direction of the pipes, each with three rolls arranged at an angular distance of 120°.
  • the rollers are thus arranged symmetrically about the pipe in order to exert a rolling force on the outer circumference of the pipe from three sides.
  • the roll stands are subdivided into at least two groups, each with at least two roll stands, the rolls of adjacent roll stands within a group being inclined relative to one another at a group internal angle. Furthermore, the rolls of roll stands of adjacent groups are inclined relative to one another at a group angle that is smaller than the group internal angle.
  • the term inclined includes a relative rotation of adjacent roll stands (analogous to groups)—more precisely, their rollers—by the said group-internal angle (analogous to group angles).
  • the rollers are arranged symmetrically at an angular distance of 120° about the pipe, a state which corresponds to a rotation by a certain angle can also be achieved by rotation by one or more other angles.
  • an inclination of 60° can also be achieved by tilting by 180°.
  • the term “inclined” at an angle is used herein to denote a rotation by that angle as well as all equivalent angles.
  • the rotation can take place both clockwise and counterclockwise in relation to the rolling direction.
  • the rolling stands are inclined in a group-related manner by a group angle which is smaller than the group-internal angle. Due to such an inclination, the inner polygon formation of a group is superimposed with an inner polygon formation of the following group inclined by the group angle. This improves approximation to a circular inner cross-section of the pipe.
  • Another technical effect is that the group-wise angular offset of the rollers improves the temperature equalization in the pipe, provided there is a temperature gradient along the radial direction of the pipe. Both effects contribute to the equalization of the rolled wall thicknesses and thus to the improvement of the rolling quality when rolling seamless tubes.
  • the group-internal angle is preferably 60°, which results in sections of the tube being alternately rolled in the groove base or from the groove jump. This improves the wall thickness characteristics within the group.
  • the group angle is preferably 30°. Due to such an inclination, the inner polygon formation of a first group is superimposed with an inner polygon formation inclined by 30° in a subsequent second group. A dodecahedron-shaped inner polygon is generated whose deviations between a maximum wall thickness and a minimum wall thickness are significantly reduced compared to a hexagonal polygon.
  • the number of rolls per caliber can in principle differ from “three”; in particular, four rolls per caliber are possible, even if this tends to be the exception in practice.
  • the rolls of the group-related roll stands preferably have a caliber shape that deviates from the circular shape. This allows preventing material from entering the gap between the rolls, which may damage the surface of the rolling stock.
  • At least one neutral roll stand with three rolls each arranged at an angular distance of 120°, the shape of which counteracts a torsional moment acting on the pipe.
  • the neutral roll stand thus serves preventing the pipe from twisting between two adjacent groups.
  • the cause of potential twisting of the tube is that, especially in the case of non-circular calibres, a torsional moment can act on the tube about its own axis if a group-related inclination is used.
  • at least one neutral roll stand is preferably connected between adjacent groups.
  • a neutral roll stand can be characterized, for example, in that its caliber shape deviates less from the circular shape than that of the other stands and/or the decrease in diameter is reduced relative to the other stands.
  • the rolls of the one or more neutral roll stands preferably have a circular or approximately circular caliber shape.
  • the one or more neutral roll stands preferably do not form (an) independent group(s), rather they are preferably completely or at least partially a structural component of the groups defined above, for example the group located upstream in the conveying direction. If not all of the neutral roll stands belonging to the transition between two groups are part of the group located upstream, the remaining neutral roll stands are structurally preferably part of the group located downstream. In this way, a special structural solution can be avoided.
  • the size of the groups i.e., the number of roll stands in the respective group, can be made dependent on the dimensions to be rolled. Thus preferably about 35% to 70% of the total diameter reduction takes place in the first group and the remaining diameter reduction in the second group.
  • the reason for this distribution is that the inner polygon formation gradually builds up and thus there is a risk of overcompensation. In other words, in the case of an unfavorable distribution, the optimal compensation is not behind the last roll stand, but on an inner roll stand.
  • the stretch-reducing mill is preferably an extraction mill.
  • An extraction mill means a mill that is located downstream of a stretching mill with a mandrel, in order to pull the pipe off the mandrel after having been rolled by the mandrel. Extracting mills are increasingly designed so that, in addition to the simple separation of the pipe from the mandrel, they also cause a comparatively strong deformation of the pipe. In this process stage, the pipe has a comparatively strong temperature gradient from the outside (cold) to the inside (warm). If the extraction mill is designed as a stretch-reducing mill, the inhomogeneous temperature distribution in the tube can have a particularly detrimental effect on the rolling result. For this reason, a group-related inclination is particularly suitable for an extraction mill designed as a stretch-reducing mill.
  • FIG. 1 is a schematic view of a stretch-reducing mill with grouped rolling stands.
  • FIG. 2 shows a rolling stand in three-roll design.
  • FIG. 3 shows schematically a group-wise inclination of roll stands.
  • FIG. 1 is a schematic view of a stretch-reducing mill 1 .
  • the stretch-reducing mill 1 has a plurality, here fifteen, roll stands 10 .
  • the roll stands 10 can preferably be controlled individually. In particular, the speeds of the rolls 11 (see FIG. 2 ) of the roll stands 10 can be set individually.
  • the rolling stands 10 are controlled via a control device 2 , preferably computer-based.
  • the control device 2 takes over the control of further components of the stretch-reducing mill 1 if necessary.
  • control device includes both centralized and decentralized structures for controlling the stretch-reducing mill 1 .
  • the control device 2 therefore does not have to be located at the “location” of the stretch-reducing mill 1 or be part of it.
  • control tasks, data processing steps, etc. can be distributed to different computing devices, which then fall under the term “control device” in their entirety.
  • the communication of the control device 2 with the components to be controlled can take place both physically via cable as well as wirelessly.
  • the pipe runs in a conveying direction F through the stretch-reducing mill 1 .
  • the pipe R Before entering the stretch-reducing mill 1 , the pipe R has an inlet-side wall thickness d 1 .
  • the pipe R has a wall thickness d 2 and a reduced diameter.
  • the wall thickness d 2 is not necessarily reduced compared to the wall thickness d 1 ; rather, depending on the roll speed, it can be smaller, the same, but also larger than the initial wall thickness d 1 .
  • the inlet-side and/or outlet-side wall thickness d 1 or d 2 can be measured by means of one or more wall thickness measuring devices (not shown).
  • further process parameters can be measured or otherwise determined, for example the inlet-side and/or outlet-side speed of the pipe R, the inlet-side and/or outlet-side weight of the pipe R, etc.
  • the determined process parameters can be transmitted to the control device 2 to control the rolling process.
  • FIG. 2 shows a roll stand 10 , 10 ′ with three rolls 11 arranged symmetrically about the pipe R at an angular distance of 120°.
  • the rolls 11 each have an arcuate cross section of the roll surface, i.e., a round caliber shape.
  • the caliber base 13 refers to the center of the roll surface, viewed in the cross section of FIG. 2 and in the axial direction of the corresponding roll 11 .
  • the caliber base 13 and the caliber jump 14 are characteristic positions of the roll surface.
  • the shape of the caliber preferably deviates from a perfect circular arc.
  • the reason for the deviation from the circular shape is that in this way material can be prevented from entering the gap between adjacent rolls 11 —more precisely, between the caliber jumps 14 of adjacent rolls 11 .
  • Local caliber size reduction and local caliber size increase allows compensation of deviations in the pipe diameter.
  • the roll stands 10 are divided into two groups A and B, each of which has seven roll stands 10 .
  • the groups A, B are disjoint, i.e., they are arranged sequentially one behind the other and do not overlap or interpenetrate.
  • the rolls 11 of the roll stands 10 are inclined relative to one another by an internal group angle ai of 60° or approximately 60°, so that the tube sections are alternately rolled in the caliber base 13 or in the caliber jump 14 .
  • the number of roll stands 10 per group A, B is selected so as to minimize the formation of the inner polygon.
  • the number of roll stands 10 per group A, B is at least two; preferably in the range from 2 to 8.
  • the number of roll stands 10 can vary from group A to group B.
  • OG is equal to or about 30°.
  • the inner polygon formation of a group A is superimposed with an inner polygon formation inclined by OG of the following group B.
  • an inner dodecahedron is generated, which deviates between a maximum wall thickness and a minimum wall thickness significantly less compared to an inner hexagon.
  • the internal geometry of the pipe R is thus approximated to an ideal round.
  • the group-related rotation or inclination described above is shown schematically in FIG. 3 .
  • the roll stands 10 of groups A, B are shown schematically in FIG. 3 .
  • the roll stands 10 or their rolls 11 are alternately rotated or tilted by 180°, whereby the above-described inclination of 60° is achieved.
  • a rotation of 90° was made between groups A and B, resulting in an inclination of 30°.
  • the two types of inclination can also be achieved directly by rotating about the group angle OG and the group-internal angle ai.
  • the variant shown in FIG. 3 has structural advantages, in particular when coupling the rolls 11 to the drives (not shown).
  • the offset of 60° results, for example, by tilting the roll stands 10 by 180°.
  • the drives can be arranged on the usual feed-in side and opposite the feed-in side with internal power distribution. This simplifies the installation and maintenance of the drives, since the coupling can take place directly when the scaffolding is pushed in.
  • the size of the groups A, B i.e., the number of roll stands 10 in the respective group A, B, can be made dependent on the dimension to be rolled. Thus, preferably about 35% to 70% of the total diameter reduction takes place in the first group A and the remaining diameter reduction in the second group B.
  • the reason for this distribution is that the inner polygon formation gradually increases and thus there is a risk of overcompensation. In other words, in the case of an unfavorable distribution, the optimal compensation is not downstream of the last roll stand 10 , but on an inner roll stand 10 .
  • FIGS. 1 and 4 also show a roll stand 10 ′, which is referred to herein as a “transition pass” or “neutral roll stand”.
  • the neutral roll stand 10 ′ serves to avoid twisting of the pipe R between groups A and B.
  • the cause of any twisting of the pipe R is that in the case of non-circular deformation, a torsional moment can act on the pipe R about its own axis if a group-related inclination of OG is applied.
  • at least one neutral roll stand 10 ′ is preferably connected between groups A, B.
  • the caliber shape of the rolls 11 of the neutral roll stand 10 ′ is thus determined so as to counteract the tendency to torsion.
  • the rolls 11 of the neutral roll stand 10 ′ preferably have a circular or approximately circular caliber shape, as shown in FIG. 2 .
  • the caliber base 13 which is offset in groups, improves temperature compensation in the event of a temperature gradient in the pipe R.
  • This effect particularly comes to bear in the case of inhomogeneous temperature distribution along the radial direction of the tube R, as is the case in particular in extraction mills. Extracting mills, which are normally located immediately downstream of a stretching mill with a mandrel, serve to separate the tube R from the mandrel. In this process stage, the tube R has a comparatively strong temperature gradient from the outside (cold) to the inside (warm).
  • the extraction mill is designed as a stretch reducing mill 1 , i.e., in addition to the separation of mandrel and tube R, it is also designed for strong deformation of the tube R, the inhomogeneous temperature distribution in the tube R can have a detrimental effect on the rolling result.
  • a group-related inclination according to the disclosed exemplary embodiments is particularly suitable for an extraction mill, in particular an extraction rolling mill designed as a stretch-reducing mill 1 .

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Reduction Rolling/Reduction Stand/Operation Of Reduction Machine (AREA)
  • Metal Rolling (AREA)
  • Control Of Metal Rolling (AREA)
US17/054,641 2018-05-18 2019-05-08 Stretch-reducing mill having improved diameter tolerance and wall thickness tolerance Abandoned US20210078058A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102018207908.0A DE102018207908A1 (de) 2018-05-18 2018-05-18 Streckreduzierungswalzwerk mit verbesserter Durchmesser- und Wanddickentoleranz
DE102018207908.0 2018-05-18
PCT/EP2019/061761 WO2019219463A1 (de) 2018-05-18 2019-05-08 Streckreduzierungswalzwerk mit verbesserter durchmesser- und wanddickentoleranz

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US20210078058A1 true US20210078058A1 (en) 2021-03-18

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US (1) US20210078058A1 (de)
EP (1) EP3793755B1 (de)
CN (1) CN112135696A (de)
AR (1) AR114907A1 (de)
DE (1) DE102018207908A1 (de)
RU (1) RU2751408C1 (de)
WO (1) WO2019219463A1 (de)

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CN113688501B (zh) * 2021-07-16 2022-04-15 北京科技大学 一种兼顾多种宽度板带轧制的变接触支持辊辊形设计方法

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US20100132425A1 (en) * 2006-11-09 2010-06-03 Kenichi Sasaki Mandrel mill, operating method of the same and production method of seamless pipe
CN101773937A (zh) * 2009-12-23 2010-07-14 太原通泽重工有限公司 分组三辊定减径机
CN105363782A (zh) * 2015-11-30 2016-03-02 太原科技大学 张力减径机工作机组轧辊孔型

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DE102018207908A1 (de) 2019-11-21
EP3793755B1 (de) 2023-07-26
CN112135696A (zh) 2020-12-25
AR114907A1 (es) 2020-10-28
RU2751408C1 (ru) 2021-07-13
WO2019219463A1 (de) 2019-11-21
EP3793755A1 (de) 2021-03-24

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