Classifications

• • 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
  • B21B17/02—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length
  • B21B17/04—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length in a continuous process
• • 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
• • 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

Definitions

• the present invention relates to a drawing and rolling method using a mandrel mill. Specifically, the present invention relates to a stretching method using a mandrel mill that can effectively prevent the occurrence of both overfill and underfill in stretching rolling using a mandrel mill.
• this mandrel mill a two-roll mandrel mill having a pair of perforated rolling rolls arranged so that the rolling direction is alternately shifted by 90 ° between adjacent stands has been frequently used.
• a four-roll mandrel mill equipped with four perforated rolling rolls in which the angle formed by the two adjacent stands in the rolling direction is 90 ° has come to be used.
• a three-roll mandrel mill is also proposed that includes three perforated rolling rolls in which the rolling directions of two adjacent stands are alternately shifted by 60 ° and the angle formed by the rolling down is 120 °. .
• Patent Document 1 the ratio (the hot finish circumference of the perforated circumference Z-mill outlet steel pipe) when a base pipe mainly made of alloy steel such as stainless steel is drawn and rolled by a mandrel mill,
• the ratio should be 1.12 or more
• for the second stand 1.06 or more
• for the third stand 1.02 or more to secure the outer circumference of the raw tube on the exit side of the mandrel mill.
• An invention is disclosed in which underfill is prevented from occurring by forming an appropriate gap between the mandrel bar and the blank at the end of the blank where the underfill is most likely to occur.
• Patent Document 2 mainly describes a mandrel including a 13% Cr steel and the like (including unless otherwise specified, "%" in terms of composition means “% by mass”).
• An invention is disclosed in which the occurrence of underfill at the pipe end portion of the raw pipe is prevented by setting within a predetermined range.
• Patent Document 1 Japanese Patent No. 2582705
• Patent Document 2 Japanese Patent Laid-Open No. 2003-10907
• Patent Document 1 prescribes appropriate conditions for a raw pipe made of an alloy steel such as stainless steel having a specific dimension. There was something to do. That is, based on the perforation circumference disclosed in Patent Document 1, the outer diameter of the raw pipe, etc., the ratio of the wall thickness to the outer diameter using a raw pipe made of ordinary steel with a Cr content of less than 1% ( Overfilling occurs when trying to stretch and roll a thin-walled tube (thickness-to-outer diameter ratio) of 3% or less.
• a perforated rolling roll is used in the case of drawing and rolling an alloy steel or a thin-walled tube having a normal steel strength with a wall thickness outer diameter ratio of 3% or less. It must be replaced.
• the perforated rolling roll of the constant diameter rolling mill is replaced for each outer diameter setup, but in order to implement the invention disclosed in Patent Document 1, the hole in the constant diameter rolling mill is used.
• the mandrel mill In addition to replacing the die rolling roll, the mandrel mill must be stopped and the punch rolling roll replaced whenever the steel grade to be rolled is changed.
• the seamless pipes made of ordinary steel and alloy steel must be manufactured separately, even with the same outer diameter setup.
• the replacement time of the perforated rolling roll in the constant diameter rolling mill is doubled.
• Patent Document 2 also shows appropriate conditions specialized for a raw pipe made of alloy steel such as 13% Cr steel having a specific dimension. There is a problem similar to that of the invention.
• the present invention has been made in view of the problems of the prior art, and uses a common combination of perforated rolling rolls for various steel types, such as ordinary steel and alloy steel, and thick pipes.
• Another object of the present invention is to provide a stretch rolling method using a mandrel mill that can effectively prevent the occurrence of overfill and underfill.
• the present invention is a method for performing elongation rolling of a raw pipe using a holo-shell as a raw material using a mandrel mill including a plurality of stands provided with a plurality of perforated rolling rolls, the Cr content of the raw pipe Is 10% or more, the outer diameter of the holo shell is such that the ratio (the outer perimeter of the holo shell Z, the finish perimeter of the tube at the exit of the finishing stand) is 1.1 or greater. On the other hand, if the Cr content in the tube is less than 10%, the outer diameter of the hollow shell is set so that this ratio is less than 1.1, and the first stand of the mandrel mill is set.
• the first stand and the second stand It is a drawing and rolling method using a mandrel mill characterized in that a hole profile of each hole rolling roll provided is set.
• one kind of perforated rolling roll is used for various steel types such as ordinary steel and alloy steel and thick pipes without changing the combination of perforated rolling rolls according to the steel type and the like.
• both overfill and underfill can be effectively prevented.
• Fig. 1 is a graph showing a model of the behavior when an elemental pipe made of alloy steel is drawn and rolled
• Fig. 1 (b) is a diagram based on the conventional technology
• Figure 1 (c) shows a model of the behavior when a pipe made of alloy steel is stretch-rolled with the perforation circumference of the die rolling roll set large
• 3 is a graph showing a model of behavior when a tube is drawn and rolled.
• the axial strain which is the horizontal axis of the graphs shown in FIGS. 1 (a) to 1 (c), is ln (the length of the tube after drawing and rolling Z the length of the tube before drawing and rolling).
• Fig. 2 shows the tube from the entrance side to the exit side of the stand when it is stretch-rolled under the same conditions as in Fig. 1 (a) except that the outer diameter of the tube is set to 102mm. It is a graph which shows the fluctuation
• FIG. 3 is an explanatory diagram for explaining the definition of the perforated circumference
• FIG. 3 (a) schematically shows a part of a perforated rolling roll provided in a two-roll mandrel mill.
• FIG. 4 is a graph showing an example of the results of a stretch rolling test.
• FIG. 5 is a graph showing an example of the results of a stretch rolling test.
• FIG. 6 is a table showing the results of Examples and Comparative Examples of a drawing and rolling method using a mandrel mill according to the present invention.
• Fig. 1 (a) is a graph showing a model of the behavior when an elemental tube made of alloy steel is stretch-rolled
• Fig. 1 (b) is a diagram of a hole in a perforated rolling roll based on the conventional technology.
• Fig. 1 (c) is a graph showing a behavior model when a pipe made of alloy steel is stretch-rolled in a state where the mold perimeter is set large
• Fig. 1 (c) shows a case where a pipe with ordinary steel strength is drawn and rolled. It is a graph which shows the model of the behavior of.
• the axial strain which is the horizontal axis of the graphs shown in Fig. 1 (a) to Fig. 1 (c), is In (the length of the tube after elongation rolling Z the length of the tube before elongation rolling).
• the graph shown in Fig. 1 (a) shows a hollow shell made of alloy steel having an outer diameter of 100 mm on a stand provided with a perforated rolling roll having a perforated circumference corresponding to an inner diameter of 98 mm (broken line in the figure).
• the figure shows the fluctuations in the outer diameter and axial strain of the raw tube from the entrance side to the exit side when the stand is drawn and rolled until the axial strain at the exit side of this stand reaches 0.3.
• the outer diameter of the pipe at the outlet side (axial strain 0.3) is Underfill occurs because it is approximately 96 mm and is approximately equal to the above-mentioned added value.
• the graph shown in Fig. 1 (b) is the exception that the perforation length of the perforated rolling roll is set to a perforation perimeter corresponding to the inner diameter of 99 mm shown by the broken line in the figure, according to the prior art.
• the graph shown in Fig. 1 (a) shows the fluctuation in the direction of the arrow in the figure, and the outer diameter of the bare tube on the exit side of the stand (axial strain 0.3) is approximately 97 mm. Therefore, since there is a sufficient margin for the above-mentioned added value (96 mm), underfill can be prevented.
• the graph shown in Fig. 1 (c) is the same as that in Fig. 1 (a) except that the base tube is made of ordinary steel.
• the fluctuations in the outer diameter and axial strain of the tube up to the side are shown.
• the outer diameter of the bare tube on the exit side of the stand (axial strain 0.3) is approximately 97.5 mm. Therefore, there is enough room for the above-mentioned added value (96mm), so there is no underfill! /.
• Fig. 2 shows the condition of the tube from the entrance side to the exit side of the stand when it is stretch-rolled under the same conditions as in Fig. 1 (a), except that the outer diameter of the tube is set to 102 mm. It is a graph which shows the fluctuation
• Fig. 1 (a) shows the behavioral model of the alloy steel shown in Fig. 1 (a)
• Fig. 1 (b) it is not possible to set the hole perimeter of the hollow tube roll as a large pipe. Underfill can also be prevented by increasing the outer diameter of the tube as in the model shown in Fig. 2.
• the present invention has been made based on the fact that underfill can be prevented by increasing the outer diameter of the hollow shell as shown in the graph of FIG. In the model shown in Fig. 2, there is no need to change the perimeter of the perforated rolling roll. Overfilling can be prevented with the perforated rolling roll having the same mold circumference.
• the outer diameter of the holo-shell that is stretch-rolled by the mandrel mill is appropriately changed for each steel type and size using, for example, a setting change of a drilling machine or a shell sizer, an alloy steel
• a combination of one type of punching roll can be set.
• the graphs showing the rolling behavior models in FIGS. 1 and 2 are plotted based on the concept described below.
• the deformation process of the blank tube is performed until the outer peripheral surface of the blank tube starts to contact the perforated rolling roll and the force is reduced with the mandrel bar (the outer diameter of the blank tube becomes equal to the inner diameter of the perforated rolling roll). )) And the “thickening process” that is squeezed between the perforated rolling roll and the mandrel bar.
• the graph represented by line segment A1B1 shown in Fig. 1 (a) corresponds to the behavior in the outer diameter machining process, and is simply constrained by the hole profile of the hole roll regardless of the steel type. In addition, the outer diameter of the tube, that is, the outer peripheral length is reduced.
• the graph represented by line segment A2B2 in FIG. 1 (b), the graph represented by line segment A3B3 in FIG. 1 (c), and the graph represented by line segment A4B4 in FIG. Corresponds to the behavior in the diameter machining process. As described above, the behavior in the outer diameter machining process does not depend on the steel type, so all graphs are plotted with the same gradient.
• the graph represented by the line segment BlCl in FIG. 1 (a) corresponds to the behavior in the thickness-cage process, and the raw tube is not restrained by the hole profile of the hole roll.
• the outer diameter that is, the outer peripheral length is reduced because tensile deformation occurs as the stretching increases and the tube extends.
• the graph represented by line B2C2 in FIG. 1 (b), the graph represented by line B3C3 in FIG. 1 (c), and the graph represented by line B4C4 in FIG. Corresponds to the behavior in the thick caking process.
• the present invention has been completed by specifying various parameters relating to the drawing and rolling conditions as the above-described equations (1) to (3) using such a principle.
• the present invention is not limited to application to a two-roll mandrel mill, and is similarly applied to a three-roll or four-roll mandrel mill.
• the “finishing perimeter” means the outer perimeter of the raw tube on the exit side of the finishing stand.
• Fig. 3 is an explanatory diagram for explaining the definition of the perforated circumference
• Fig. 3 (a) is a longitudinal sectional view schematically showing a part of a perforated rolling roll provided in a two-roll type mandrel mill.
• FIG. 3 (b) is a longitudinal sectional view schematically showing a part of a perforated rolling roll provided in a three-roll mandrel mill.
• the hole profile 1 of the hole roll 1 provided in the mandrel mill is generally formed by combining three arcs, the groove bottom B and the hole center.
• a straight line connecting O is a symmetrical curve, and the profile force radius on one side is R1
• the shape is a continuous combination of an arc with a central angle al, an arc with a radius R2 and a central angle a 2 (hereinafter referred to as an arc R2), and an arc with a radius R3 and a central angle a 3 (hereinafter referred to as an arc R3). It is.
• the center angle at radius R4 is perpendicular to straight line L that is in contact with the contact point between arc R2 and arc R3, and forms an angle of 90 ° with the straight line connecting groove bottom B and hole center O.
• the perimeter of the hole type is determined as 4 (Rla1 + R2a2 + R4a4).
• the hole profile P of the hole-rolling roll 1 provided in the three-roll mandrel mill is the same as that of the two-roll mandrel mill described above.
• the shape is a combination of three arcs Rl, R2 and R3.
• the perimeter of the hole type is defined as 6 (Rl al + R2 a 2 + R4 a 4).
• the definition of the perforation circumference is generalized for the number of various perforated rolling rolls as follows.
• the perimeter of the hole is defined as 2n (Rl al + R2 a 2 + R4 a 4).
• the hole profile P force of the hole-rolling roll 1 is projected outward (toward the direction opposite to the hole center O) with two convex arcs R1, R2,
• the shape is a continuous combination of one convex arc R3 (toward the hole center O).
• the present invention is not limited to this.
• the arc that is convex toward the inside may be a shape in which a plurality of arcs having different radii are continuously combined.
• the hole circumference is Defined as 2n (L0 + R4 a 4)
• the perimeter of the third stand determined by the plurality of perforated rolling rolls provided on the third stand of the mandrel mill is as follows: It is possible to set the hole profile of the hole-type rolling roll provided in the third stand so that the hole perimeters of the second stand and the third stand satisfy the following expression (5). desirable.
• the finishing perimeter means the perimeter of the blank at the end of drawing and rolling.
• FIG. 4 is a graph showing an example of the results of the stretch rolling test.
• “X” indicates a tube with underfill or overfill
• “ ⁇ ” indicates a tube with no underfill or overfill.
• the ratio of the first stand is assured for the stainless steel tube. If the (perforated circumference Z finish circumference) is less than 1.06, underfill occurs in the second stand, and the ratio of the second stand (hole circumference Z finish circumference) is less than 1.05. Underfill occurs at the 3rd stand. On the other hand, if the ratio of the first stand (perforated circumference Z finish circumference) is greater than 1.12, the thin steel tube made of ordinary steel will cause overfill in the second stand, and the ratio of the second stand (hole If the mold perimeter (Z finish perimeter) is greater than 1.10, overfill occurs at the third stand.
• the ratio (peripheral length of the holo-shell Z is the outer circumference length of the blank tube on the exit side of the finishing stand.
• the outer diameter of the holo-shell is set so that a certain finish circumference is 1.1 or more.
• the ratio (the outer-periphery length of the holo-shell Z By setting the outer diameter of the hollow shell so that the outer circumference of the blank tube on the exit side of the finishing stand is less than 1.1, the outer diameter of the hollow shell is limited to Cr as long as the predetermined condition is satisfied. It can be seen that rolling is possible with a combination of one type of perforated rolling roll without changing the combination depending on the content.
• the outer diameter of the hollow shell can be appropriately adjusted by a known method disclosed in, for example, Japanese Patent Laid-Open Nos. 8-71615 and 2002-1 1507.
• underfill and overfill are particularly likely to occur, and in the second and third stands, underfill and overfill are combined with a single type of perforated rolling roll. Force that can effectively prevent overfill
• the rolling test was conducted by changing the ratio of the third stand (perforated circumference Z finishing circumference) to various values.
• FIG. 5 is a graph showing an example of the results of this rolling test.
• “X” indicates a tube that has underfilled or overfilled
• “ ⁇ ” indicates a tube that has a tendency to underfill or overfill
• “ ⁇ ” indicates underfill and overfill. Indicates a tube where no overfill has occurred.
• the 4th stand will tend to underfill slightly, and the thin-walled tube with normal steel strength will have a ratio of the 3rd stand (perforated circumference Z finish circumference). If it is larger than 1.07, the 4th stand tends to overfill. Also, if the hole circumference of the second stand ⁇ the hole circumference of the third stand, the outer circumference of the blank tube cannot be adjusted in the third stand, so underfill and overfill are likely to occur. Overfill may occur at the 4th stand.
• the perimeter of the third stand determined by the plurality of perforated rolling rolls provided in the third stand is expressed by equation (4): 1.02 ⁇ 3 Stand hole perimeter Z Finish perimeter ⁇ 1.07, 2nd stand and 3rd stand perimeter (5) formula: 2nd stand perimeter> 3rd stand perimeter It can be seen that it is preferable to set the perforated profile of the perforated rolling roll provided on the third stand so as to satisfy the respective lengths.
• the perforated peripheries S1 to S3 of the first to third stands set for each condition are as shown in the table of FIG. 6, and Examples 1 to 14 and Examples 2-1 and 2 — 2, Example 3-1 and 3-2 were respectively set to the same perforation circumference (using the same combination of perforated rolling rolls) ) o
• the numerical values shown in the column “Hollow shell Z after drawing and stretching” are the values of the holo shell outer peripheral length Z finish peripheral length.
• the rolling test was carried out under the same conditions as in the Examples, except that the values of the outer perimeter length of the hollow shell Z and the perimeter lengths Sl to S3 of the first to third stands were changed variously.
• a hollow shell with an outer diameter of 300 mm, a thickness of 20 mm, and a length of 6000 mm is rolled by a 5-roll mandrel mill consisting of 5 stands, and the outer diameter is 27 0 (finishing length) on the exit side of the mandrel mill.
• 270 X ⁇ ) ⁇ , 10 mm thick tube was tested (Comparative Examples 1–1, 1–4, 2–1, 2–4, 3–2, 3–3, 3–4, 4 — 2, 5— 2).
• Comparative Examples 1 to 1 to 14 Comparative Examples 2 to 1 to 2-4, Comparison Examples 3-1 to 3-4, Comparative examples 4-1 and 4-2, and Comparative examples 5-1 and 5-2 are set to the same perforation circumference, and the same perforation roll combination Using.
• the comparative examples include at least one of a tube with a Cr content of 10% or more (13% Cr steel) or a tube with a Cr content of less than 10% (9% Cr steel, 5% Cr steel, carbon steel).
• wrinkles occurred at a rate exceeding 4%.
• the present invention example includes a raw pipe having a Cr content of 10% or more (13% Cr steel) and a raw pipe having a Cr content of less than 10% (9% Cr steel, 5% Cr steel, carbon steel). In either case, almost no wrinkles were generated even though rolling was performed using the same combination of perforated rolling rolls.

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• 2005
  • 2005-03-28 JP JP2005090432A patent/JP4441912B2/ja active Active
• 2006
  • 2006-03-28 BR BRPI0609266-7A patent/BRPI0609266B1/pt active IP Right Grant
  • 2006-03-28 RU RU2007139816/02A patent/RU2357815C1/ru not_active IP Right Cessation
  • 2006-03-28 CN CN2006800104930A patent/CN101151107B/zh not_active Expired - Fee Related
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