JP2013230500A - Roll stand, and three-roll reducing mill mounting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll stand of an internal-gear one-shaft driving type, which can prevent occurrence of a thickness deviation in an metal pipe obtained in three-roll reduction rolling, and does not require reconstruction of the periphery of the stand.SOLUTION: A roll stand 1 includes an input shaft 6 coupled with a power shaft 11 of a reducing mill. In the roll stand, each of roll shafts 3a, 3b, and 3c of three grooved rolls 2a, 2b, and 2c is arranged to be tilted to the input shaft 6, and a mechanism of power transmission composed of a gear group of external gears 8a, 8b, 8c, and 8d and bevel gears 9a and 9b is provided to transmit a power inputted from the power shaft 11 to the input shaft 6, to one roll shaft 3a; in addition, there are provided bevel gears 4a1, 4a2, 4b, and 4c adapted for transmitting the power transmitted to the one roll shaft 3a, to remaining two roll shafts 3b and 3c.

Description

  The present invention is a three-roll drawing mill used in drawing rolling to finish the outer diameter and wall thickness of metal pipes to predetermined dimensions when manufacturing metal pipes such as electric welded steel pipes, forged welded steel pipes, and seamless steel pipes. Hereinafter, it is also simply referred to as a “drawing mill”, and in particular, relates to a roll stand mounted over a plurality of stages along a pass line of the drawing mill, and a drawing mill equipped with the roll stand.

  ERW steel pipes are manufactured by using steel strip as a raw material, and continuously forming the steel strip into a cylindrical shape with a group of forming rolls, and then joining the joints by hot or cold electrical resistance welding. Is done. Forged welded steel pipe is made of steel strip, and the heated steel strip is continuously formed into a cylindrical shape by a group of forming rolls, and then the oxygen is blown to the joint end to increase its temperature instantaneously, Are manufactured by joining together. In that case, those pipes whose ends are joined are finished by drawing with a drawing mill (eg, stretch reducer, sizer) into a metal tube having a predetermined outer diameter and thickness.

  The seamless steel pipe is made of a steel piece having a circular or square cross section, and is manufactured by a hot extrusion pipe manufacturing method typified by the Eugene Sejurne method or a hot rolling pipe manufacturing method typified by the Mannesmann method. For example, in the case of the hot rolling pipe manufacturing method, a heated steel piece is pierced and rolled to form a hollow shell, and then drawn and rolled by a mandrel mill, a plug mill, or the like. At that time, the stretched and rolled raw tube is finished into a metal tube having a predetermined outer diameter and thickness through drawing rolling by a drawing mill.

  FIG. 1 is a diagram schematically showing the overall configuration of a drawing mill. FIG. 2 is a schematic diagram showing a normal arrangement configuration of hole-type rolls in a roll stand mounted on a drawing mill.

  As shown in FIG. 1 and FIG. 2, a three-roll type drawing mill has a roll stand (hereinafter also simply referred to as “stand”) 1 in which three perforated rolls 2 are incorporated in a plurality of stages. Configured. In the case of a stretch reducer, the number of stands 1 mounted on the drawing mill is 10 to 20 and is appropriately determined according to the finished outer diameter. FIG. 2 shows an example in which 16 stands 1 are mounted. Each stand 1 is a first stand (denoted as “# 1” in FIG. 2) and a second stage in order from the entrance side where the metal blank W to be drawn is introduced into the drawing mill. The second stand (referred to as “# 2” in FIG. 2),..., And the last stand (referred to as the 16th stand in FIG. 2 and indicated as “# 16”) as the final stand, respectively. Called.

  As shown in FIG. 2, the three perforated rolls 2 of each stand are arranged at equal intervals of 120 ° around the pass line L (see FIG. 1). Normally, the arrangement of the perforated rolls 2 of the stands adjacent to each other is shifted around the pass line L with a phase angle of 60 °. For this reason, the arrangement of the perforated rolls 2 is alternately switched at each stage along the pass line L with a phase angle of 60 °, and the odd-numbered stands (first stand, third stand,...) They are coincident with each other on the even-numbered stands (second stand, fourth stand,...).

  In the actual operation of drawn rolling, in order to produce metal tubes with various dimensional specifications, the drawn rolling mill is replaced with a stand that incorporates a hole roll of appropriate dimensions according to the finished outer diameter of the produced metal tube. . Here, due to the difference in the structure for rotationally driving the three perforated rolls, the stand is an internal gear single-axis drive type (hereinafter also referred to as “internal gear type”) and an external gear three-axis drive type ( (Hereinafter also referred to as “external gear type”).

  In the internal gear type stand, the rotational drive power is first transmitted to one of the roll shafts of the three hole-type rolls arranged in the housing. The bevel gear indirectly transmits power to the remaining two roll shafts. Thus, one hole-type roll is directly rotated and driven directly, and the remaining two hole-type rolls are driven and rotated in accordance with the rotation drive. In the case of an internal gear type stand, the drawing mill includes one horizontal power shaft for driving the perforated roll at each stage on which the stand is mounted. For this reason, the structure around the stand is simple.

  On the other hand, in the external gear type stand, a gear is not built in the housing, but rotational driving power is transmitted to each of the roll shafts of the three hole type rolls. As a result, the three perforated rolls are individually driven to rotate. In the case of an external gear type stand, the drawing mill is provided with a power shaft for driving a perforated roll separately from each of the three stages on which the stand is mounted. For this reason, the structure inside the stand housing is simple, but the structure around the stand is complicated.

  3 and 4 are schematic views showing the configuration of a normal stand when an internal gear single-axis drive type roll stand is employed. Here, FIG. 3 shows the configuration of the odd-numbered stand (see FIG. 2), and FIG. 4 shows the configuration of the even-numbered stand (see FIG. 2).

  As shown in FIG. 3, in the housing 10 of the odd-numbered stand 1, a hole-type roll (hereinafter also referred to as “driving hole-type roll”) that is rotationally driven is horizontally below the pass line L. A hole-type roll 2a having an extended roll shaft 3a is disposed. On the extended line of the roll shaft (hereinafter also referred to as “drive roll shaft”) 3a of the drive hole type roll 2a, a coupling 5 exposed on one side of the housing 10 and an input shaft 6 connected thereto are arranged. It is installed. The drive roll shaft 3a is firmly connected to the input shaft 6.

  The drive roll shaft 3a is provided with two sets of bevel gears 4a1, 4a2. The remaining two hole-type rolls (hereinafter also referred to as “driven hole-type rolls”) 2b and 2c as the driven hole-type rolls are respectively connected to the respective roll axes (hereinafter also referred to as “driven-roll axis”) 3b and 3c. The bevel gears 4b and 4c are provided to mesh with the bevel gears 4a1 and 4a2 of the drive roll shaft 3a, respectively.

  In the stand 1 shown in FIG. 3, the input shaft 6 is connected to the horizontal power shaft 11 of the drawing mill through the coupling 5 in a state where the stand 1 is mounted on the drawing mill. At the time of drawing rolling, with the rotation of the power shaft 11 (see the white arrow in FIG. 3), the power of the rotation is transmitted to the input shaft 6 and the drive roll shaft 3a through the coupling 5, thereby The drive hole type roll 2a is rotated (refer to the thick arrow in FIG. 3). Along with the rotation of the drive hole type roll 2a, the power of the rotation is via the bevel gears 4a1 and 4a2 of the drive roll shaft 3a and the bevel gears 4b and 4c of the driven roll shafts 3b and 3c. As a result, the driven hole type rolls 2b and 2c are rotated (see broken line arrows in FIG. 3).

  On the other hand, the even-numbered stand 1 shown in FIG. 4 has a configuration in which the phase angle of the roll arrangement is shifted by 60 ° with respect to the odd-numbered stand 1 shown in FIG. That is, the stand 1 shown in FIG. 4 has a configuration in which the configuration of the stand 1 of FIG. 3 described above is inverted up and down. For this reason, in the even-numbered stand 1 shown in FIG. 4, the drive hole type roll 2a is arranged on the pass line L. With this roll arrangement as a reference, the odd-numbered stand shown in FIG. In the roll arrangement No. 1, the phase angle is shifted by 60 °.

  In the odd-numbered stand 1 shown in FIG. 3, the drive hole type roll 2a is arranged below the pass line L, whereas in the even-numbered stand 1 shown in FIG. 2a is arranged on the pass line L. For this reason, although the position of the power shaft 11 is alternately switched up and down at each stage along the pass line L, the power shaft 11 is still horizontally extended from the same direction. However, the stand 1 shown in FIG. 3 may be used as an even-numbered stage stand, and the stand 1 shown in FIG. 4 may be used as an odd-numbered stage stand.

  By the way, the drawing by the three-roll type drawing mill equipped with the normal stand shown in FIGS. 3 and 4 described above, the inner surface of the metal base tube is not restrained by a mandrel bar or the like, and the groove of the perforated roll This is done while the position of the bottom and flange ends alternate by 60 ° around the pass line. For this reason, a difference in contact pressure occurs between the position of the groove bottom and the flange end of the perforated roll and an intermediate position between them, resulting in a difference in thickness of the metal base tube. As a result, the obtained metal tube is uneven in thickness, and a phenomenon in which the cross-sectional shape of the inner surface thereof is squared, so-called hexagonal, occurs.

  Conventional techniques for preventing the occurrence of uneven thickness such as hexagonal tension include the following.

  In Patent Document 1, an external gear triaxial drive type roll stand is adopted, and the phase angle of the roll arrangement is set to the fourth stand (a hole type roll having a roll axis extending horizontally below the pass line is arranged. 3 roll squeezing mills, which are changed to 15 ° for the fifth and sixth stands, 30 ° for the seventh and eighth stands, and 45 ° for the ninth and tenth stands, respectively. ing. In the drawing mill disclosed in the same document, the metal tube obtained by drawing rolling has a 24-sided shape with a cross-section of the inner surface having more angles than a hexagonal shape, so that the wall thickness is uniformed as a whole. As a result, the occurrence of uneven thickness can be prevented.

JP 2005-169466 A

  As described above, since the drawing mill disclosed in Patent Document 1 is obtained by changing the phase angle of the roll arrangement to an angle different from 60 ° which is normally used, the cross section of the inner surface of the metal tube obtained by drawing rolling. It can be said that the shape becomes a polygon having more corners than the hexagon, and the occurrence of uneven thickness of the metal tube can be prevented.

  However, since the drawing mill disclosed in Patent Document 1 adopts an external gear type stand, the structure around the stand is complicated in the first place. In addition, if the phase angle of the roll arrangement is changed to other than 60 °, it is necessary to significantly modify the structure around the stand such as a stand installation stand, a stand carry-in / out mechanism, and a power mechanism. Therefore, in the drawing mill disclosed in Patent Document 1, a huge facility remodeling cost is generated, and it is impossible to appropriately select and use a stand having a phase angle of 60 ° that is normally used.

  Further, in a drawing mill employing an internal gear type stand, if the phase angle of the roll arrangement is simply changed to other than 60 °, the input shaft and the coupling connected to the drive roll shaft are followed. Tilts and deviates from the position of the power shaft. Therefore, also in this case, it is necessary to remodel the power mechanism around the stand, resulting in equipment remodeling costs, and it is impossible to appropriately select and use a stand having a phase angle of 60 ° that is normally used.

An object of the present invention is to provide an internal gear single-axis drive type roll stand having the following characteristics, and a three-roll drawing mill equipped with this roll stand:
・ It is possible to prevent the occurrence of uneven thickness in the metal tube obtained by drawing rolling.
・ No alterations around the stand are required, and a stand with a phase angle of 60 ° that is normally used can be selected and used as appropriate.

  The gist of the present invention is as follows.

(I) An internal gear single-axis drive type roll stand mounted on a three-roll drawing mill,
The roll stand is
It has an input shaft connected to the power shaft of the drawing mill, and the roll shafts of the three perforated rolls are all inclined with respect to the input shaft, and the power input from the power shaft to the input shaft is 3 A power transmission mechanism composed of a bevel gear that transmits to one of the roll shafts, or a power transmission mechanism composed of an external gear group and a bevel gear, and the power transmitted to the one roll shaft remains A bevel gear that transmits to the two roll shafts of
A roll stand characterized by

  In this roll stand, it is preferable that the one roll shaft is disposed at an angle of 90 ° with respect to the input shaft.

(II) A three-roll type reduction rolling mill equipped with a power shaft over a plurality of stages along a pass line,
The drawing mill is
The roll stand of (I) above;
There is an input shaft connected to the power shaft, and one of the three roll-type roll shafts is connected to the input shaft, and the input from the power shaft to the input shaft and the one roll shaft is input. A roll stand provided with a bevel gear that transmits the generated power to the remaining two roll shafts,
A three-roll drawing mill characterized by

The roll stand of the present invention and the 3-roll drawing mill equipped with this roll stand have the following remarkable effects:
・ It is possible to prevent the occurrence of uneven thickness in the metal tube obtained by drawing rolling.
・ No alterations around the stand are required, and a stand with a phase angle of 60 ° that is normally used can be selected and used as appropriate.

It is a figure which shows typically the whole structure of a drawing mill. It is a schematic diagram which shows the normal arrangement structure of the hole-type roll in the roll stand mounted in a drawing mill. It is a schematic diagram which shows the structure of the normal stand of the odd-numbered stage | steps at the time of employ | adopting the internal gear 1 axis | shaft drive type roll stand. It is a schematic diagram which shows the structure of the normal stand of the even-numbered stage in the case of employ | adopting the internal gear 1 axis | shaft drive type roll stand. It is a schematic diagram which shows the structural example of the roll stand of this invention. It is a schematic diagram which shows the other structural example of the roll stand of this invention. It is a schematic diagram which shows the example of arrangement | positioning structure of the hole-type roll in the roll stand mounted in the drawing mill of this invention. It is a schematic diagram which shows the other arrangement configuration example of the hole-type roll in the roll stand mounted in the drawing mill of this invention.

  In order to achieve the above object, the present inventor has made extensive studies on the premise that an internal gear type stand is adopted. As a result, the following knowledge was obtained.

  (A) If the phase angle of the roll arrangement in the stand is changed to an angle different from 60 ° which is normally used, for example, 30 °, and this stand is mounted on a part of the drawing mill, a metal tube obtained by drawing rolling The cross-sectional shape of the inner surface becomes a polygon having more corners than the hexagon, and the occurrence of uneven thickness of the metal tube can be prevented.

  (B) When the phase angle of the roll arrangement is changed to an angle different from 60 °, the roll axes of the three perforated rolls are all arranged to be inclined with respect to the horizontal power axis. In this case, the input shaft (including the coupling) connected to the power shaft is maintained at the same position as the normal stand shown in FIG. 3 or FIG. 4, and the power input from the power shaft to the input shaft is increased. By transmitting to the drive roll shaft of the three roll shafts via the power transmission mechanism mainly composed of gears, both the drive hole type roll and the driven hole type roll can be rotated. Then, since the input shaft connected to the power shaft is maintained at the same position as that of a normal stand having a phase angle of 60 °, there is no need for modification around the stand of the drawing mill, and the normally used phase angle It is also possible to select and use a 60 ° stand as appropriate.

The present invention has been completed based on the findings (A) and (B). That is, the stand of the present invention is an internal gear uniaxial drive type roll stand mounted on a three-roll drawing mill,
It has an input shaft connected to the power shaft of the drawing mill, and the roll shafts of the three perforated rolls are all inclined with respect to the input shaft, and the power input from the power shaft to the input shaft is 3 A power transmission mechanism composed of a bevel gear that transmits to one of the roll shafts, or a power transmission mechanism composed of an external gear group and a bevel gear, and the power transmitted to the one roll shaft remains And a bevel gear that transmits to the two roll shafts.

Further, the drawing mill of the present invention is a three-roll type drawing mill provided with a power shaft over a plurality of stages along a pass line,
The above roll stand,
There is an input shaft connected to the power shaft, and one of the three roll-type roll shafts is connected to the input shaft, and the input from the power shaft to the input shaft and the one roll shaft is input. And a roll stand provided with a bevel gear for transmitting the generated power to the remaining two roll shafts.

  Below, the preferable aspect of the stand of this invention and a drawing mill is demonstrated.

1. Roll Stand FIG. 5 and FIG. 6 are schematic views showing a configuration example of the roll stand of the present invention. The stand shown in these figures is based on the roll arrangement of the stand shown in FIG. 4 (the drive hole type roll 2a is arranged on the pass line L and the drive roll shaft 3a is horizontal). The phase angle is shifted by ± 30 °.

  In the stand 1 shown in FIG. 5, the input shaft 6 is horizontally disposed at the same position as the stand 1 shown in FIG. 3, and the coupling 5 is connected thereto. In the housing 10 of the stand 1, a hole type having a roll shaft 3 a inclined by 90 ° with respect to the input shaft 6 on the opposite side of the input shaft 6 across the pass line L among the three hole rolls 2. A roll 2a is arranged. This hole type roll 2a functions as a drive hole type roll.

  As with the stand 1 shown in FIGS. 3 and 4, two sets of bevel gears 4a1 and 4a2 are provided on the drive roll shaft 3a of the drive hole type roll 2a. The remaining two driven hole-type rolls 2b and 2c are provided with bevel gears 4b and 4c that respectively mesh with the bevel gears 4a1 and 4a2 of the drive roll shaft 3a.

  In the housing 10, an intermediate shaft 7 that is parallel to the input shaft 6 and extends horizontally is disposed above the hole-type roll 2. The input shaft 6 is provided with an external gear 8a, the intermediate shaft 7 is provided with an external gear 8b at an end on the input shaft 6 side, and these external gears 8a and 8b are two external gears. The gears 8c and 8d are meshed with each other sequentially. Further, a bevel gear 9a is provided at the end of the intermediate shaft 7 on the drive hole type roll 2a side, and a bevel gear 9b that meshes with the bevel gear 9a of the intermediate shaft 7 is provided at the upper end of the drive hole type roll 2a. Yes.

  As the external gear 8a of the input shaft 6, the external gear 8b of the intermediate shaft 7, and the two external gears 8c, 8d meshing with these, a spur gear, a helical gear, a helical gear, etc. are applied. The number of stages of the external gears is not limited. Further, as the bevel gear 9a of the intermediate shaft 7 and the bevel gear 9b of the drive hole type roll 2a meshing therewith, a bevel gear, a bevel gear, a spiral bevel gear, or the like can be applied. The same applies to the bevel gears 4a1 and 4a2 of the drive roll shaft 3a and the bevel gears 4b and 4c of the driven roll shafts 3b and 3c.

  The stand 1 shown in FIG. 5 is mounted on the drawing mill, and the input shaft 6 is connected to the horizontal power shaft 11 of the drawing mill via the coupling 5 in the same manner as the stand shown in FIG. . At the time of drawing rolling, along with the rotation of the power shaft 11 (see the white arrow in FIG. 5), the power of the rotation is transmitted to the input shaft 6 through the coupling 5, and the power transmitted to the input shaft 6. Is transmitted to the intermediate shaft 7 via the external gear 8 a of the input shaft 6, the two external gears 8 c and 8 d, and the external gear 8 b of the intermediate shaft 7, and further the power transmitted to the intermediate shaft 7. Is transmitted to the drive roll shaft 3a via the bevel gear 9a of the intermediate shaft 7 and the bevel gear 9b of the drive roll shaft 3a, whereby the drive hole-type roll 2a is rotated (thick arrow in FIG. 5). reference). Along with the rotation of the drive hole type roll 2a, the power of the rotation is via the bevel gears 4a1 and 4a2 of the drive roll shaft 3a and the bevel gears 4b and 4c of the driven roll shafts 3b and 3c. As a result, the driven hole type rolls 2b and 2c are rotated (refer to broken line arrows in FIG. 5).

  On the other hand, in the stand 1 shown in FIG. 6, the input shaft 6 is horizontally disposed at the same position as the stand 1 shown in FIG. 4, and the coupling 5 is connected thereto. In the housing 10 of the stand 1, among the three hole rolls 2, a hole roll 2 a having a roll shaft 3 a inclined by 90 ° with respect to the input shaft 6 is disposed near the input shaft 6 from the pass line L. Yes. This hole type roll 2a functions as a drive hole type roll.

  As with the stand 1 shown in FIG. 5, two sets of bevel gears 4a1, 4a2 are provided on the drive roll shaft 3a of the drive hole type roll 2a. The remaining two driven hole-type rolls 2b and 2c are provided with bevel gears 4b and 4c that respectively mesh with the bevel gears 4a1 and 4a2 of the drive roll shaft 3a.

  Also, the input shaft 6 is provided with a bevel gear 9c at the end on the drive hole type roll 2a side. The bevel gear 9c meshes with the bevel gear 4a2 disposed above the bevel gears 4a1 and 4a2 of the drive roll shaft 3a.

  As the bevel gear 9c of the input shaft 6 and the bevel gear 4a2 of the drive hole type roll 2a meshing therewith, a bevel gear, a bevel gear, a spiral bevel gear, or the like can be applied. The same applies to the bevel gears 4a1 and 4a2 of the drive roll shaft 3a and the bevel gears 4b and 4c of the driven roll shafts 3b and 3c.

  The stand 1 shown in FIG. 6 is mounted on the drawing mill, and the input shaft 6 is connected to the horizontal power shaft 11 of the drawing mill via the coupling 5 in the same manner as the stand shown in FIG. . At the time of drawing rolling, along with the rotation of the power shaft 11 (see the white arrow in FIG. 6), the power of the rotation is transmitted to the input shaft 6 through the coupling 5, and the power transmitted to the input shaft 6. Is transmitted to the drive roll shaft 3a via the bevel gear 9c of the input shaft 6 and the bevel gear 4a2 of the drive roll shaft 3a, whereby the drive hole-type roll 2a is rotated (thick arrow in FIG. 6). reference). Along with the rotation of the drive hole type roll 2a, the power of the rotation is via the bevel gears 4a1 and 4a2 of the drive roll shaft 3a and the bevel gears 4b and 4c of the driven roll shafts 3b and 3c. As a result, the driven hole type rolls 2b and 2c are rotated (refer to broken line arrows in FIG. 6).

  In the stand 1 shown in FIG. 6, the mechanism for transmitting power from the input shaft 6 to the drive roll shaft 3a is changed to a power transmission mechanism comprising an external gear group and a bevel gear, as in the stand 1 shown in FIG. It doesn't matter.

  The above-described stand shown in FIGS. 5 and 6 has a configuration in which the phase angle is shifted by ± 30 ° with respect to the roll arrangement of the stand shown in FIG. 4, but the phase angle is shifted by ± 15 °. It can also be modified to a configuration shifted by 45 ° or a configuration shifted by 45 °. This is because it can be easily handled by adjusting the installation angle of the bevel gear.

2. Drawing Roller FIG. 7 and FIG. 8 are schematic views showing an example of the arrangement configuration of hole rolls in a roll stand mounted on the drawing mill of the present invention. The drawing mill shown in FIG. 7 replaces the normal stand shown in FIG. 3 as the ninth and eleventh stands (indicated as “# 9” and “# 11” in FIG. 7), and the book shown in FIG. While the stand of the invention is mounted, the tenth and twelfth stands (denoted as “# 10” and “# 12” in FIG. 7) are replaced with the ordinary stand shown in FIG. 4 and the present invention shown in FIG. It is equipped with a stand. The drawing mill shown in FIG. 8 replaces the normal stand shown in FIG. 3 as the fifth and seventh stands (indicated as “# 5” and “# 7” in FIG. 8), and the book shown in FIG. The present invention shown in FIG. 6 replaces the ordinary stand shown in FIG. 4 as the sixth and eighth stands (denoted as “# 6” and “# 8” in FIG. 8). It is equipped with a stand.

  In the stand of the present invention, the phase angle of the roll arrangement is different from the normally used 60 °, but the input shaft connected to the power shaft is horizontal, and the same position as a normal stand having a phase angle of 60 °. Since it is maintained, the drawing mill on which this is mounted does not require modification around the stand, and a stand having a phase angle of 60 ° that is normally used can be appropriately selected and used.

  Further, the drawing mill of the present invention is obtained by drawing rolling because the stand of the present invention, that is, the stand having a roll arrangement phase angle different from the usual 60 ° is mounted on some stages. The cross-sectional shape of the inner surface of the metal tube becomes a polygon having more corners than the hexagon, and the occurrence of uneven thickness of the metal tube can be prevented.

  In the drawing mill of the present invention, the stand of the present invention can be mounted on any stage. In the case of drawing rolling, in order to increase the rotational speed of the perforated roll and increase the tensile force in the direction along the pass line to the metal base tube, the formation of the substantial hexagonal tension It is performed at the stand on the front side with a small force. When excessive hexagonal tension is formed on the front stage stand, uneven thickness is difficult to disperse no matter how much tensile force is applied on the rear stage stand. For this reason, it is preferable to mount the stand of this invention in the front | former stage side rather than the back | latter stage side. Specifically, the stand of the present invention may be mounted by the 12th stand, more preferably by the 8th stand.

  In order to confirm the effect of the present invention, a test for manufacturing an ERW steel pipe was conducted. At that time, using the drawing mill (stretch reducer) shown in FIG. 1, the mounting stand is changed as follows, and a metal base tube having an outer diameter of 114.0 mm is drawn and rolled to an outer diameter of 34. A metal pipe (electrically welded steel pipe) having a wall thickness of 2.8 mm was finished at 0 mm.

[Stand mounting conditions]
Inventive Example 1: As shown in FIG. 7, the ninth and eleventh stands are mounted with the stand having the phase angle of −30 ° shown in FIG. 5, and the tenth and twelfth stands are shown in FIG. A stand with a phase angle of 30 ° is mounted, and the remaining stands are mounted with normal stands with a phase angle of 60 ° shown in FIGS.
Inventive Example 2: As shown in FIG. 8, the fifth and seventh stands are mounted with the stand having the phase angle of −30 ° shown in FIG. 5, and the sixth and eighth stands are shown in FIG. A stand with a phase angle of 30 ° is mounted, and the remaining stands are mounted with normal stands with a phase angle of 60 ° shown in FIGS.
Comparative Example: As shown in FIG. 2, only a normal stand having a phase angle of 60 ° shown in FIGS. 3 and 4 is mounted.

[Evaluation method]
After drawing and rolling, the thickness of each metal tube was measured over the entire circumferential direction, and the standard deviation of the thickness was calculated. For the thickness measurement, a non-contact type laser size measuring device was used. In addition, the time required for changing the stand to each of the above stand mounting conditions was measured.

[Evaluation results]
The standard deviation of the wall thickness was 0.075 mm in the comparative example. On the other hand, it was as small as 0.062 mm in Invention Example 1 and 0.054 mm in Invention Example 2, and the occurrence of uneven thickness could be prevented. In addition, the stand recombination time was the same as in Examples 1 and 2 of the present invention and the comparative example with no inferiority.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used for drawing rolling of all metal pipes such as electric resistance welded steel pipes, forged welded steel pipes, and seamless steel pipes.

1: roll stand, 2, 2a, 2b, 2c: perforated roll,
3a, 3b, 3c: roll shaft, 4a1, 4a2, 4b, 4c: bevel gears,
5: Coupling, 6: Input shaft, 7: Intermediate shaft,
8a, 8b, 8c, 8d: external gear, 9a, 9b, 9c: bevel gear,
10: Housing, 11: Power shaft, L: Pass line, W: Metal base tube

Claims (3)

An internal gear uniaxial drive type roll stand mounted on a three-roll drawing mill,
The roll stand is
It has an input shaft connected to the power shaft of the drawing mill, and the roll shafts of the three perforated rolls are all inclined with respect to the input shaft, and the power input from the power shaft to the input shaft is 3 A power transmission mechanism composed of a bevel gear that transmits to one of the roll shafts, or a power transmission mechanism composed of an external gear group and a bevel gear, and the power transmitted to the one roll shaft remains A bevel gear that transmits to the two roll shafts of
A roll stand characterized by The one roll axis is disposed at an angle of 90 ° with respect to the input axis;
The roll stand according to claim 1. A three-roll drawing mill equipped with a power shaft over a plurality of stages along a pass line,
The drawing mill is
The roll stand according to claim 1 or 2,
There is an input shaft connected to the power shaft, and one of the three roll-type roll shafts is connected to the input shaft, and the input from the power shaft to the input shaft and the one roll shaft is input. A roll stand provided with a bevel gear that transmits the generated power to the remaining two roll shafts,
A three-roll drawing mill characterized by

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