JPH05261409A - Method for rolling tube - Google Patents

Abstract

PURPOSE:To enable the realization of the improvement of rolling efficiency and raising the quality of product by preventing the generation of tear in the terminal part of a material to be rolled without deteriorating the sectional shape and thickness deviation in the terminal part of the material to be rolled. CONSTITUTION:The terminal of the material 3 to be rolled which is fed along the pass center X-X and, while restraining outward expansion with disk rolls 6, which is rolled with inclined rolls 1 is detected with a terminal sensor 60 which is arranged on the inlet side of the inclined rolls 1 and data are supplied to an arithmetic device 65. After the lapse of a prescribed time from the time of detecting the terminal, respective reduction ratios that are set with a device 63 for setting the reduction ratio of disk roll and a device 64 for setting the reduction ratio of inclined roll are instructed by the arithmetic device 65 to the motors M1, M1 for the disk rolls and the motors M2, M2 for the inclined rolls and the revolving speed of the disk roll and the inclined roll is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piercing machine (piercer), which is widely adopted in the Mannesmann pipe manufacturing method, which is a typical method for producing seamless metal tubes, or an inclined rolling machine using a rolling machine (elongator). Rolling method.

[0002]

2. Description of the Related Art Generally, in a seamless metal pipe manufactured by the Mannesmann pipe manufacturing method, a round steel piece which is a material to be rolled is first passed through a piercer, and a center shell is pressed with a plug to penetrate the hole to obtain a hollow shell. This is directly or if necessary, passed through a hollow shell through an elongator for diameter expansion and stretch rolling, and then further stretch rolling with, for example, a plug mill, polishing with a reeler and sizer, shape modification, sizing, and Manufactured through a manufacturing process. By the way, in the above-mentioned piercer and elongator, a so-called inclined rolling machine is used which is a combination of, for example, a barrel-shaped rolling roll having a shaft center inclined with respect to the pass center of a hollow shell (hereinafter referred to as an inclined roll) and a plug. Be done.

A piercer and an elongator used for carrying out the Mannesmann pipe manufacturing method as described above are provided with a pair of inclined rolls facing each other across a predetermined path center and a plug which is an inner surface restricting device arranged on the path center. And a disk roll or a guide shoe as the pipe member guide member are generally used.

FIG. 5 is a schematic horizontal sectional view of the piercer, and FIG. 6 is a vertical sectional view taken along line VI-VI of FIG. In the figure, reference numerals 1 and 1 denote inclined rolls, 2 denotes a plug serving as an inner surface restricting tool, and 6 and 6 denote disk rolls serving as tube guide members.

Each of the inclined rolls 1 and 1 is provided with a gorge portion 11 having a maximum diameter in an intermediate portion in the axial direction, and the diameter of the gorge portion 11 is gradually reduced toward the end on both sides of the gorge portion 11 to form a conical inlet surface. 12 and an exit surface 13 are provided on the left, right or above and below the pass center XX of the material 3 to be rolled.

The plug 2 has a warhead shape as a whole, and its base end is supported by the tip of the mandrel bar M. The plug 2 is positioned and held on the path center XX in the middle of the inclined rolls 1 and 1, and is rotatable about the path center XX. The base end portion of the mandrel bar M is connected to a thrust block in a forward / backward movement device (not shown).

In FIG. 6, disc rolls 6 and 6 are discs each having a concave outer peripheral surface facing the plug 2,
There are a pair of top, bottom, left, and right, which are driven by drive motors (not shown), respectively, and alternate with inclined rolls 1, 1 around the pass center XX of the round steel piece 3b and the hollow shell 3h of the material to be rolled 3. It is located in.

In such a piercer, therefore, the round steel piece 3b of the material 3 to be rolled is transported in the axial direction as indicated by the white arrow, and the inlet surfaces 12, of both inclined rolls 1,1 are transferred. The plug 2 which is bitten between 12 and is screwed to the outer periphery of the tilted rolls 1 and 1 in accordance with the rotation of the inclined rolls 1 and 1 and is rotated to penetrate into the axial position thereof. And is rolled between the plug 2 and the inclined rolls 1 and 1, and the disc rolls 6 and 6 are slidably contacted with the outer periphery of the material 3 to be rolled during rolling and are hollow. Piercing and rolling are performed while pulling out the raw pipe 3h and suppressing bulging outward in the radial direction.

FIG. 7 is a schematic cross-sectional view of the elongator, which has the same structure as the piercer. The hollow shell 31b of the material to be rolled is rolled or expanded while being threadedly moved by the inclined rolls 1 and 1 and the plug 2 to become a rolled tube 31h.

[0010]

However, when piercing and rolling are performed by the above-mentioned piercer and elongator, for example, when the end (rear end) portion of the material 3 to be rolled is piercing-rolled by the piercer, the inclined rolls and Since the contact area with the rolled material 3 is reduced, the acting force in the rolling direction of the disk roll applied to the rolled material 3 may be larger than the rotational force due to the inclined roll. At this time, the rolling slip at the terminal end of the material to be rolled 3 becomes large, and the material is rolled in a state of being pushed out in the rolling direction, and the material to be rolled 3 has a distorted elliptical shape instead of a circular shape. The uneven thickness of the terminal end portion of the material 3 to be rolled deteriorates, causing trouble in the next process.

Further, at the terminal end of the material 3 to be rolled, the contact area with the above-mentioned inclined roll is reduced, and the mandrel bar M supporting the plug 2 is swung by the rotation and the whirling of the material 3 to be rolled. Becomes unstable. For this reason, there is a problem that the material to be rolled 3 is not positioned on the pass line, uneven thickness is generated toward one of the disc rolls, and at the same time, tearing occurs at the edge portion of the disc roll on the one side.

In order to solve this, a method has been proposed in which the disc roll is arranged substantially parallel to the projecting side face of the inclined roll (Japanese Patent Laid-Open No. 63-90306). Although tearing is prevented by this method, there is a drawback that equipment for inclining the disc roll is required, the equipment structure is complicated and the equipment cost is high.

In order to prevent uneven thickness, there has been proposed a method of suppressing uneven thickness generation by giving a rotational speed difference to a pair of inclined rolls. This is a method of detecting the amount of displacement between the axis of the mandrel bar M and the path center during rolling, and applying a rotational speed difference to the pair of inclined rolls so that the amount of displacement becomes zero. It is difficult to actually measure the amount of displacement at the end portion of No. 3, and there is no choice but to make a prediction. In addition, there is a drawback that the amount of displacement changes with temperature, and if the amount of displacement is erroneously predicted, the uneven thickness is deteriorated.

The present invention has been made in view of such circumstances, and does not deteriorate the cross-sectional shape and uneven thickness of the end portion of the material to be rolled and does not cause tearing at the end portion of the material to be rolled. It is an object of the present invention to provide a method for rolling a pipe that can be rolled and that can improve rolling efficiency and improve product quality.

[0015]

According to the present invention, there is provided a method for rolling a pipe according to the present invention, wherein a pair of inclined rolls facing each other with a path center interposed therebetween is rotated to rotate a material to be rolled along the path center. In the rolling method of the pipe for piercing-rolling or stretching-rolling, the bulging of the material to be rolled accompanying this is suppressed by the rotation of a pair of disc rolls facing each other between both inclined rolls, When rolling a predetermined length range from the end of the material to be rolled, the rotation of the inclined roll and the rotation of the disc roll, the speed reduction rate of the rotation speed of the disk roll is made smaller than the speed reduction rate of the rotation speed of the inclined roll. It is characterized by slowing down.

[0016]

In the method of rolling a pipe of the present invention, the end of the material to be rolled during rolling is detected in front of the installation position of the inclined roll by using an appropriate detecting means, and the time point at which this detection is made is used as a reference. As the rotation speed of the disk roll and the inclined roll is reduced, and the rotational speed of the disk roll is made smaller than the rotational speed of the inclined roll, the acting force in the rolling direction of the disk roll can be suppressed, and the elliptical cross-sectional shape is distorted. It is possible to prevent the shape and the uneven thickness ratio from being deteriorated. In addition, since the rotation of the disc roll and the inclined roll is slower than that during the rolling of the rolled material middle part, the rotation speed of the rolled material is reduced and the whirling of the rolled material end part is suppressed to prevent tearing. You can

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing a first embodiment thereof. FIG. 1 is a schematic block diagram showing the structure of a piercer equipped with a cone-type roll used for carrying out the method of the present invention, and FIG. 2 is a schematic plan view showing the positional relationship between each roll and the material to be rolled in this piercer. 3 is a vertical sectional view taken along the line III-III in FIG.

In the figure, reference numerals 1 and 1 indicate the axis of the path center X-
X is a tilting roll that is tilted in different directions with respect to X at a crossing angle γ and at the same time is tilted at a tilt angle β required to move the material 3 to be screwed, and a drive motor M connected to the shaft. _It can be rotated by ₂ and M ₂ . The inclined rolls 1, 1 have a gorge portion 11 at the central portion in the axial direction, and round steel piece portions 3 of the rolled material 3 on both sides of the gorge portion 11.
It has an entrance surface 12 forming an angle θ ₁ with the path center XX of b and an exit surface 13 forming an angle θ ₂ with the path center XX, and the diameter gradually decreases from the gorge portion 11 toward the entrance side and exits from the gorge portion. It is an overall cone-shaped roll with a gradually increasing diameter toward the sides. Further, a mandrel bar M having a warhead-shaped plug 2 is disposed along the path center XX between the inclined rolls 1 and 1. Further, the disk rolls 6 and 6 are discs each having a concave outer peripheral surface facing the plug 2, and have a pair of upper, lower or left and right, and are driven by drive motors M ₁ and M ₁ , respectively, to be rolled. The round steel piece portion 3b and the hollow shell portion 3h of the material 3 are alternately arranged with the inclined rolls 1 and 1 around the path centers XX.

An end sensor 60 for detecting the end (rear end) of the round steel piece 3b is disposed on the entrance side of the inclined rolls 1, 1, and the output of the end sensor 60 is given to the arithmetic unit 65. Be done. In addition to the output of the end sensor 60, the arithmetic unit 65 also has a timer setter that sets the waiting time from the detection of the end of the round steel piece 3b to the deceleration of the disk rolls 6 and 6 and the inclined rolls 1 and 1. Outputs of 61 and 62 and outputs of deceleration ratio setting devices 63 and 64 for setting deceleration ratios of the tilt rolls 1 and 1 and the disc rolls 6 and 6 are given. And the arithmetic unit 65
Is supplied to a disc roll speed controller 66 and a tilt roll speed controller 67 ,. The disc roll speed controller 66 controls the disc roll motors M ₁ and M ₁ to
The tilt roll speed controller 67 is provided to the tilt roll motors M ₂ , M ₂ .

Next, a method of performing piercing and rolling with the apparatus configured as described above will be described. The material 3 to be rolled, which has been heated to a predetermined temperature in the heating furnace, is transferred from the inlet face 12 side of the inclined rolls 1, 1 to the path center XX as shown by the outline arrows in FIG. It is transferred with the axes aligned, and first, the round rope piece 3b at the tip thereof is caught in the inclined rolls 1, 1. After that, the round rope piece 3b is a disc roll 6,6.
Are aligned with the pass center XX, and both inclined rolls 1,
Between the plug 2 and the inclined rolls 1 and 1 which are screwed by the rotation of 1 and penetrate into the axial center position thereof, they are subjected to intermittent reduction once per half rotation to be piercing-rolled. When this rolling is not applied, the rolled material 3 swells in the radial direction due to its rotation as shown in FIG. 3, but the disk rolls 6 and 6 are in sliding contact with the outer periphery of the swollen portion, and As a result of suppressing the outward bulge,
The hollow shell 3h is rolled while having an elliptical shape, and is gradually formed into a circular shape in the moving direction to form a hollow shell 3h.

As shown in FIG. 1, the end position of the material to be rolled 3 is detected by the end sensor 60 arranged on the entrance side of the piercer, and from that time, the disc roll timer setter 61 and the inclined roll timer are set. After waiting for the set value of the device 62, the respective deceleration ratios set by the disc roll deceleration ratio setter 63 and the inclined roll deceleration ratio setter 64 are input to the arithmetic unit 65. Here, the deceleration rate is defined by (rotational speed of roll in intermediate part of rolled material-rotational speed of roll after deceleration) / rotational speed of roll in intermediate part of rolled material. In this arithmetic unit 65, the amount of signal to be actually controlled is calculated based on the value of the deceleration rate set by the deceleration ratio setters 63 and 64, and the end position of the material 3 to be rolled is detected by the end sensor 60. After that, the time is integrated, and when the timer value set by the timer setters 61 and 62 has passed, the signal amounts to be decelerated by the tilt rolls 1 and 1 and the disc rolls 6 and 6 are output.
This calculation output is input to the speed controller 66 for the disc roll and the speed controller 67 for the tilt roll, and these speed controllers 66, 67 respectively drive the motors M ₁ , M ₁ , M ₂ , M ₂ .
Change the speed of ₂ . In this way, the rotation speeds of the disc roll and the tilt roll are reduced.

Further, since the length of the rolled material end portion to be controlled changes depending on the rolling speed of the rolled material 3, the arithmetic unit 65 changes the timer set value according to the rolling speed of the rolled material 3. This makes it possible to arbitrarily change the shape control start position of the end portion of the material to be rolled 3.

Next, the present invention will be described in detail with reference to the drawings showing its second embodiment. FIG. 4 is a schematic plan view showing the positional relationship between the inclined roll and the material to be rolled in the elongator. The same parts as those of the piercer in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The hollow shell 31 is rolled or expanded while being threadedly moved by the inclined rolls 1 and 1 and the plug 2 to form a rolled pipe portion 31h. The method of controlling the shape of the end portion of the hollow shell 31 is the same as that of the first embodiment shown in FIG.
And the speed control device 67 for the tilt rolls changes the speeds of the disc roll motors M ₁ and M ₁ and the tilt roll motors M ₂ and M ₂ , respectively. In this way, the rotational speeds of the disc roll and the inclined roll are decelerated, and the shape of the terminal end of the hollow shell 31 is controlled.

Next, concrete results of the actual piercing and rolling using the method of the present invention will be described. Table 1,
Table 2 shows the implementation conditions and results of the first embodiment in Table 3,
Table 4 is a table showing the implementation conditions and results of the second embodiment.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

Using the piercer having the above-described structure, the control according to the present invention was carried out under the conditions shown in Table 1. Further, as a conventional example in which the rotation speed of the disk roll and the rotation speed of the inclined roll at the terminal end of the material to be rolled is not changed at all, the deceleration rate of the disk roll rotational speed is smaller than that of the inclined roll rotational speed or As a comparative example, the case where the rotational speeds of the disk rolls were made equal to each other, that is, the rotational speeds of the disk rolls were made greater than or equal to the rotational speeds of the inclined rolls, were performed. Similarly, the control according to the present invention was performed under the conditions shown in Table 3 using the elongator having the above-described configuration. Both the conventional example and the comparative example were carried out.

When piercing-rolling was carried out under the above-mentioned conditions, the roundness in the method of the present invention, the conventional example and the comparative example,
Table 2 shows the results of the thickness deviation and the presence or absence of tearing. However, in Table 2, the "x" mark indicating the presence or absence of tearing indicates the state of tearing, and the "O" mark indicates the state of no tearing. To determine the cross-sectional shape at the end of the hollow shell 3h, roundness (maximum outer diameter / minimum outer diameter) ≤1.05 is set as "○", and circularity> 1.05 is set as "x", and the uneven thickness ratio ( (Maximum wall thickness-minimum wall thickness) / average wall thickness) is the average value P of the uneven wall thickness ratio in the circumferential direction at the length of the end portion 300 mm of the hollow shell 3h of less than 6%, "○", and 6% or more. It was set as "x". The average value P of uneven thickness ratio is obtained by the equation 1.

[0031]

[Equation 1] x _i is the wall thickness deviation in the circumferential direction at an arbitrary point, and N is the number of measurement points at which x _i is measured in the longitudinal direction of the hollow shell.

As is clear from Tables 2 and 4, in the case of the conventional example, the cross-sectional shape of the end portion of the hollow shell has an elliptical shape, and the uneven thickness ratio is deteriorated. Also, tearing occurred at the terminal end. Further, in the comparative example, when the deceleration rate of the disk roll and the inclined roll is increased, the splitting is less likely to occur than when the deceleration rate is decreased, but in any case, the cross-sectional shape is elliptical and the uneven thickness ratio is deteriorated. According to the method of the present invention, in the piercer and the elongator, the sectional shape of the end portion of the rolled portion was circular, the uneven thickness ratio was less than 6%, and the end portion was not torn.

Although a cone-shaped roll is used in this embodiment, a barrel-shaped roll may be used.

[0034]

As described in detail above, in the method of the present invention, the rotation of the disk roll and the inclined roll is decelerated within a predetermined length range from the end of the material being rolled.
Furthermore, since the deceleration rate of the disc roll rotation speed is made larger than the deceleration rate of the inclined roll rotation number, it is possible to suppress the acting force in the rolling direction of the disc roll, so that the cross-sectional shape exhibits a circular shape and the uneven thickness rate. Can be prevented from worsening.
Further, since the rotations of the disk roll and the inclined roll are slowed down compared with the time of rolling the intermediate portion of the material to be rolled, whirling of the terminal end portion of the material to be rolled can be suppressed and tearing can be prevented.
As a result, the rolling efficiency is improved and the quality of the product can be improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a configuration of a piercer or an elongator used for implementing the present invention.

FIG. 2 is a schematic plan view showing the positional relationship between each roll and the material to be rolled in the piercer for explaining the present invention.

FIG. 3 is a vertical sectional view taken along the line III-III in FIG.

FIG. 4 is a schematic plan view showing a positional relationship between an inclined roll and a material to be rolled in an elongator for explaining the present invention.

FIG. 5 is a schematic cross-sectional view of a piercer for explaining a conventional technique.

6 is a vertical sectional view taken along line VI-VI of FIG.

FIG. 7 is a schematic cross-sectional view of an elongator for explaining a conventional technique.

[Explanation of symbols]

1 Tilt roll 2 Plug 3,31 Rolled material 3b Round steel piece 3h Hollow tube 6 Disc roll 60 End sensor 63 Disc roll deceleration ratio setter 64 Tilt roll deceleration ratio setter 65 Computing device 66 Disc roll Speed controller 67 Speed controller for tilt rolls M ₁ Disk roll motor M ₂ tilt roll motor

Claims (1)

[Claims] 1. A rolled material rolled by a pair of inclined rolls facing each other with a path center interposed therebetween is rolled by the inclined rolls, and the rolled material is rolled by the inclined rolls. Bulging, in the rolling method of the pipe to be piercing-rolled or stretch-rolled by suppressing the rotation of a pair of disc rolls facing each other between both inclined rolls, in rolling in a predetermined length range from the end of the material to be rolled, The rotation of the inclined roll and the rotation of the disc roll,
A method for rolling a pipe, characterized in that the speed of deceleration of the rotational speed of the disk roll is made larger than the speed of deceleration of the rotational speed of the inclined roll to decelerate.