JPS5994515A - Method for controlling outer diameter in seizer - Google Patents

Abstract

PURPOSE:To improve the outer diam. controlling accuracy of a product steel pipe, by setting respectively the extents of control with respect to the reference set values of respective distances between the bottoms of roll grooves of at least the final stands of respective stands in odd and even numbers to the specified values, in a final seizing stage for manufacturing a seamless steel pipe from a cylindrical billet. CONSTITUTION:After heating a cylindrical billet 1 by a heating furnace 2, the billet 1 is formed into a sizer blank pipe 10 by a piercer 3, an elongator 5, a plug mill 7 and a reeler 9, and a finished pipe 13 is manufactured by finishing the pipe 10 by means of a sizer 12 after heating the pipe 10 by a reheating furnace 11. In this case; the sizer 12 is formed by arranging continuously plural roll stands consisting respectively of a pair of groove rolls of which arrangement is mutually changed by 90 deg., and the extents of control with respect to the reference set values of respective distances between the bottoms of roll grooves of at least the final stands of respective stands in odd and even numbers are respectively set to the specified values; then the outer diam. controlling accuracy of a finished pipe 13 at the normal temperature is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the outer diameter of a sizer in which a plurality of roll stands, each consisting of a pair of grooved rolls, are successively arranged with their arrangement changed by 90 degrees from each other.

FIG. 1 is a process diagram showing the manufacturing process of a general seamless steel pipe, in which a round billet 1 is heated to a predetermined temperature in a rotary hearth type heating furnace 2, and then a piercer 3 as a first piercing rolling mill A short hollow piece with a hollow hole 4
becomes. The thick-walled hollow piece 4 is reduced in wall thickness and lengthened by an elongator 5 serving as a second piercing rolling mill, and becomes a plug mill blank tube 6. The plug mill raw tube 6 is further stretched to reduce its thickness by a plug mill T serving as an elongation rolling mill, and becomes a reeler tube 8. The inner and outer surfaces of the reeler tube 8 are smoothed by a reeler 9, which is a polishing machine, and the sizer tube 10 is reheated in a walking beam reheating furnace 11. The finished tube 13 is formed into an external shape with high accuracy.

Here, the sizer 12 is a multi-stage rolling mill in which 5 to 8 roll stands each consisting of a pair of slotted rolls are successively arranged at 90 degrees with each other. The outer diameter of the sizer tube 10 is B
It is said to be more than 0chi.

In this type of 20-hole sizer 12, for example, the outer diameter of the finished tube 13 in the direction of the roll groove bottom spacing of the odd-numbered final stand generally does not match, and the roll groove bottom spacing of the even-numbered final stand does not match. The outer diameters of the finished tubes 13 in this direction also do not match. This is based on the fact that during the deformation process of the tube material, when one outer diameter is reduced, a flattening phenomenon occurs in which the outer diameter in the 90 degree direction expands. Therefore, even if the groove bottom spacing in the final stands of odd and even numbers is set equal to the target finished tube outer diameter, it is not possible to obtain a product having the desired finished tube outer diameter and roundness.

Therefore, various methods of controlling the outer diameter have been proposed in which the outer diameter of the finished tube rolled by the 20-inch sizer is set as a target value. As a side note, in the "Outer diameter control method in a pipe forming machine" according to Japanese Patent Application Laid-Open No. 57-44411, the distance between the roll groove bottoms of the final two stands and the corresponding outer diameters of the exit side pipe material in two directions are determined by rolling. The influence coefficient of the roll groove bottom spacing in the two directions on the outlet tube material outer diameter is determined, and this influence coefficient is used to control the roll groove bottom spacing of the final two stands.

However, in the conventional outside diameter control method described above, only the influence of the flattening phenomenon that occurs during the deformation process of the tube material is taken into account, and the influence of fluctuations in the outside diameter of the entry side tube material on the outside diameter of the exit side tube material is not considered at all. Therefore, it is not possible to stabilize the accuracy of controlling the outer diameter of the finished pipe.

An object of the present invention is to provide an outer diameter control method in a sizer that can stabilize the outer diameter control accuracy of a finished pipe.

In order to achieve the above object, the outer diameter control method for the sizer according to the present invention provides an influence coefficient ( C1) and the influence coefficient (C2) on the outer diameter (C2) in the direction perpendicular to the core direction of the exit pipe material, and the roll groove bottom interval (B2) of at least the final stand of even numbers.
) on the outer diameter (C1) of the outlet pipe material in the direction orthogonal to the direction (β1) and the influence coefficient (A2) on the outer diameter (C2) of the outlet pipe material in the direction (C2) #ζ and +Z, odd numbers The influence coefficient (γ
1) The influence coefficient (r2) of the outer diameter (A2) of the inlet pipe material in the direction of the bottom of the roll groove of the even-numbered stands on the outer diameter (C2) of the exit pipe material in that direction is determined in advance, and each of the above-mentioned shadows 4 Coefficient (al 1 C2?β1tβz t rx +
rz ), the deviation value (ΔA1
．． ΔA2), the deviation value (ΔC8, ΔCz) of the exit side outer diameter (Cyu, C2) in the above two directions of the preceding material that is the same lot as the material to be controlled (ΔC8, ΔCz), The reference set value of the roll groove bottom spacing (Bs, Bz) of at least the last stand of odd and even numbers, with the exit outside diameter (C1, C7) as the target value - the corresponding control amount (ΔB, ΔB, ) is defined by .

The principle of the present invention will be explained below.

Bl is the roll groove bottom interval in at least the last stand of the odd number in the sizer, ΔBIs is the control amount for the reference setting value B1o of the roll groove bottom interval B1, B2 is the roll groove bottom interval in at least the last stand of the even number,
The control amount for the reference setting value B20 of the roll groove bottom distance 114B2 is set to ΔB2, and the roll groove bottom direction of the odd numbered stands (
The outer diameter of the outlet tube material in the direction perpendicular to the roll groove bottom direction of the even numbered stands is 1s.The outer diameter C1 of the outlet tube material is 1s.
ΔC1 is the deviation value from the target value C The deviation value of the diameter C2 from the target value C2o is Δ
C2, the outer diameter of the entry side tube material in the bottom direction of the roll groove of the odd numbered stand is A□, the reference value AI of the outer diameter A1 of the above entry side tube material
(If the deviation value from 1 is ΔA1, the outer diameter of the entry side tube material in the direction of the bottom of the roll groove of the even-numbered stand is A2, and the deviation value of the outer diameter A2 of the entry side pipe material from the reference value A20 is ΔA2, the above roll The influence coefficient of the groove bottom interval B1 on the outer diameter C1 of the outlet pipe material is C1, and the roll groove bottom interval B is
□The influence coefficient on the outer diameter C2 of the above outlet pipe material is C2,
βl is the influence coefficient of the roll groove bottom interval B2 on the outer diameter C1 of the outlet pipe material, A2 is the influence coefficient of the roll groove bottom interval B2 on the outer diameter C2 of the outlet pipe material, If the influence coefficient of 〇 to the diameter on the outer diameter C1 of the outlet pipe material is r8, and the influence coefficient of the outer diameter A2 of the inlet pipe material on the outer diameter C2 of the outlet pipe material is r2, then the following (1) is obtained. Equation and Equation (2) hold true.

ΔC1=α1ΔB, +β1ΔB2+ r1ΔA1−
(1) ΔC2=α2ΔB8+β2ΔB2+r2ΔA2・
・+21, and ΔA1 for each of the three sets obtained from the rolling results of the same lot. ΔA2. ΔB1. ΔB2. ΔC1t
Create three equations (1) and (2) based on ΔC2, and solve all six equations as simultaneous equations using the above-mentioned influence coefficients α1. C2, β1. A2 + '11γ2
can be determined in advance.

Therefore, each of the above influence coefficients α1. C2, β1. β2゛.

'1+r2, the above deviation value ΔA3 of the entry side outer diameter A of the material to be controlled in the above two directions, , A2. By using ΔA2 and the deviation values ΔC1 and ΔC2 of the exit outside diameter CI + 02 in the two directions of the preceding material that is the same lot as the material to be controlled, the above equations (1) and (2) can be transformed. According to the following equations (3) and (4), the roll groove bottom interval B1. The above control amount ΔB1 with respect to the reference setting value of B2
．． It becomes possible to obtain ΔB2.

(Figure 2 is a control system diagram showing a sizer used in the implementation of the present invention. This sizer 12 consists of five roll stands, and adjacent roll stands are 90 degrees apart from each other.
They are arranged consecutively, changing the arrangement every time.

On the outlet side of the sizer 12, there are a first outlet outer diameter measuring device 21A and a second outlet outer diameter measuring device 21B as shown in FIG.
An outlet outer diameter measuring device 21 consisting of the following is provided. 1st
The exit outer diameter measuring device 21A is capable of measuring the outer diameter C1 of the exit pipe material in the roll groove bottom direction of the odd numbered stands (direction perpendicular to the roll groove bottom force direction of the even numbered stands).

Further, the second outlet outer diameter measuring device 21B is capable of measuring the outer diameter C2 of the outlet tube material in the roll groove bottom force direction of the even numbered stands (direction perpendicular to the roll groove bottom direction of the odd numbered stands).

Also, on the entry side of the sizer 12, there is an entry side outer diameter measuring device 3) device 2.
2 are arranged. The entry side outer diameter measuring device 22 can measure the outer diameter A8 of the entry side tube material in the direction of the roll groove bottom of odd numbered stands, the low/L of even numbered stands, and the outer diameter A2 of the entry side tube material in the direction of the groove bottom. It is said that

The above-mentioned outlet outer diameter measuring device 21 and inlet outer diameter measuring device 22
Each measurement result can be transmitted to the arithmetic unit 23.

The arithmetic unit 23 calculates each of the influence coefficients α1. C2, β1°A2 + r, l r2 is calculated based on the above equations (1) and (2). Therefore, the calculation device 23 calculates the deviation values ΔC1+ΔC2 of the respective outer diameters C1 and C2 of the outlet pipe material from the target values C1o and C2o based on the measurement results of the respective outer diameter measuring devices 21 and 22. Rule 1 Each outer diameter of the pipe material A1. Reference value AIo of A2, deviation value ΔA1 from A2o. Calculate ΔA2. Furthermore, the arithmetic unit 23 calculates each of the above influence coefficients α1
．． C2, β1. A2゜rl T 12, each deviation value ΔA1
．． ΔA2. Based on ΔC3 and ΔC2, the roll groove bottom interval B1. The control amount ΔB1+ΔB2 for the reference setting values B101 to B20 of B2 is calculated, and the calculation result is transmitted to the control device 24.

The control device 24 sets the lowering position of the odd-numbered last stand, that is, the fifth stand 12 (5) to its reference setting value nso.
At the same time, the lowering position of the even-numbered final stand, that is, the fourth stand 12 (4) is changed by the above-mentioned ΔB2 from the reference set value B20. Note that the control device 24 controls at least the fifth stand 12 (5).
If the rolling position is changed by the above ΔB8,
The other odd-numbered stands 12(1), 12(3) may also have their lowered positions changed by the above ΔB1, and at least the lowered position of the fourth stand 12(4) may be changed by -F notation ΔB2. Anything that changes only
The lowered position of the other even-numbered stands 12(2) may also be changed by the above-mentioned ΔB2.

According to the above embodiment, it is possible to simultaneously consider both the influence of the roll interval on the outer diameter variation of the outlet pipe material and the influence of the outer diameter of the inlet pipe material, and compared to the conventional example, it is possible to It becomes possible to greatly reduce the amount of variation in the outer diameter of the outlet tube material.

Next, the specific effects obtained when the present invention is applied are shown in FIG. 4 in comparison with the conventional method.

That is, in FIG. 4, the vertical axis shows the deviation value ΔC from the target value of the exit side control, the horizontal axis shows the rolling number n from the start of the control, and the cold target outer diameter is 244.5 m, the wall thickness is 11. 99
This is a diagram showing a comparison of the variation in the outer diameter of the outlet tube material based on the conventional control method and the variation in the outer diameter of the outlet tube material based on the control method of the present invention when rolling the Wm tube material with a 7-stand finish. be. Here, the rolling reduction set value was manually set in advance to deviate from the standard setting state, and after switching to automatic control, a fourth pipe material whose outside diameter was larger than the standard value was intentionally rolled. According to Fig. 4, the conventional method does not take into account the influence of the outer diameter of the inlet pipe, so it is recognized that changes in the outer diameter of the inlet pipe are directly reflected in the outer diameter of the outlet pipe. However, in the case of the control method according to the present invention, it is recognized that it is possible to control the outer diameter of the outlet pipe material to a target state by taking into account the change in the outer diameter of the inlet pipe material.

As described above, according to the method for controlling the outer diameter of a sizer according to the present invention, it is possible to stabilize the accuracy of controlling the outer diameter of a finished pipe.

[Brief explanation of drawings]

Figure 1 is a process diagram showing the manufacturing process of general seamless steel pipes.
Fig. 2 is a control system diagram showing the sizer used to carry out the present invention, Fig. 3 is a front view showing the outside diameter measurement state of the pipe material on the exit side of the sizer, and Fig. 4 shows the control results according to the present invention and the conventional method. FIG. 3 is a diagram comparing and illustrating control results according to examples. 12... Sizer, 13... Finished tube, 21.
...Outside outer diameter measuring device, 22...Inlet outer diameter measuring device, 23...Arithmetic device,
24...Control device, 25...Downward motor O agent Patent attorney Osamu Shiokawa

Claims (1)

[Claims] (1) In a method for controlling the outer diameter of a sizer in which a plurality of roll stands each consisting of a pair of hole-shaped rolls are successively arranged at 90 degrees from each other, the groove bottom spacing (B1) of at least the last stand of an odd number The influence coefficient (α, ) exerted on the outer diameter (C1) of the outlet pipe material in the direction, and the influence coefficient (C2) exerted on the outer diameter (C2) of the outlet pipe material in the direction orthogonal to the direction, the even-numbered at least The influence coefficient (β□) of the roll groove bottom spacing (B2) of the final stand on the outer diameter (C8) of the outlet tube in the direction perpendicular to the direction, and the influence on the outer diameter (C2) of the outlet tube in the direction Influence coefficient (β2)
, the influence coefficient Cr*] of the outer diameter (Al) of the inlet tube in the direction of the bottom of the roll groove of odd-numbered stands on the outer diameter (C1) of the outlet tube in that direction; The influence coefficient (r2) that the outer diameter (A2) of the side tube material has on the outer diameter (C2) of the outlet tube material in this direction is determined in advance, and each influence coefficient (C1, C2, A0.A2゜γ1) is determined in advance.
1r2)% Entry side outer diameter of the material to be controlled in the above two directions (
The deviation value (ΔA1゜ΔA) from the reference value of A□, A2)
2) Based on the deviation values (ΔC1, ΔC2) from the target values of the outlet outer diameter (C1, C2) in the two directions of the preceding material that is the same lot as the material to be controlled, The control amount (ΔB!+ΔBz) for the standard setting value of the roll groove bottom interval (B□.B2) of at least the final stand of - number and even number, with the exit outside diameter (C□. ”2) as the target value.
) is determined by 41 [Outer diameter control method in sizer.