JPH08197111A - Method for controlling speed of rotation of roll in reducer - Google Patents

Abstract

PURPOSE: To prevent roll slip and to completely eliminate the generation of the collision of a tube between respective stands by executing drooping to the speed of rotation of rolls of a reducer in accordance with the load of an electric welded steel manufacturing line. CONSTITUTION: In the case of an electric resistanse welded tube 4, drooping is executed to the speed of rotation of the rolls 9 of the reducer 3 in accordance with the load. The amount 8 of load to the whole mill is detected and drooping ratio DR is changed based on an equation by the magnitude of the load. Equation: Drooping raio DR = Rated load/Amount of Load × D. Where, D: The amount of the specified drooping corresponding to the rated load. The corrected speed S of the set speed S1 at a 1st stand by the drooping ratio DR determined by the equation is determined by S = S1 × DR About the stands on and after the 2nd stand, the drooping of the set speed is also similarly executed. In this way, roll slip at each stand is dissolved and the generation of collision of the tube between respective stands is completely eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roll speed control method for a reducer, which is a pipe drawing and rolling machine incorporated in an electric resistance welded steel pipe production line.

[0002]

2. Description of the Related Art In an electric resistance welded steel pipe production line, equipment for manufacturing a small diameter precision electric resistance welded steel pipe by incorporating a reducer which is a pipe drawing and rolling machine is adopted. Also, the reducer
Since products of various sizes can be obtained from the same size of the mother pipe, the mother pipe size can be integrated.

Conventionally, in the roll rotation speed control of the reducer in the electric resistance welded steel pipe production line, only the pipe outer diameter and the wall thickness are manufactured within a relatively limited range, and the roll rotation speed is manually set. It was the mainstream. Manual setting of the roll rotation speed of the reducer requires skill and time because the operator senses the torque balance and roll slip of each stand and operates the roll rotation speed set value up and down. Normally, the roll rotation speed of each stand in the reducer is estimated by estimating the pipe elongation amount based on the outer diameter of the pipe and the hole-type roll diameter of each stand, and then determining the pipe speed of each stand based on that to determine the roll rotation speed. I have decided.

As another method, the relationship between the roll rotation speed of each stand and a control amount (hereinafter referred to as a taper amount) that determines the distribution thereof is set in advance, and the relationship between the taper amount and the elongation rate of the pipe is preliminarily tested. That is, the relationship between the elongation rate of the pipe and the taper amount, and the taper amount and the roll of each stand so that the pipe after rolling has a predetermined length according to the measured length before rolling. A method of adjusting the roll rotation speed of each stand according to the relationship with the rotation speed (Japanese Patent Publication No. 51-43483, Japanese Patent Laid-Open No. 60-21114), or
(A) The cross-sectional area of the pipe for each stand, which is determined by the rolling schedule, is set in advance, and (b) the material weight and the mother pipe length before squeeze rolling are measured, and the commanded material weight and the commanded mother pipe length in the same lot and those Based on the actually measured weight and the actually measured length, the ratio of the sectional area of the pipe on the inlet side of the reduction rolling mill is calculated, and (c) the sectional area of the pipe for each stand in (a) above is compared, The cross-sectional area correction ratio for each stand is obtained, and (d) the length of the pipe after the squeeze rolling is measured, and based on the length of the pipe after the squeeze rolling determined from the rolling schedule and the measured length, Find the cross-sectional area ratio of the pipe,
(E) Compared with the cross-sectional area of the pipe for each stand in (a) above, obtain the cross-sectional area correction ratio for each stand from the outlet side,
(F) Obtaining the cross-sectional area correction ratio for each stand from (c) and (e), (g) converting the cross-sectional area correction ratio for each stand in (f) above into a roll rotation correction ratio for each stand,
Calculate the roll rotation speed for each stand, (h) above (g)
A method for controlling the length of the rolled tube to a predetermined value by adjusting the roll rotation speed for each stand (Japanese Patent Laid-Open No. 62-62,091).
No. 248,505) has been proposed.

[0005]

However, the above technique is for controlling hot steel pipes and is difficult to apply to cold-welded steel pipes. In addition, recently, the production range of ERW steel pipes has expanded, which requires various reduction patterns for the reducer, and the number of stands also fluctuates greatly. In addition, the product ERW steel pipe,
With the progress of smaller lots, it has become difficult to manually set the number of rotations of the roll, which requires a long time.

In the method disclosed in Japanese Patent Publication No. 51-43483 and Japanese Patent Laid-Open No. 60-21114, the taper amount, which is an intermediate parameter independent of rolling characteristics, is used when determining the roll rotation speed of each stand. Therefore, there is a drawback that the relationship between the elongation rate of the pipe and the taper amount changes variously and the length of the pipe after rolling changes. Furthermore, JP-A-6
The method disclosed in JP-A-2-248505 obtains the roll rotation speed of each stand on the basis of the cross-sectional area of the tube of each stand, requires complicated calculation, and sets the roll rotation speed in a short time. There is a drawback that you cannot do it.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a roll rotation number control method for a reducer, which can determine the roll rotation number for each stand of the reducer without skill.

[0008]

[Means for Solving the Problems] The inventors of the present invention have made extensive studies to achieve the above object. As a result, the reduction distribution for each stand of the reducer specified by the type and size of the electric resistance welded steel pipe is set, and the roll initial rotation speed for each stand is provisionally set according to the set reduction amount and roll hole die diameter. After starting operation with a number,
The tube speed is detected by the speed detectors installed on the inlet and outlet sides of the reducer to calculate the amount of expansion of the tube, and based on the amount of expansion, the correction amount of the reduction amount for each stand is calculated and the roll initial rotation for each stand is performed. It was found that the object can be achieved by drooping the mill set speed to correct the number and prevent slipping during operation, and arrived at the present invention.

That is, the present invention relates to a roll rotation speed control method for a reducer in an electric resistance welded steel pipe production line,
The reducer outer diameter reduction amount is determined according to the product type and size, and the roll rotation speed of each stand is provisionally set based on the determined outer diameter reduction amount, roll hole die diameter for each stand, and mill speed. The elongation amount is calculated from the pipe speed detected by the speed detectors installed before and after the roll speed setting is corrected by the outer diameter reduction amount of each stand, and the reducer's This is a roll rotation speed control method for a reducer, characterized in that the roll rotation speed is drooped.

[0010]

The outer diameter reduction amount R in the present invention can be obtained by the following equation. R = (a ₀ −a) / a ₀ × 100 (%) where R: outer diameter reduction amount, a ₀ : outer diameter before drawing, a: outer diameter after drawing determined reduction amount R and each stand Based on the roll hole die diameter for each, the roll initial rotation speed for each stand is calculated and set based on the following formula. First stand initial rotational speed setting value _{= [S 1 × (1 +} r 1/2)] / roll caliber diameter, however, Si: mill set speed, r _1: the first stage mill set reduction amount second stand and subsequent initial rotational speed set point = [(Previous stage rotation speed setting value / previous stage roll hole die diameter) x (1 + r _i / 2)] / roll hole die diameter where r _i : reduction amount of i stand (i = 2,
... n)

After the operation is started with the initial rotational speed set value, the elongation amount S (%) is calculated from the pipe speed detected by the speed detectors installed before and after the stand group. Next, the rotation speed correction ratio of each stand is calculated based on the following formula. 1 + S / 100 = [1+ (r ₁ × α) / 100 × 1 /
2] [1+ (r ₂ × α) / 100 × 1/2] ... [1+
(R _n × α) / 100 × 1/2] where r _i : reduction amount of i stand (i = 1,
2 ... n) α: correction amount ratio Based on the correction amount ratio α calculated above, the rotation speed of each stand is reset by the following formula. 1st stand Revised rotation speed setting value = [S ₁ × (1 + r ₁ × α / 2)] /
Roll caliber diameter second stand and subsequent reviewing rotational speed setting value = [(front rotational speed setting value / front roll caliber _{diameter) × (1 + r i ×} α / 2)] / roll grooved diameter

Further, in the present invention, in order to prevent roll slip during operation, drooping control is introduced at the mill set speed. Normally, drooping is set by the ratio of the motor rated speed to the motor rated torque, but in the case of electric resistance welded steel pipe, the size is wide, so the load is also wide, and the entire mill should be prepared to handle these. The load is detected, and the drooping ratio D _R is changed according to the following formula according to the magnitude of the load. Drooping ratio D _R = Rated load / Load amount × D where D: Specified drooping amount corresponding to rated load Drooping at the mill setting speed S ₁ by the drooping ratio D _R obtained by the above formula is S = S _Performed by ₁ × DR.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to FIGS. FIG. 1 is a control system diagram showing a roll rotation speed control method for a reducer according to the present invention, and FIG. 2 is a flowchart of correction of initial rotation speed temporary setting.
In FIG. 1, 1 is a squeeze roll for welding both edges of an open pipe 2 by pressure welding, 3 is a reducer consisting of a large number of stands for drawing and rolling an electric resistance welded steel pipe 4, and 5 is a speed detector provided on the inlet side of the reducer 3. , 6 is a speed detector also provided on the outlet side of the reducer 3, 7 is a roll speed control unit of the reducer 3, and the electric resistance welded steel pipes on the inlet side and the outlet side of the reducer 3 measured by the speed detectors 5 and 6 are provided. A speed of 4 is entered. Further, the roll speed control unit 7 includes a reducer 3
The roll hole die diameter and the outer diameter reduction amount of each stand are input from the entire mill load 8 and a host computer or a console (not shown).

Reference numeral 9 is a hole type roll of each stand, 10 is a drive motor of each stand, and 11 is a drive motor 1 of each stand.
The operation unit of 0 is configured to control the roll rotation number for each stand based on a command from the roll rotation number control unit 7. Further, the roll rotation speed control unit 7 determines the number of stands of the reducer 3 and the outer diameter reduction amount R based on the product type and the pipe size input from the host computer or the console. The outer diameter reduction amount R is determined by R = (a ₀ −a) / a from the outer diameter a ₀ before the drawing and the outer diameter a after the drawing.
_It is calculated by ₀ × 100 (%).

Then, the roll rotation speed control unit 7 calculates the roll initial rotation speed for each stand based on the determined reduction amount R and the roll hole die diameter for each stand based on the following formula, An initial rotation speed for each stand is commanded to each operation unit 11. First stand initial rotational speed setting value _{= [S 1 × (1 +} r 1/2)] / roll caliber diameter, however, S _1: mill set speed, r _1: the initial rotational speed setting stage mill set reduction amount second stand and subsequent Value = [(previous stage rotation speed set value / previous stage roll hole die diameter) × (1 + r _i / 2)] / roll hole die diameter where r _i : reduction amount of i stand (i = 2,
... n)

The operation unit 11 for each stand is based on the command of the initial rotation speed input from the roll rotation speed control unit 7.
The drive motor of each stand is controlled by the initial rotation speed setting of each stand to start the reduction rolling of the electric resistance welded steel pipe 4. When the squeeze rolling of the electric resistance welded steel pipe 4 is started, the roll rotation speed control unit 7 determines, based on the speeds of the electric resistance welded steel pipe 4 on the inlet side and the outlet side of the reducer 3, which are input from the speed detectors 5 and 6. The actual elongation amount S (%) of the electric resistance welded steel pipe 4 is calculated, and the correction amount ratio α of each stand is calculated by the following formula. 1 + S / 100 = [1+ (r ₁ × α) / 100 × 1 /
2] [1+ (r ₂ × α) / 100 × 1/2] ... [1+
(R _n × α) / 100 × 1/2] where r _i : reduction amount of i stand (i = 1,
2 ... n) α: correction amount ratio Based on the correction amount ratio α calculated above, the rotation speed of each stand is reset by the following formula. 1st stand Revised rotation speed setting value = [S ₁ × (1 + r ₁ × α / 2)] /
Roll caliber diameter second stand and subsequent reviewing rotational speed setting value = [(front rotational speed setting value / front roll caliber _{diameter) × (1 + r i ×} α / 2)] / roll grooved diameter

In addition, drooping control is introduced at the mill set speed to prevent roll slip during operation.
Normally, drooping is set by the ratio of the motor rated speed to the motor rated torque, but in the case of electric resistance welded steel pipe, the size is wide, so the load is also wide, and the entire mill should be prepared to handle these. The load amount is detected, and the drooping ratio D _R is changed based on the following formula according to the magnitude of the load. Drooping ratio D _R = Rated load / Load amount × D where D: Specified drooping amount corresponding to rated load The correction speed S of the first stand set speed S ₁ by the drooping ratio D _R obtained by the above equation is carried out by S = S ₁ × D _R. For the second stand and thereafter, drooping at the set speed is performed in the same manner as the set speed.

When the roll rotation speed control method of the reducer is adopted and the roll rotation speed control in the drawing rolling of the electric resistance welded steel pipe production line is performed, there is no roll slip at each stand, and the pipe sticking between each stand is eliminated. It was confirmed that there was no occurrence of any trouble.

[0019]

As described above, according to the roll speed control method of the present invention, it is possible to prevent roll slip in a short time without any skill and to prevent a pipe from being caught between stands. You can

[Brief description of drawings]

FIG. 1 is a control system diagram showing a roll rotation speed control method for a reducer according to the present invention.

FIG. 2 is a flowchart of correction of initial rotation speed setting.

[Explanation of symbols]

 1 Squeeze roll 2 Open pipe 3 Reducer 4 ERW steel pipe 5, 6 Speed detector 7 Roll speed control unit 8 Mill load 9 Hole roll 10 Drive motor 11 Operation unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B21B 37/16 37/78

Claims (1)

[Claims] 1. A method of controlling a roll rotation speed of a reducer in an electric resistance welded steel pipe production line, wherein an outer diameter reduction amount of the reducer is determined according to a product type and a size, and the determined outer diameter reduction amount and a roll hole die diameter of each stand are determined. And the roll speed of each stand based on the mill speed, the extension amount is calculated from the pipe speed detected by the speed detector installed before and after the reducer stand group, and the roll rotation is performed according to the outer diameter reduction amount of each stand. A method for controlling the roll rotation speed of a reducer, which comprises correcting the number of rotations and drooping the roll rotation speed of the reducer according to the load of the electric resistance welded steel pipe production line.