JPH02207921A - Straightening method for tube by rotary straightner - Google Patents

Abstract

PURPOSE:To set an accurate set-up by predicting the wear amount of a roll at the external contact point between the roll and a tube to be straightened and setting a roll position and an oblique angle of the roll based on this predicted value. CONSTITUTION:In a method for straightening the tube by a rotary straightner, a wear amount at the external contact point between the roll 2 and the tube 1 to be straightened is estimated based on the wear amount in the central part of the roll 2. Then, a quantity of offset, a quantity of crush and the oblique angle theta of the roll are preset based on the predicted value. In this way, since the roll position and the oblique angle theta of the roll are adjusted finely after they are preset, the straightening effect to the bend and ellipticity of the tube is excellent and roll mark flaws can be prevented from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for straightening a tube using a rotary straightener.

[Conventional technology]

When straightening a pipe using a rotary straightener, setup settings for the straightener are made. FIG. 5 is an explanatory diagram showing the state of tube straightening using a roll-type straightener. b) In the figure, the center axis of tube movement (
3), the offset amount δo2 is applied to the second roll (2).
．． An offset amount δo4 is set for the fourth roll ■,
In addition, as shown in the figure (b), the amount of crushing δ occurs in the second stage roll (2) with respect to the outer diameter d of the tube (1). is set. The roll inclination angle is θ. In setting the roll position and roll inclination angle of the straightener as described above, conventionally, after presetting, the roll inclination angle was finely adjusted using the front surface of the straightening tube that was fitted over the straightener. At that time, the operator should periodically measure the roll diameter at the center of the roll to correct the amount of roll wear.
A method was adopted in which the amount of roll wear at the center of the roll was determined from this value, and this amount of roll wear was used in setting the roll position and roll inclination angle.

[Problem to be solved by the invention]

However, the conventional tube straightening method described above has the following problems. In other words, (1) the amount of roll wear is extremely large at approximately 10 m x 13 months; on the other hand, considering the effect on the roll inclination angle setting, it is necessary to measure with an accuracy of 0.21 cm, and the measurement pitch must be kept quite short. There must be.

(2) In order to improve the accuracy of setting the roll inclination angle, it is necessary to know the amount of roll wear at the external contact point between the roll and the tube, but it is not easy to measure the amount of wear at this external contact point, and as mentioned above, the roll center The amount of roll wear was determined by measuring the diameter at that part.

As mentioned above, conventionally, the amount of roll wear at the external contact point between the roll and the tube, which is necessary to accurately set the roll inclination angle, has not been measured, so it is necessary to fine-tune the roll inclination angle after presetting as described above. In addition, the effect of straightening tube bends and ellipses was poor, and roll mark defects were also a factor.

The present invention solves the above problems and achieves accurate roll position Rfa in straightening pipes using a rotary straightener.
The purpose of the present invention is to provide a method for setting roll angle and roll inclination angle.

[Means to solve the problem]

The present invention provides a method for straightening a tube using a rotary straightener, which is performed by setting appropriate off-separation crush amount and roll inclination angle. This pipe straightening method using a rotary straightener is characterized in that the amount of wear is predicted and the amount of offset, amount of crush, and roll inclination angle are set based on the predicted value.

Further, the roll wear amount may be predicted based on a predetermined relationship between the number of times of straightening the straightener and the roll wear amount. In addition, when setting the roll position and roll inclination angle, the amount of correction to those set values is memorized for each outer diameter, wall thickness, material, temperature, and roll center diameter of each stand. The offset amount, crush amount, and roll inclination angle are set by adding a correction term obtained by multiplying the corresponding correction amount by a predetermined coefficient according to the predicted value or actual measurement value of the center diameter.

[For use]

In the present invention, the amount of roll wear at the external contact point between the roll and the pipe is estimated from the amount of roll wear at the center of the roll, and the straightener setup is performed based on this, so the roll position and especially the roll inclination angle can be adjusted. You can increase the accuracy of settings. In addition, it is possible to use a method (hereinafter referred to as adaptive control) in which the amount of correction to the roll position and roll tilt angle setting values is reflected in the next roll position and roll tilt angle settings, allowing for more accurate settings. It becomes possible.

〔Example〕

Hereinafter, the present invention will be explained by taking a method of setting the roll inclination angle as an example.

Example 1 An example of a method for predicting the amount of roll wear at the outer contact point between the roll and the tube to be straightened will be described based on the amount of roll wear at the center of the tube.

FIG. 1 is an explanatory diagram showing a situation in which the roll is in contact with the pipe at a roll inclination angle θ. In the figure, (I) is a tube, which has an outer diameter d and is circumscribed with the roll (2) at a representative point of circumscription in the Z-axis direction Z'. Roll (2) center radius is R
Ov The distance on the roll axis between the center of the roll (2) and Z' is z, and the roll radius at z' is R. The roll inclination angle θ is determined by the geometric condition where the tube (1) and the roll (2) are circumscribed, taking into account the tube outer diameter d and the tube deflection V due to the offset δ0, that is, the curved surface f (x, y, z) = O
It is obtained from the following equation (1) (Yamura's equation) obtained from the condition that Equation 8 of the normal line % is the same for the roll curved surface and the pipe curved surface.

R= K ((Ro+d/2+v)/Cd/2+Ro
coS! θ)x (d/2+Rocos” θ)”
10 Zsin” θ-d/2) ・(1) However, V: Pipe deflection On the other hand, the amount of wear at the external contact point between the roll and the tube to be straightened is estimated from the amount of roll wear at the center of the roll as follows. That is, Fig. 2 is an example of a wear diagram of a roll for straightening medium-diameter pipes, and as can be inferred from the figure, the amount of roll wear at each position of the roll is approximated by a quadratic curve. As shown in FIG. 3, based on the roll wear ff1WRo at the roll center 0, the pipe 0 is
) and the roll wear amount Wz at the external contact point of the roll (2) is estimated.

In order to reflect the roll wear amount Wz estimated in this way in the setting of the roll inclination angle, set RWz instead of the roll radius R in Z' in the above equation (1), and calculate the roll inclination angle θ at that time. Bye.

In other words, the center of the roll is the origin of the two axes, and the representative point z'=
The roll radius when designing the roll at z is R= f (R
o, Te, ij, V, z), so R= R-W.

However, Ro: Roll center radius during roll design: 〃 Pipe radius θ: 〃 Roll inclination angle Ma:
〃 All you have to do is find θ, which is the deflection of the pipe.

Example 2 The amount of roll wear at the outer contact point between the O-ru and the tube to be straightened is predicted based on the number of straightenings of the straightener and the number of straighteners determined in advance for each of the outer diameter, wall thickness, material, and temperature at the time of straightening of the tube to be straightened. This can be done based on the relationship with the amount of roll wear at the center of the roll.

Fig. 4 is a diagram showing an example of the relationship between the number of times of straightening the straightener and the roll wear amount at the center of the roll.
This is a case of straightening a Cr-Mn steel pipe with a wall thickness of 12.57 mm and a thickness of 12.57 mm at 500°C. The amount of roll wear can be predicted from the number of times the straightener is straightened. Using this predicted value and the method described in Example 1, it is possible to predict the roll wear amount at the external contact point between the roll and the tube to be straightened.

Example 3 When setting the 0-roll inclination angle, the amount of correction to the set value of the roll inclination angle, that is, the amount of fine adjustment of the roll inclination angle with the pipe hooked to the straightener, is applied to the next roll inclination angle setting. Setting accuracy can be further improved by performing adaptive control to reflect the settings.

To explain this method using formulas, the outer diameter, wall thickness, material, temperature,
The long-term adaptive actual value of the roll inclination angle is calculated using the following formula (2) for each roll diameter category, and this is calculated using the following formula (3).
Add it to the calculated target roll inclination angle as a correction term according to the formula,
The following roll inclination angle is set. The calculated target roll inclination angle is the roll inclination angle determined by substituting R-W instead of the roll radius R in the above equation (1).

△θn (Lk) = △θn-t (i, k) +wx
Δθ(11-11A (r, k)...(2)θ
, (i, k) ”θ1l(5k)+△θ1l(i,k
) ・-・(3) However, △θn (i, k) Long-term adaptive actual value of lower roll inclination angle Δθn-1 (i, k
) : Previous adaptive actual value of roll inclination angle Δθ(.-11A (+, k) : Correction amount θ, l(i, k) for previous roll inclination angle set value (target °° roll inclination angle): Current roll inclination angle setting value (target roll inclination angle) θo (i, k): Current calculation target roll inclination angle W:
Adaptive gain i: stand consideration k: upper and lower rolls Note that good results can be obtained if the amount of correction is limited to the amount of correction when a good tube straightening result is obtained.

〔Effect of the invention〕

As explained above, in pipe straightening using a rotary straightener, the present invention predicts the amount of roll wear at the external contact point between the roll and the pipe to be straightened, and sets the roll position and roll inclination angle based on this predicted value. By applying this method, highly accurate setup settings can be performed. Also,
Setting accuracy can be further improved by calculating the correction amount for the set value of the roll inclination angle for each outer diameter, wall thickness, material, temperature, and roll diameter classification and reflecting it in the next setting.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the roll inclination angle setting method, Fig. 2 is a roll wear diagram showing an example of the roll wear situation, and Fig. 3 is the wear amount at the center of the roll at the outer contact point of the roll and the tube to be straightened. An explanatory diagram of a method for estimating the amount of wear, and FIG. 4 is a diagram showing an example of the relationship between the number of times of straightening the straightener and the amount of roll wear.
FIG. 6 is an explanatory diagram showing the state of tube straightening by the straightener. 1...Pipe 2...Roll 3...Pipe movement center axis diagram Saitzu slut force correction Memaki (mark) Low 1 and pull 3 Hi (electric)

Claims (3)

[Claims] (1) In the pipe straightening method using a rotary straightener, which is performed by setting appropriate offset amount, crush amount, and roll inclination angle, roll wear at the outer contact point of the roll and the straightened pipe is based on the roll wear amount at the center of the roll. 1. A method for straightening a pipe using a rotary straightener, which comprises predicting the amount and setting an offset amount, a crush amount, and a roll inclination angle based on the predicted value. (2) A pipe straightening method using a rotary straightener according to claim 1, wherein the prediction of roll wear amount is performed based on a relationship between a predetermined number of times of straightening the straightener and a roll wear amount at the center of the roll. (3) In the tube straightening method using a rotary straightener, which is performed by setting appropriate offset amount, crush amount, and roll inclination angle, the amount of correction for the set values of offset amount, crush amount, and roll inclination angle is The thickness, material, temperature, and roll center diameter of each stand are memorized, and at the next setting, the corresponding correction amount is multiplied by a predetermined coefficient according to the predicted value or actual measured value of the roll center diameter of each stand. A pipe straightening method using a rotary straightener, characterized in that an offset amount, a crush amount, and a roll inclination angle are set by adding terms.