JPH0890068A - Equipment and method for straightening steel strip for spiral steel tube making - Google Patents

Abstract

PURPOSE: To improve the working efficiency of manufacturing a spiral tube by straightening not only the chamber part of the steel strip to be used for manufacturing the spiral steel tube but also the defective angle of connection of the joining part of the steel strip to straighten the steel strip. CONSTITUTION: Two pairs of pinch rolls 2, 4 to apply the tension to the steel strip are provided on the inlet side of a spiral steel tube making machine 1, and a leveler 3 to provide the bending and tensile deformation to the steel strip is provided between the pinch rolls. The leveler 3 and the pinch rolls 2, 4 on the inlet side and the outlet side are provided on the inlet side of the spiral steel tube making machine, and the bending and tensile deformation by the leveler 3 is given to the steel strip while the tension is applied to the steel strip between the pinch rolls to straighten the chamber of the steel strip and/or the defective angle of connection of the steel strip joining part. In this method, the displacement of the steel strip in the width direction is detected, and the mean plastic elongation of the difference Δε in the elongation ratio or more at each end part of the steel strip is given to the steel strip to straighten the camber or the defective angle of connection, and more preferably, the right and left reduction balance of the work rolls of the leveler is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for correcting a camber of a steel strip for a spiral steel pipe material used for spiral pipe forming and a defective connection angle by a leveler provided on the inlet side of the pipe forming machine, and a correction using the same. Regarding the method.

[0002]

2. Description of the Related Art In spiral pipe manufacturing, defects in a steel strip as a raw material have a great influence on the shape and quality of the spiral steel pipe of a product, and in particular, the product shape is appropriately determined by bending a steel strip called a camber. In addition to being unable to obtain, it causes various defects in the weld.

In order to avoid the occurrence of the camber of the steel strip, the camber is prevented by adjusting the amount of reduction in the width direction of the strip in the rolling mill in the hot rolling for manufacturing the steel strip.
However, the actual rolling speed is about 600 m / min for thick material (about 10 mm thickness) and 1000 m / min or more for thin material. In addition, lateral deviation of hot rolling mill constant, off-center of side guide and edger, slab There are various causes of camber such as temperature deviation in the width direction, rattle between chocks, improper leveling, and error in coil winding.Because it has to be judged visually, it is used for spiral pipe making. The current situation is that the camber of steel strip for spiral steel pipe material cannot be controlled below a certain level.

Therefore, in the spiral pipe making, the camber of the steel strip is adjusted by the gap control at the time of pipe making, and the camber material is subjected to the outer diameter adjustment to make the shape good. However, there is a limit on its own, and there are changes in the outer diameter, steps, and too much separation of the base metal edges at the weld.

The following measures have been taken as means for solving such problems, but each has its own problems.

Japanese Patent Publication No. 37-3459 discloses a technique for controlling excessive edge pressure generation at the time of welding in spiral pipe forming equipment. This is due to the shape caused by the camber of the material coil that has already occurred. It does not eliminate defects.

In Japanese Patent Laid-Open No. 59-85302, the end of the steel strip in the longitudinal direction is manufactured wider than the center of the steel strip so as to allow a camber of a predetermined length from the end of the steel strip in the longitudinal direction. In a pipe forming machine, a method of trimming a wide part after welding and connection with the next coil is disclosed.In order to roll into such a shape, the part corresponding to the end of the steel strip is widened from the slab stage. It is necessary and difficult. Further, only the camber near the end of the steel strip can be dealt with, and the camber at the center of the steel strip cannot be dealt with.

JP-A-54-162665 discloses a camber amount detector and a rolling mill disposed on the inlet side of a pipe making machine, and controls the left and right rolling reductions of the rolling mill based on the detected camber amount to correct the camber. However, complicated control is required. Further, it is not suitable for adjusting a minute camber amount of several cm or less per 10 m.

Japanese Unexamined Patent Publication (Kokai) No. 1-176764 discloses a method of straightening a camber by installing a tension leveler on a thin metal strip such as continuous annealing, but it is a thick material used as a material for spiral pipes. It is necessary to apply a sufficient tension to the correction of the above, and for that purpose, the device becomes large and unsuitable.

If there is a camber in the steel strip for spiral steel pipe material, it becomes the main cause of the gap and outer diameter variation during welding and the offset of the abutting portion, and the line speed is lowered due to such adjustment.

In a general spiral pipe forming apparatus, a roller leveler is installed on the inlet side of the pipe making machine to remove the winding habit (warp in the longitudinal direction) of the steel strip unwound by the uncoiler. The warp can be removed by repeated bending, but the camber of the steel strip cannot be corrected.

[0012]

The camber of the steel strip for spiral steel pipe material is the main cause of the gap and outer diameter variation during welding and the offset of the abutting portion, and the dimensional accuracy is reduced due to the outer diameter variation of the spiral steel pipe. In addition, the line speed of the pipe making equipment is reduced due to the adjustment and the like, so that the work efficiency is reduced. Moreover, the camber amount is large near the longitudinal ends of the steel strips, and a poor connection angle occurs during the welding connection between the steel strips, so the accuracy of the spiral pipe deteriorates due to gaps and outer diameter fluctuations during pipe making welding. Productivity is also reduced.

The yield is reduced only by increasing the edge trim margin as a measure against bending and defective welding angle.
Also, a small connection angle defect can be removed by trimming, but when trimming a steel strip with a camber, the trim is performed along the camber which is a bend of the steel strip,
The camber cannot be removed by trimming. Furthermore, by preventing the camber of the base material, it is possible to improve the accuracy and productivity of the spiral pipe, but in the normal rolling line, the line tension is not applied near the longitudinal end of the steel strip, It is difficult to prevent the camber, and the camber of the steel strip becomes particularly large near the longitudinal end of the steel strip.Therefore, after welding the steel strip, not only the camber portion of the steel strip, but also the connection portion of the steel strip. There are still problems such as the need to correct it.

To solve the above problems, the steel strip is straightened by correcting not only the camber portion of the steel strip used for producing the spiral steel pipe but also the defective connection angle of the steel strip connection portion, There has been a demand for the development of a straightening device and a straightening method which can improve the working efficiency of spiral pipe making and are inexpensive.

[0015]

Means for Solving the Problems To solve the problems of the camber of the steel strip and the poor connection angle of the steel strip at the time of spiral pipe making, the inventors of the present invention have solved the problems such as the camber of the steel strip and the defective connection portion before the spiral pipe making. As a result of various studies on the method of correcting
The following findings were obtained.

In order to correct the camber of the steel strip, the camber can be corrected by giving an average plasticity stretch equal to or greater than the difference in elongation between both ends of the strip width of the steel strip corresponding to the amount of camber of the steel strip.

In order to correct the poor connection angle of the steel strip, the camber amount equivalent to the poor connection angle of the steel strip is determined,
Corresponding to that, by giving an average plasticity stretch equal to or more than the difference in elongation between both ends of the strip width of the steel strip, the defective connection angle of the steel strip can be corrected.

To prevent the steel strip from slipping between the rolls, pinch rolls are provided on the inlet and outlet sides of the leveler, and while the tension is applied to the steel strip by the pinch roll and the uncoiler, the leveler is provided between the pinch rolls to the steel strip. The above plastic elongation can be given by giving bending tensile deformation. Furthermore, the tension between the pinch rolls and the amount of intermesh (offset amount of the upper and lower rolls of the leveler) depending on the camber amount and / or the connection failure angle based on the detection result of the steel strip shape detection device, and the work roll of the leveler It is possible to more accurately correct the camber of the steel strip and / or the defective connection angle of the steel strip by changing the left-right reduction balance.

According to the present invention, two pairs of pinch rolls for applying tension to the steel strip are provided on the inlet side of the spiral pipe forming machine,
It is a straightening device for a steel strip for a spiral steel pipe material, in which a leveler is provided between the pinch rolls to bend and stretch the steel strip.

In another embodiment, a leveler and pinch rolls on the inlet side and the outlet side of the leveler are provided on the inlet side of the spiral pipe forming machine, and bending is performed by the leveler while applying tension to the steel strip between the pinch rolls. It is a method of straightening a steel strip for a spiral steel pipe material, in which tensile deformation is applied to correct a camber of a steel strip and / or a defective connection angle of a steel strip connection portion.

Further, the amount of camber of the steel strip is detected by the shape detecting device for the steel strip provided on the inlet side and / or the outlet side of the leveler, and the leveler determines the average plastic stretch of Δε _C or more of the following formula (1). It is a method of straightening a steel strip for a spiral steel pipe material, which is applied to a strip to straighten the camber.

Δε _C = (8δw) / L ² (1) where Δε _{C is the} difference in elongation between both ends of the plate width corresponding to the amount of camber of the steel strip, and δ is the amount of camber at the reference length L ( mm), w: plate width (mm), L: reference length (mm).

Further, the connection failure angle of the steel strip is detected by a steel strip shape detecting device provided on the inlet side and / or the outlet side of the leveler, and the leveler measures the average plastic stretch of Δε _J or more in the following equation (2). It is a method of straightening a steel strip for a spiral steel pipe material, which is applied to a strip to correct a defective connection angle.

Δε _J = (1/3) × tan (θ / 2) (2) where Δε _{J is the} difference in elongation between both ends of the strip width corresponding to the displacement of the connection angle failure of the steel strip, θ: It is the connection failure angle (degree) of the steel strip connection portion.

More preferably, in addition to the straightening by the leveler, the left and right reduction balances of the work rolls of the leveler are changed according to the amount of camber and / or the connection failure angle to connect the camber and / or the steel strip. This is a method of correcting a steel strip for a spiral steel pipe material, which corrects an angle defect.

[0026]

According to the present invention, tension is generated between the pinch rolls provided on the inlet side and the outlet side of the leveler, and a plastic stretch corresponding to a camber is imparted to the steel strip by repeated bending by the leveler, whereby the camber or the steel strip of the steel strip is provided. This is to correct the defective connection angle portion of the belt and straighten it.

The thick hot-rolled steel strip used as the material for the spiral steel pipe requires a large size device to generate the tension by the bridle roll like the tension leveler applied to the thin steel strip. Therefore, in the present invention, tension is generated by providing pinch rolls having high rigidity in front of and behind the leveler so as to act as a bridle roll of a thin steel strip.

FIG. 1 shows a device configuration according to the present invention. A straightening device is provided on the inlet side of the spiral pipe forming machine 1, a front tension is applied to the steel strip by a pinch roll 2 provided on the outlet side of the leveler 3, and a rear tension is applied by a pinch roll 4 and an uncoiler 5 on the leveler inlet side. Tension is generated between the pinch rolls 2 and 4 by giving it to the steel strip, and plastic tension can be given by repeatedly giving bending tension to the steel strip with the leveler 3 while giving the tension.

FIG. 5 shows a mechanism in which a steel strip is repeatedly bent and stretched by a leveler to give plastic stretch. In this figure, the leveler is composed of five rolls, two upper rolls and three lower rolls. The upper roll and the lower roll are arranged at a specific roll pitch. Plastic elongation is imparted to the steel strip by passing the steel strip alternately through the upper roll and the lower roll in which the amount of intermesh (the distance between the lower face of the upper roll and the upper face of the lower roll) is adjusted.

When the steel strip has a camber, the concave side of the camber has a higher tension than the convex side on the leveler entry side,
The leveler causes a larger plastic stretch on the concave side than on the convex side, which reduces the camber. Therefore, if a leveler is used to give the steel strip a sufficient plastic stretch that is equal to or more than the difference in elongation between the widthwise ends of the camber material, the steel strip can be straightened.

FIG. 6 is a diagram showing a camber of a steel strip. The difference in elongation rate Δε at both ends of the strip width of the steel strip having the camber.
_C has a relationship with the camber amount δ according to the following equation (1).

Δε _C = (8δw) / L ² (1) Δε _C : Difference in elongation between both ends of the plate width corresponding to the amount of camber of the steel strip, δ: amount of camber at the reference length L (mm) w : Plate width (mm) L: Reference length (mm) The camber can be corrected by giving the steel strip an average plastic elongation of Δε _C or more. For example, with a board width of 1000 mm, per 10 m
In the case of a plate with a camber of 20 mm, the average plastic spread to be given is 0.16% or more.

When the steel strip connection portion has a poor connection angle, the concave side with a poor connection angle on the leveler entry side has a higher tension than the convex side, and the leveler causes a greater plastic spread on the concave side than on the convex side. Occurs, and the difference in length between both ends of the plate width is reduced. Therefore, if the leveler considers a camber equivalent to a poor connection angle of the steel strip, and the steel strip is provided with a sufficient plasticity stretch equal to or more than the difference in elongation between both ends of the strip width, the steel strip can be straightened.

FIG. 7 is a diagram showing a defective connection angle of the steel strip. In this portion, when the displacement amount with respect to the reference length L is X and the defective connection angle is θ, X / (L / 2) = Tan (θ / 2)
It is represented by. In this case, when the width of the steel strip is w, the convex side is longer than the concave side by (2w × tan (θ / 2)), and if the plastic elongation is given to eliminate this difference, the welding angle defect is corrected. it can.

In order to confirm the difference in correction effect between a normal camber material and a material having a bad connection angle, a steel strip having a thickness of 14 mm and a width of 935 mm was used with a material having a poor connection angle with a displacement of 10 mm with respect to a reference length of 10 m. The distribution of the longitudinal elongation of the steel strip in the width direction after passing through the leveler was measured by the scribing line method. The results are shown in Fig. 8. The plastic spread is distributed so as to cancel the difference in length at both ends of the plate width due to the poor connection angle, and the uneven plastic spread is obtained in the width direction. It was confirmed that the distance was about three times.

That is, when a material with a poor connection angle is straightened by a leveler, uneven plastic stretch in the width direction is obtained in the range of about 3 times the width of the plate, so that the elongation at both ends of the width of the plate is increased. The rate difference Δε _J is (2w × tan (θ / 2)) / 6w, and
If an average plasticity spread equal to or more than the elongation difference Δε _J expressed by equation (2) is given, the welding angle defect is corrected.

Δε _J = (1/3) × tan (θ / 2) (2) Δε _J : Difference in elongation rate between both ends of the strip width corresponding to the displacement amount due to poor connection angle of steel strip θ: Steel strip connection portion Misconnection angle (degree) Further, by increasing the reduction amount of the work roll of the leveler from the convex side to the concave side, a greater plastic stretch is given to the concave side compared to the case where the same reduction amount is left and right. Can
The tension for giving the same correction amount is reduced, and the equipment can be downsized.

FIG. 2 shows another device configuration of the present invention.
Steel strip shape detector (camber detector) on the leveler exit side 6
Is provided to detect the camber amount and the connection failure angle, and feed back the detection results to the control panel 7 for tension between the pinch rolls and intermesh amount (pushing amount of the upper and lower work rolls of the leveler). The elongation difference Δε _{C at} both ends of the strip width of the steel strip is controlled by controlling the left and right rolling amount.
By providing the steel strip with an elongation of Δε _J or more, the straightening can be performed more effectively.

FIG. 3 shows still another apparatus configuration of the present invention. A steel strip shape detection device (camber detector) 6 is installed on the leveler entrance side, and the detection result is fed forward to control the tension. It is also possible to control the amount of horizontal reduction of the leveler work roll and the leveler work roll. Furthermore, a steel strip shape detection device (camber detector) 6 is installed on both the leveler input side and output side, and the leveler work roll is detected by both detection values. By controlling the amount of lateral reduction and the like, it is possible to correct the camber with higher accuracy.

When controlling the straightening of the steel strip by using the apparatus configuration of FIG. 2, as shown in the flowchart of FIG. 9, the camber amount or the plate width direction displacement amount is continuously detected, and the camber or By controlling the pushing amount of the work roll of the leveler so as to eliminate the defective connection angle, the camber and the defective connection angle can be eliminated.

As the shape detecting device (camber detector) 6, for example, the steel strip edge position is measured at three points using a sensor, and the camber amount and the displacement amount due to a defective connection angle are measured from the relative positions of the detection points. There are a method, a method of detecting from the measured value of the tension distribution of the steel strip using a shape meter, etc., and a method of detecting from the difference in the load applied to both ends of the roll of the tensiometer using three rolls.

Further, it is easy to detect the amount of camber in a portion having a large camber, such as in the vicinity of the longitudinal end of the steel strip, and not only the above-mentioned tension control on the leveler input / output side and control of the intermesh amount, but also camber detection. Unbalanced reduction, which changes the left and right reduction amount of the leveler work roll based on the value, is effective.

Further, since the pinch rolls provided on the inlet side and the outlet side of the leveler control the tension on the inlet side and the outlet side of the leveler, if there is a slip between the steel strip and the roll, the tension cannot be reliably transmitted. It is necessary to secure a sufficient roll reduction amount to press the roll against the steel strip. For that purpose, it is also effective to provide a plurality of pinch rolls provided on the inlet side and the outlet side of the leveler as shown in FIG.

Usually, the spiral pipe forming equipment is provided with a roller leveler for removing longitudinal warp (rolling tendency), and if the rigidity of this leveler is sufficient, slip between the roll and the steel strip can be prevented. In addition, inexpensive capital investment such as installation and reinforcement of pinch rolls with sufficient rolling force on the inlet and outlet sides of the leveler will be sufficient.

[0045]

【Example】

 (Example 1) First, a straightening test was performed on a thick hot-rolled steel strip.

Using the apparatus having the configuration shown in FIG. 1 and the specifications shown in Table 1, the correction effect was confirmed.

Table 2 shows the test conditions and results. It was confirmed that with the specifications of this facility, elongation can be imparted to the steel strip by applying tension even to thick hot-rolled steel sheets.

[0048]

[Table 1]

[0049]

[Table 2]

(Example 2) Further, in order to confirm the effects of correcting the camber and the welding angle defect in the thick hot-rolled steel strip, a camber member as shown in FIG. 6 and a connection angle defective member as shown in FIG. 7 were manufactured. , The camber correction effect was confirmed.

The yield point of the steel strip used was 30 kgf / mm ² , and the equipment specifications were the same as in Table 1.

Table 3 shows the test conditions of the camber material and changes in the camber amount before and after straightening. It can be seen that the camber is corrected by giving an average plastic elongation that is equal to or greater than the elongation difference Δε _C of both edges obtained from Eq. (1).

Table 4 shows the change in the displacement in the width direction before and after the correction of the connection angle defect. Poor connection angles could be corrected by giving a plastic stretch over the elongation difference Δε _J obtained from Eq. (2), and the required trim amount could be greatly reduced.

[0054]

[Table 3]

[0055]

[Table 4]

(Embodiment 3) Using the apparatus having the configuration shown in FIG. 2, a steel strip shape detecting device (camber detector) 6 is provided on the leveler output side, and based on the detection result, the control panel 7 enters the leveler input side. The tension on the delivery side and the amount of reduction on the left and right of the leveler work roll were controlled. Table 5 shows the test conditions and test results. The dimensions of the steel strip used are 10 mm thick and 500 mm wide, the yield point is 30 kgf / mm ² , and the equipment specifications are the same as in Table 1.

The camber can be corrected by giving plastic stretch with the leveler without any particular control, but in order to further enhance the effect, a camber detector is provided on the leveler entrance side and the leveler work roll is adjusted according to the camber amount. It was possible to correct by lowering the tension and rolling force by changing the rolling amount on the left and right.

[0058]

[Table 5]

Further, a test was conducted in which the straightening amount was controlled by a test steel strip in which the camber amount was continuously changed in the longitudinal direction of the steel strip. In the apparatus configuration in which a camber detector is provided on the exit side of the leveler in FIG. 2, the camber is corrected by controlling the pushing amount (intermesh amount) of the work roll of the leveler so that the camber is eliminated as shown in the flowchart in FIG. .

The results are shown in FIG. 10. The camber amount of the steel strip was 6 to 24 mm before straightening, but ± 1 after straightening.
The camber amount was within mm, and the steel strip was surely corrected in all the longitudinal direction of the steel strip.

[0061]

[Effects of the Invention] By applying tension between the pinch rolls on the inlet side and the outlet side of the spiral pipe forming machine, bending and tensile deformation are applied by the leveler, and plastic stretch is imparted to the steel strip. It became possible to correct the connection angle defect of the camber and the steel strip including the vicinity of the end in the longitudinal direction, and it was possible to improve the spiral pipe forming accuracy and production efficiency. Further, the trim amount of the defective welding angle portion can be reduced and the yield can be improved. Furthermore, by controlling the left and right reduction amount of the leveler work roll in combination with the shape detection device for the steel strip, the straightening effect can be enhanced and the equipment can be downsized.

[Brief description of drawings]

FIG. 1 is a diagram showing a device configuration of the present invention.

FIG. 2 is a diagram showing another device configuration of the present invention.

FIG. 3 is a diagram showing another device configuration of the present invention.

FIG. 4 is a diagram showing another device configuration of the present invention.

FIG. 5 is a diagram illustrating a mechanism for imparting plastic elongation to a steel strip by a leveler.

FIG. 6 is a diagram illustrating a camber of a steel strip.

FIG. 7 is a diagram for explaining a defective welding angle of a steel strip.

FIG. 8 is a diagram showing a change in elongation amount when a material having a poor connection angle of a steel strip is corrected.

FIG. 9 is a flow chart for controlling the pushing amount of the leveler work roll from the output of the steel strip shape detection device (camber detector) using the device of the present invention.

FIG. 10 is a diagram showing a test result of controlling the leveler work roll by feeding back the continuously detected camber amount using the device of the present invention.

[Explanation of symbols]

 1: Spiral pipe forming machine 2, 4: Pinch roll 3: Leveler 5: Uncoiler 6: Steel strip shape detection device (camber detector) 7: Control panel

Claims (5)

[Claims] 1. A spiral pipe forming machine is provided with two pairs of pinch rolls for applying tension to a steel strip, and a leveler for bending and tensile deformation of the steel strip is provided between the pinch rolls. Straightening device for steel strip for spiral steel pipe material. 2. A leveler is provided on the inlet side of the spiral pipe forming machine, and pinch rolls are provided on the inlet side and the outlet side of the leveler, and bending tension is applied by the leveler while applying tension to the steel strip between the pinch rolls. A method for straightening a steel strip for a spiral steel pipe material, which comprises straightening a camber of a steel strip and / or a defective connection angle of a steel strip connecting portion. 3. A method for straightening a steel strip for a spiral steel pipe material according to claim 2, wherein the amount of camber of the steel strip is detected by a steel strip shape detecting device provided at the leveler inlet side and / or outlet side. A straightening method of a steel strip for a spiral steel pipe material, which comprises applying an average plastic strain of Δε _C or more of the following formula (1) to the steel strip with a leveler to straighten the camber. Δε _C = (8δw) / L ² (1) where Δε _{C is the} difference in elongation between both ends of the plate width corresponding to the amount of camber of the steel strip, δ is the amount of camber at the reference length L (mm), w : Plate width (mm), L: Reference length (mm). 4. The method for straightening a steel strip for a spiral steel pipe material according to claim 2, wherein a steel strip shape detecting device provided on the leveler inlet side and / or the outlet side detects a poor connection angle of the steel strip. A straightening method for a steel strip for a spiral steel pipe material, which comprises straightening a connection angle defect by applying an average plastic stretch of Δε _J or more in the following formula (2) to the steel strip with a leveler. Δε _J = (1/3) × tan (θ / 2) (2) where Δε _{J is the} difference in elongation between both ends of the strip width corresponding to the displacement of the steel strip connection angle failure, θ is the steel strip connection Is the connection failure angle (degree) of the part. 5. A method of straightening a steel strip for a spiral steel pipe material according to any one of claims 2 to 4, wherein the work roll of the leveler is left-right balanced depending on the camber amount and / or the connection failure angle. Change the steel strip camber and /
Alternatively, a method for straightening a steel strip for a spiral steel pipe material, which comprises correcting a defective connection angle of the steel strip.