JP3045070B2 - Manufacturing method of tapered plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a tapered plate having a plate thickness continuously changing in the longitudinal direction, and more particularly to a method for manufacturing a tapered plate having parallel portions at both ends having a uniform thickness in the longitudinal direction. About.

[0002]

2. Description of the Related Art When a steel sheet is used as a structural member, the required strength may differ from part to part. One of the steel plates used in such a case is a tapered steel plate. As shown in FIG. 3, this is a steel sheet whose thickness continuously changes from one end to the other end in the longitudinal direction, and is usually manufactured by multi-pass reversible rolling. As shown in FIG. 4, there is a type of tapered steel plate having parallel portions 1 and 3 having a uniform thickness at both ends and a tapered portion 2 formed therebetween, as shown in FIG. This tapered steel sheet is often manufactured by multi-pass reversible rolling, similarly to the tapered steel sheet of FIG.

In the production of a tapered steel sheet by multi-pass reversible rolling, a tapered portion is formed by continuously changing a roll gap during rolling. The pass schedule is basically determined by a constant volume condition regardless of whether or not parallel portions exist at both ends. Japanese Patent Application Laid-Open No. Sho 62-54504 discloses a taper rolling method for determining the schedule of each pass so that the rolling reaction force falls within an allowable shape range in order to improve the surface flatness of the tapered portion. However, the basic pass schedule is based on a constant volume condition.

[0004]

In the case of a tapered steel plate having parallel portions at both ends, the design of the pass schedule not only sets the maximum and minimum plate thicknesses in each pass, but also sets the tapered portion and the minimum thickness. Each length of the parallel part also needs to be scheduled. According to the condition of constant volume, when the maximum thickness and the minimum thickness are determined, the respective lengths of the tapered portion and the parallel portion of each pass can be obtained from the product dimensions after rolling as shown in the following formula (FIG. 4). reference).

L ₁ (i) = V ₁ / [h ₁ (i) · W] L ₂ (i) = 2 × V ₂ / ｛[h ₁ (i) + h ₂ (i)] · W｝ L ₃ (i) = V ₃ / [h ₂ (i) · W] L ₁ (i), L ₃ (i): Length of the parallel portion of the i-th pass L ₂ (i): Length of the tapered portion of the i-th pass Lengths h ₁ (i), h ₂ (i): minimum thickness and maximum thickness of the i-th pass V ₁ , V ₃ : volume of parallel part of product V ₂ : volume of taper part of product W: product width ( (Same width as each pass)

By the way, in actual rolling, scale loss,
Due to slab cutting errors and the like, the slab volume before rolling often does not match between the pass schedule and the actual rolling. If the slab volume has an error with respect to the pass schedule in the case of a tapered steel plate having parallel portions at both ends, FIG.
As shown in (A), the length L ₁ (i) ′ of the parallel part on the trailing edge side in actual rolling is the length L of the parallel part in the pass schedule.
An error of Le occurs for ₁ (i). This is because the excess or deficiency of the slab volume with respect to the pass schedule is absorbed by the variation in the length of the rolled material, and the variation in the length occurs in the parallel portion on the trailing edge side.

In the next pass, as shown in FIG. 5 (B), the parallel portion which was on the trailing side in the previous pass becomes the biting side. Therefore, when rolling is performed according to the pass schedule,
The roll gap change start point where the taper part starts to be formed is
Gs' shifted Le from Gs point in pass schedule
Points.

In the rolling of the tapered portion, the roll gap is uniformly changed from the change start point to the change end point in accordance with the pass schedule. An error also occurs in the outlet plate thickness. At present, the accumulation of these errors in the multi-pass rolling causes deterioration of the thickness accuracy.

It is an object of the present invention to provide a method of manufacturing a tapered plate capable of manufacturing a tapered plate having parallel portions at both ends with high plate thickness accuracy.

[0010]

According to the method of manufacturing a tapered plate of the present invention, when a tapered plate having parallel portions at both ends in the longitudinal direction is manufactured by multi-pass reversible rolling, i.
After the rolling of the pass, the length of the parallel portion on the side where the bottom was removed was actually measured, and in performing the pass schedule after the (i + 1) th pass, the target length of the parallel portion was calculated based on the measured length of the parallel portion. It is characterized by being modified.

[0011] In the method of the present invention, the length of the parallel portion of the side that Shirinuke to i pass is actually measured, the target length of the parallel portion is corrected, the roll gap change by the error L _e of the parallel portion The deviation of the starting point is eliminated, and the thickness variation of the tapered portion is suppressed.

In the method of the present invention, the length of the tapered portion is finished according to the product dimensions, but the length of the parallel portions at both ends is not the same as the product dimensions because its target value is changed. An excessive length of the parallel portion can be handled by truncation after rolling, but an insufficient length cannot be handled. Therefore, in the method of the present invention, at the stage of designing the product dimensions at the time of making the pass schedule, the product length of the parallel portion at both ends is estimated to be longer than the required value, and the shortage of the parallel portion in actual rolling is reduced. Care must be taken to prevent this from happening.

The actual measurement of the length of the parallel portion and the correction calculation of the target length based on the measured value may be performed for all passes from the first pass to the last pass to which the tapered portion is provided, or an arbitrary pass. May be performed an arbitrary number of times.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of correction calculation of a target length of a parallel portion in the method of the present invention. In the method of the present invention, a tapered steel sheet having parallel portions 1 and 3 at both ends in the longitudinal direction is manufactured by multi-pass reversible rolling. In the reversible rolling, the parallel portion on the side where the trailing edge was lost in the i-th rolling was i + 1
In the rolling of the pass, it is on the biting side.

In the method shown in FIG. 1, as shown in FIG. 1 (A), the length L ₁ (i) ′ of the parallel portion 1 on the trailing edge side is actually measured when the i-th rolling is completed. L ₁ (i) is the length of the parallel portion 1 on the pass schedule initially set. In actual rolling, as described above, an error often occurs between L ₁ (i) ′ and L ₁ (i) due to an error in the slab volume or the like. If the error is ignored and the initial pass schedule is performed, In addition, an error occurs in the thickness of the tapered portion 2.

[0017] Therefore, in this method, as shown in FIG. 1 (B), using the measured length L ₁ of the parallel part 1 (i) ', i + 1 pass of the parallel part 1 length L ₁ ( i + 1) is predicted and calculated, and this is set as the target length of the same parallel portion 1 in the (i + 1) th pass on the pass schedule. In the (i + 1) th pass, the parallel portion 1 is on the biting side.

The actual thickness of the parallel portion 1 of the i-th pass is represented by h
₁ (i), the target plate thickness of the parallel portion 1 in the (i + 1) th pass is defined as h ₁ (i +
1), the target length L ₁ of the same parallel portion 1 in the (i + 1) th pass
(i + 1) is as follows from a constant volume condition. L ₁ (i + 1) = L ₁ (i) ′ · h ₁ (i) / h ₁ (i + 1)

Further, as shown in FIG. 1C, using the target length L ₁ (i + 1) of the same parallel portion 1 at the (i + 1) th pass,
The length L ₁ (i + 2) of the same parallel portion 1 at the (i + 2) th pass is predicted and calculated, and this is set as the target length of the same parallel portion 1 at the (i + 2) th pass on the pass schedule. At the (i + 2) th pass, the parallel portion 1 returns to the trailing side.

The target thickness of the parallel portion 1 in the (i + 1) th pass is represented by h.
₁ (i + 1), the target plate thickness of the same parallel portion 1 in the (i + 2) th pass is h ₁
Assuming (i + 2), the target length L ₁ (i + 2) of the same parallel portion 1 in the (i + 2) th pass is as follows from a constant volume condition. L ₁ (i + 2) = L ₁ (i + 1) · h ₁ (i + 1) / h ₁ (i + 2)

In this way, based on the measured length of the parallel portion 1 of the i-th pass, the target length of the same parallel portion 1 on the path schedule up to the final pass is determined, and the original target length is set to this. change. Then, after the (i + 1) th pass, rolling is performed in accordance with the corrected pass schedule.

Basically, all errors in the slab volume and the like appear as errors in the length of the parallel portion 1 on the trailing edge side at the completion of rolling in the first pass. Therefore, if the target length of the same parallel portion 1 in the second and subsequent passes is corrected on the pass schedule based on the measured length of the same parallel portion 1 in the first pass, the roll gap due to errors in the slab volume and the like can be obtained. The deviation of the change start point is eliminated, and the thickness error of the tapered portion 2 due to this is removed.

It is also possible to leave the length error of the parallel portion up to an intermediate path and correct the target length from the intermediate path. Errors in the slab volume and the like also appear as an error in the length of the parallel part on the trailing edge side in the middle of the pass.Therefore, based on the measured length of the parallel part on the trailing edge side, modify the path schedule for subsequent passes. Do. However, it goes without saying that performing the correction operation from the first pass improves the thickness accuracy of the tapered portion.

FIG. 2 is a block diagram of a rolling facility suitable for carrying out the method of the present invention. The rolling mill 10 includes a pair of upper and lower work rolls 10a, 10a and a backup roll 10
b, 10b, the material to be rolled W is alternately rolled a plurality of times in the forward and reverse directions, and a rolling device 12 having a hydraulic cylinder is controlled in each pass, so that a tapered steel plate having parallel portions at both ends. To manufacture.

During rolling, the rolling position is detected by the rolling position detector 13. The rolling load detector 14 detects the rolling load, and the pulse generator 15 connected to the work roll 10a detects the longitudinal position of the material W to be rolled. Then, with respect to the entire length of the material W to be rolled, the target roll gap is sequentially given from the target roll gap setting device 20 to the rolling position control system 21 so that the actual roll gap obtained from the detected value of the rolling position matches the target roll gap. Then, the rolling-down device 12 is controlled by the rolling-down position control system 21. Then, the target roll gap for the entire length of the material to be rolled W is determined here as follows.

A pass schedule set in advance for the material to be rolled W is given to a pass schedule setting unit 16. The pass scheduler 16 gives the target thickness at the material longitudinal position in each pass to the target thickness setter 17 based on the given pass schedule. Target thickness setting device 1
7 corrects the length of the parallel portion based on the calculation result of the length of the parallel portion given from the length calculator 18, resets the target plate thickness at the longitudinal position, and sets the target roll gap setting device 20 to the target roll gap setting device 20. give.

The length calculator 18 calculates the pressure extension of the previous path detected by the pulse generator 15 on the basis of the actual result (the length of the parallel portion on the trailing edge side) of the current path on the biting side of the current path. The length and the length of the parallel portion on the trailing edge side of the next pass are calculated and given to the target thickness setting device 17. As described above, the target thickness setting device 17 corrects the length of the parallel portion based on the calculation result, resets the target thickness at the longitudinal position based on this, and sets the target roll gap setting device 20 to the target roll gap setting device 20. give. Then, the target roll gap setting device 20 determines the roll gap based on the target plate thickness and the rolling load at the longitudinal position.

Using this equipment, the plate width 228 is corrected by a method of correcting the target length of the parallel portion for all passes after the second pass based on the actually measured length of the parallel portion on the trailing edge side of the first pass.
3mm, thickness 18 / 24mm, parallel part length 1000 + 10
1 mm taper steel plate with a taper length of 10,000 mm
0 sheets were rolled, and the difference between the measured thickness and the target thickness at each point in the longitudinal direction of the tapered portion was investigated. As a result, the thickness error of the tapered portion was less than 100 μm in the conventional method, but was less than 30 μm in the present method, and it was confirmed that the thickness accuracy of the tapered portion was greatly improved.

[0029]

As described above, the method of manufacturing a tapered plate according to the present invention is applicable to a method of manufacturing a tapered plate having parallel portions at both ends in the longitudinal direction by performing a multi-pass reversible rolling. After the actual measurement of the length of the parallel portion on the side where the hips were lost, and in performing the pass schedule after the (i + 1) th pass, by correcting the target length of the parallel portion based on the actually measured length of the parallel portion Since the deviation of the roll gap change start point due to the error of the slab volume and the like is eliminated, the thickness variation of the tapered portion due to this can be suppressed,
It has a great effect on improving the dimensional accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of correcting a target length of a parallel portion in the method of the present invention.

FIG. 2 is a configuration diagram of a rolling facility suitable for carrying out the method of the present invention.

FIG. 3 is a schematic view showing the shape of a tapered steel plate.

FIG. 4 is a schematic view showing the shape of a tapered steel plate having parallel portions at both ends.

FIG. 5 is a schematic view showing a length error of a parallel portion and a shift of a roll gap change start point due to the length error.

[Explanation of symbols]

 1, 3 parallel portion 2 taper portion 10 rolling mill 12 rolling device 13 rolling position detector 14 rolling load detector 15 pulse generator

Claims (1)

(57) [Claims] When producing a tapered plate having parallel portions at both ends in the longitudinal direction by multi-pass reversible rolling, i.
After the rolling of the pass, the length of the parallel portion on the side where the bottom was removed was actually measured, and in performing the pass schedule after the (i + 1) th pass, the target length of the parallel portion was calculated based on the measured length of the parallel portion. A method for manufacturing a tapered plate, wherein the method is modified.