JPH01143706A - Rolling method - Google Patents

Abstract

PURPOSE:To maintain a good flatness by making up an intermediate target pass thickness part of a flat sheet of two kinds of the max. and the min thickness of a value internally divided by an interior division ratio of the intermediate thickness to the max. and the min target thickness in a product of metallic sheet. CONSTITUTION:Regarding the max. and the min thickness part of a sheet material variable in thickness, a rolling pass schedule of the flat sheet having this sheet thickness is applied and distortions in each part are restrained under generation limit of distorted wave. Regarding the intermediate thickness part of the max. and the min thickness part, the target pass thickness in each pass is given by the interior division of the max. and the min thickness part. Accordingly, the rolling reduction in each pass, too, is given by the interior division of the rolling reduction at the max. thickness part and the rolling reduction at the min thickness part, and the rolling reaction, too, is given nearly by the interior division of the reaction at the max. thickness part and the reaction at the min thickness. Accordingly, a sheet free from distortion and excellent in flatness can be obtained.

Description

[Detailed Description of the Invention] (Industrial Application Field) When using a metal plate as a structural member, there are many cases in which the required strength differs depending on the part, and in such cases, a plate whose thickness changes partially is used. may be required.

Specifically, such metal plate products with variable thickness are shown in Figure 3 (
As shown in a) to (c), the corrugated plate (
There are a), a tapered plate (b) whose thickness changes in an inclined manner, and a differential thickness plate (e) which is a shape in which flat plates of different thicknesses are connected.0
The present invention relates to a method of rolling a plate whose thickness changes in an arbitrary pattern, including the above-mentioned various plates.

(Prior art) The operation of a rolling device in rolling a metal plate product with variable thickness (hereinafter simply referred to as variable thickness material) is described, for example, in Japanese Patent Publication No. 46-1989.
As described in Japanese Patent No. 37086, a control method is adopted in which the gap between the rolls is sequentially changed from the rolling biting position only in the final pass. However, this method does not give any consideration to the effect on the flatness of the rolled material.

(Problems to be Solved by the Invention) Normally, when a material with variable thickness is manufactured by rolling from a material having the same thickness in the longitudinal direction, distortion occurs in the rolled material during the pass that changes the thickness. When the generation of this strain is severe, waves at the center of the rolled material called medium waves and waves at the edges of the rolled material called ear waves are formed, and as a result, the rolled material with variable thickness is attached. This results in a poor flatness.

The present invention provides a rolling method that can maintain good flatness when rolling a material with variable thickness.

(Means for Solving Problems and Problems) The present invention provides: (1) In manufacturing a metal plate product whose thickness changes in the longitudinal direction by rolling a material having the same thickness in the longitudinal direction, the metal plate is rolled in advance. Rolling of a flat plate whose maximum thickness is the flat plate product thickness and a flat plate whose minimum thickness among the metal plate products is the flat plate product thickness, starting from a material with the above-mentioned thickness and finishing with the same number of passes. Create a pass schedule, and when rolling the material for the metal sheet product,
The target pass thickness of the maximum thickness part in each pass is the target pass thickness of the pass schedule for the maximum thickness flat plate above, the target pass thickness of the minimum thickness part is the target pass thickness of the pass schedule for the minimum thickness flat plate above, and the intermediate thickness is Rolling according to a rolling pass schedule in which the target pass thickness of the two types of flat plates is internally divided by the internal division ratio of the intermediate thickness to the maximum target thickness and minimum target thickness in the metal sheet product. This rolling method is characterized by:

(2) In the rolling method of (1) above, the rolling pass schedule for the minimum thickness flat plate is the limit V that can maintain the flatness of the minimum thickness flat plate! In this paper, we adopted a schedule in which the amount of reduction per pass was increased, and created a schedule in which the amount of reduction per pass was reduced to the limit that could maintain the flatness of the maximum thickness flat plate as the rolling pass schedule for the maximum thickness flat plate. , the first pass in which the target pass thickness of the rolling pass schedule for the minimum thickness flat plate exceeds the target pass thickness of the rolling pass schedule for the maximum thickness flat plate among the passes in the same order in reverse order from the last pass of the above two types of rolling pass schedules. Then, modify the rolling pass schedule of the maximum thickness flat plate so that the target pass thickness of the rolling pass schedule of the maximum thickness flat plate in that pass matches the target pass thickness of the rolling pass schedule of the minimum thickness flat plate in the same pass, and then On the first pass side, the same rolling pass schedule as the minimum thickness flat plate is adopted as the maximum thickness flat plate rolling pass schedule, (
3) In the rolling method described in (2) above, check whether the flatness of the flat plate can be maintained according to the rolling pass schedule for the maximum thickness flat plate, and if it is not possible, repeat the first pass calculated above one by one. Checking the flatness while changing the pass on the pass side, and correcting the rolling bus schedule of the maximum thickness flat plate up to the pass that is acceptable, (4) (1) above.
In the rolling methods of , (2), and (3), a rolling pass schedule for a plurality of flat plates is created in which the thickness between the maximum thickness and the minimum thickness in the metal plate product is used as the flat plate product thickness, and the rolling pass schedule of the metal plate product is It is preferable to create the rolling pass schedule of the intermediate thickness part using an internal division ratio from the rolling pass schedule of two flat plates having the target thickness of the intermediate thickness part of the metal sheet product and the target thickness sandwiching it.

(Function) Regarding the rolling of a so-called flat plate with the same thickness in the direction of hand force, there is conventional knowledge that it is difficult to roll a flat plate, and it is easy to create a rolling pass schedule for rolling it flatly. For the maximum thickness section and minimum thickness section of the material, apply the rolling pass schedule for a flat plate with the same thickness to keep the strain at each section below the wave generation limit. By giving the target pass thickness in each pass by internally dividing the maximum thickness part and the minimum thickness part for the intermediate thickness part of the part, the reduction amount in each pass can also be calculated by dividing the reduction amount in the maximum thickness part and the reduction amount in the minimum thickness part. Since it is an internal division, the rolling reaction force is also an internal division of the reaction force at the maximum thickness part and the reaction force at the minimum thickness part.Furthermore, the rolling pass schedule for rolling flat plates of the same width and different thickness with good flatness is If such a rolling pass schedule is used, in which both the exit side plate thickness and the reaction force in each pass are internally divided at the same ratio, a flat plate with good flatness and an intermediate thickness can be obtained.

Therefore, according to the rolling pass schedule for the plate thickness-variable material in the method of the present invention, a plate with good flatness can be obtained while suppressing distortion even in the open thick part. Furthermore, by using the method (2) above, it is possible to reduce the number of passes in which the roll gap is changed during rolling passes, thereby improving productivity.

(Example) Embodiments of the present invention will be described with reference to FIGS. 1 to #3.

As a method for creating a flat plate rolling pass schedule, plate crown percentage constant rolling proposed by Tanabe et al. (Taneben and Misaka: Plasticity and Processing, 1B-168, (1975), 1o) is used. In this method, the rolling reaction force of each rolling pass is Fi=αH
i β β ... (1) Fi: i pass rolling reaction force Hi * i pass exit plate thickness α: Coefficient that determines plate crown β: Coefficient that determines shape When creating a rolling pass schedule for a flat plate, use the above theory. Depending on how the values of a and β are taken, there is a rolling pass schedule in which the rolling reaction force in the finishing pass is relatively large (hereinafter referred to as the "strong rolling pass schedule") and a rolling pass schedule in which the rolling reaction force in the finishing pass is relatively small (hereinafter referred to as the "light rolling pass schedule"). It is possible to make different types of food (called Pasuga Noyur). However, in actual rolling, if a is made extremely large, the rolling reaction force in the finishing pass of rolling becomes large, resulting in problems such as impairing plate thickness accuracy and exceeding the capacity limit of the rolling mill drive motor in the middle pass. There is a practical upper limit to the selectable a. On the other hand, if a is made too small, not only will the number of rolling passes increase and the rolling efficiency will decrease, but the temperature of the material to be rolled will drop, making it difficult to continue rolling, so there is no practical lower limit for a. be. *Also, β also has upper and lower limits to prevent waves from forming on the plate, and the width generally increases as the plate thickness increases.

The steps in FIG. 1 (a) to (6) are based on the means (1) and (2)
corresponds to In creating a rolling pass schedule for a material with variable thickness, in Fig. 1(a), for a flat plate having the minimum thickness Hmin of the material with variable thickness, the upper limit values βa and β of β are
A strong reduction pass schedule using the maximum value aa of a for a is created, and this is called the A schedule, and is the rolling pass schedule corresponding to the minimum thickness of the plate thickness-variable material.

Here, the exit side plate thickness at the n-th pass counting from the finished pass is expressed as Han, and the reaction force is expressed as Fan. ■The lower limit of βb and β for a flat plate with maximum thickness Hwax of variable thickness material
A weak pressure pass schedule is created using the minimum value ab of a with respect to b, and this is called the B schedule.

Here, the exit side plate thickness at the n-th pass counted from the finished pass is expressed as Hbn, and the reaction force is expressed as Fbn. (2) Find the first path where Han≧Hbn in the A%B schedule obtained by the above method. In FIG. 1(b), the B schedule is modified so that Hbn=Han by gradually increasing a of the B schedule to increase the thickness of the outlet side of each pass. ■Final n- of revised B schedule
The schedule for one pass and the A schedule from the rolled material to the plate thickness Han are connected and called the B schedule again.

■For Schedule B, flatness is not guaranteed in connection with Schedule A, so it is determined whether flatness can be maintained. In other words, the minimum thickness schedule and the maximum thickness schedule correspond to the following. If not, increase n by 1 and repeat the steps below.There are various ways to check whether the flatness can be maintained, but a simple method is to change the B schedule to the exit side plate thickness H.
It is possible to back-calculate a1β from the plate thickness and rolling reaction force of the final two passes by terminating up to bn, and check whether the value is within the allowable value for maintaining flatness when Hbn is the product thickness. can. If a more strict guarantee is required, for example, the relationship between plate crown ratio change and flatness (Iron and Steel Institute of Japan M:VF Report No. 36, Theory and Practice of Plate Rolling, P2O) may be used.

In the first EKI (e), the rolling pass schedule is determined as follows for creating a schedule for the intermediate thickness portion of the variable thickness material. Let H(1) be the plate thickness at a position l from the tip of the plate of variable thickness material, and the internal division ratio of the maximum thickness and minimum thickness of the variable thickness material P (1) = (Hmax-
H(1))/(Hwax H5in)...(2
). The target thickness Hi (Li) at position Li in the i pass corresponding to position 1 of this plate thickness change material is calculated by internally dividing the A schedule and B schedule 1-thickness Ps thickness by P: (1-P). The value Hi (L i) = P H Kaede i + (I P) Hbi
... (3), Li is Li from the tip of the plate
It can be determined using the following formula assuming that the volume from the tip of the plate to 11 is equal to the volume of the plate with variable thickness. *Hi(L iH:j(The corresponding reduction amount is ΔHi(Li)=Hi(Li+1)−Hi(L
i) = P (Hai+1- Hai) + (1-P) (Hbi, 1- Hbi) = PΔHai
+ (1-P) ΔHbi ... (5) Δ■ (: Reduction amount 0 As can be seen from equations (3) and (5), both the exit side plate thickness and the reduction amount are the minimum thickness part of the plate thickness change material, It is a value obtained by internally dividing the value corresponding to the maximum thickness part by P:1-P.In such a case, the rolling reaction force in that pass is also approximately the same internally divided value Fi(Li)#PFai+(1-P ) Fbi = (6
) is known to be.

Furthermore, as in this case, when the i-pass outlet thickness and rolling reaction force are both given by the same internal division ratio of rolling schedules A and B with good flatness, the plate with good flatness can be obtained by rolling according to that schedule. You can get

In the above method, in addition to schedule B corresponding to the maximum thickness part of the variable thickness material, any intermediate thickness H of the variable thickness material
Create a C schedule as a rolling pass schedule for a flat plate with - as the plate thickness, and in the H(+) H- part, the A schedule 1-rule and the C schedule are divided, and in the part H(1)>Ha, the C schedule is created. It is also possible to create a rolling pass schedule for the intermediate thickness section by dividing the schedule into C schedule and B schedule. Furthermore, if the number of rolling bus schedules of the flat plate to be created is increased and an internal division with finer divisions is applied, it is expected that the accuracy will be improved; however, without applying the means (2) of the present invention (1) In some cases, only the rolling pass schedule is applied such that the roll gap is changed during every rolling pass as shown in FIG. 2.

Table 1 shows examples in which corrugated plates were rolled by the conventional method and each method shown in the present invention. Case A is a conventional example in which a difference in thickness in the longitudinal direction is provided only in the final pass. .

Case B is a case of manufacturing by the rolling method described in means (2) above. In this case, the final pass to give the plate thickness difference is
Case C is a case in which only the above-mentioned means (1) is applied, and the roll gap is changed during every rolling pass.

Table 2 shows the pass schedule for the target finishing thickness pattern a for each case, where the subscript i is the pass number, Ha and Fa are the exit side plate thickness and reaction force of each pass at the minimum thickness section, Hb and Fb.
represent the outlet side plate thickness and reaction force of each pass at the maximum thickness, respectively.
The units of Ha and Hb are - and Fa.

The unit of Fb is TON. Note that the first pass and the second pass are tenting passes.

The actual rolling results will be explained below according to Table 1.

In case A, there are medium waves on the large bank in all plate thickness patterns.
Severe ear waves developed in the small thickness area, requiring re-correction. Particularly in the case of the target plate thickness pattern b, the waves are not corrected even after re-straightening, and they end up being scraps. On the other hand, in case B and case C, sufficient flatness is obtained at least after re-straightening for any of the target finishing plate thickness patterns. Controlling the thickness difference between all passes reduces the rolling speed, which increases the rolling time, but in case C, the sheet already has sufficient flatness at the end of rolling. There was no need for further correction.

(Effects of the Invention) As explained above, according to the present invention, it is possible to manufacture a variable thickness material having extremely good flatness over the entire length.

[Brief explanation of the drawing]

FIGS. 1(a) to (e) are diagrams showing specific procedure examples of the present invention, and FIG. 2 is a diagram showing an example of a rolling pass schedule in which the roll gap is changed during every rolling pass. , 3rd
Figures (a) to (c) are diagrams showing examples of metal plates whose thickness changes in the longitudinal direction.

Claims (4)

[Claims] (1) In manufacturing a metal plate product whose thickness changes in the longitudinal direction by rolling a material with the same thickness in the longitudinal direction, a flat plate whose thickness is the maximum thickness of the metal plate product in advance is set as the thickness of the flat plate product. For the flat plate whose minimum thickness is the flat plate product thickness among the metal plate products, a rolling pass schedule is created in which rolling is started from the material of the above thickness and finished with the same number of passes, and the rolling of the material of the metal plate product is performed. For each pass, set the target pass thickness of the maximum thickness part in each pass to the target pass thickness of the pass schedule for the maximum thickness flat plate above, and set the target pass thickness of the minimum thickness part to the target pass thickness of the pass schedule for the minimum thickness flat plate above. , according to a rolling pass schedule in which the target pass thickness of the intermediate thickness portion is a value obtained by internally dividing the target pass thickness of the two types of flat plates by the internal division ratio of the intermediate thickness with respect to the maximum target thickness and minimum target thickness in the metal plate product. A rolling method characterized by rolling. (2) As the rolling pass schedule for the minimum thickness flat plate, a schedule is adopted in which the reduction amount per pass is increased to the limit that can maintain the flatness of the minimum thickness flat plate, and as the rolling pass schedule for the maximum thickness flat plate, a schedule is adopted that increases the rolling amount per pass to the limit that can maintain the flatness of the minimum thickness flat plate. A schedule is created in which the rolling amount per pass is reduced to the limit that can maintain flatness, and the goal of the rolling pass schedule for the minimum thickness flat plate is determined between passes in the same order in reverse order from the final pass of the above two types of rolling pass schedules. Find the first pass in which the pass thickness exceeds the target pass thickness of the rolling pass schedule for the maximum thickness flat plate, and set the target pass thickness of the rolling pass schedule for the maximum thickness flat plate in that pass to the rolling pass schedule for the minimum thickness flat plate in the same pass. The rolling pass schedule of the maximum thickness flat plate is modified to match the target pass thickness, and the same rolling pass schedule as the minimum thickness flat plate is adopted as the rolling pass schedule of the maximum thickness flat plate on the first pass side. The rolling method according to scope 1. (3) Check whether the flatness of the flat plate can be maintained according to the rolling pass schedule for the maximum thickness flat plate, and if it is not possible, change the first pass calculated above one by one to the first pass side. 3. The rolling method according to claim 2, wherein the flatness is checked and the rolling pass schedule of the maximum thickness flat plate is corrected until the pass becomes passable. (4) Create a rolling pass schedule for a plurality of flat plates in which the thickness between the maximum thickness and the minimum thickness in the metal plate product is the thickness of the flat plate product, and use the rolling pass schedule for the intermediate thickness part of the metal plate product as the rolling pass schedule for the metal plate product. Claims 1, 2, or 3 are created using an internal division ratio from a rolling pass schedule for two flat plates having a target thickness of the intermediate thickness part of the product and a target thickness sandwiching it. rolling method.