JP6135390B2 - Work roll or backup roll processing method for use in differential thickness steel plate manufacturing equipment - Google Patents

Description

  The present invention relates to a work roll and / or a backup roll processing method used in a manufacturing apparatus for manufacturing a differential thickness steel sheet having a plate thickness difference in the longitudinal direction, and a differential thickness using a work roll or backup roll processed by this processing method. The present invention relates to a steel plate manufacturing apparatus and manufacturing method.

  In recent years, weight reduction has been promoted in order to improve the fuel efficiency of automobiles. One way to reduce the weight is to improve the metal material constituting the body of the automobile. Specifically, in addition to the method of changing the steel material of the automobile body component to a thin and high strength steel material, or the method of changing the material of the component member to an aluminum alloy or magnesium alloy having a lighter specific gravity than steel, For example, there may be mentioned a method of imparting a thickness distribution to the constituent members so as to reduce the thickness of the constituent members to the limit that can ensure the performance.

  Among these, regarding the method of attaching the plate thickness distribution to the constituent members, the steel plate provided with the plate thickness distribution is generally called a differential thickness steel plate. There are various types of differential thickness steel plates depending on the application. For example, a material having a length of about 2000 mm and a width of about 500 mm, a plate thickness of 2 mm from both ends in the longitudinal direction to 300 mm, and a central portion having a plate thickness of 1.6 mm (plate thickness 2 level symmetrical type), or conversely in the longitudinal direction From the both ends to 300 mm, a plate type with a plate thickness of 1.8 mm and a central portion with a plate thickness of 2.0 mm (plate thickness 2 level symmetrical type) can be mentioned. Other examples include those in which the plate thickness is changed in a taper shape in the longitudinal direction, and those having a multi-level thickness or a symmetric or asymmetric type.

  As an apparatus for producing such a differential thickness steel sheet, for example, an apparatus that uses a rolling mill to operate the work roll reduction position (roll gap) during rolling can be considered (for example, Patent Document 1). In particular, in the rolling apparatus described in Patent Document 1, a load cell for detecting a rolling load is provided, and the rolling load detected by the load cell is reduced so as to be a required load calculated based on a required plate thickness. The device is controlled. In addition, since the apparatus using a press other than the apparatus using a rolling mill can be considered as the apparatus for manufacturing the differential thickness steel sheet, in this specification, an apparatus or a method for manufacturing the differential thickness steel sheet using the rolling mill. Is specifically referred to as a manufacturing apparatus or manufacturing method of a differential thickness steel sheet by a rolling method.

  By the way, as a manufacturing apparatus or manufacturing method of a differential thickness steel sheet by a rolling method, the sheet thickness of the material to be rolled on the rolling mill exit side is detected by a sheet thickness detecting device provided on the rolling mill exit side, and based on the detected value. It is possible to control the reduction position. However, in the differential thickness steel plate, the length in the rolling direction of the portion where the plate thickness is constant is generally short. For this reason, since there is a certain distance from the roll bite outlet to the plate thickness detecting device, a dead time occurs, and this device cannot perform appropriate plate thickness control.

  Further, as another manufacturing apparatus or manufacturing method of the differential thickness steel sheet by the rolling method, the thickness and speed of the material to be rolled on the entrance side of the rolling mill and the speed of the material to be rolled on the exit side of the rolling mill are detected, and the mass flow is constant. It is also conceivable to estimate the sheet thickness of the material to be rolled on the exit side of the rolling mill using the law and to control the reduction position based on the estimated value. However, it is difficult to install a device for detecting the speed of the material to be rolled on the exit side of the rolling mill in the immediate vicinity of the roll bite outlet even in the device using the constant mass flow rule, and there is a waste time, Since an estimation error occurs in the thickness of the material to be rolled due to the widening of the width, appropriate thickness control cannot be performed even with this apparatus. In addition, this apparatus requires a plurality of speed detection devices and plate thickness detection devices, which increases the equipment cost.

  In consideration of such a situation, apparatuses using a preset rolling method and an absolute value rolling method have been proposed as a manufacturing apparatus or manufacturing method of a differential thickness steel sheet by a rolling method. In the preset rolling method, the relationship between the rolling position of the rolling mill and the thickness of the material to be rolled that has been rolled by the rolling mill is obtained in advance by experiments or numerical calculations. During rolling, the rolling length, which is the length in the rolling direction of the part already rolled by the rolling mill, of the material being rolled by the rolling mill is calculated based on the rotation speed of the work roll, and in advance The reduction position is controlled so that the plate thickness pattern of the material to be rolled becomes the target plate thickness pattern based on the relationship between the calculated reduction position and the thickness after rolling, and the calculated rolling length.

  In the absolute value rolling method, the relationship between the rolling load and the deformation of the rolling mill (deformation characteristics of the rolling mill) is obtained in advance by experiments, numerical calculations, and the like. During rolling, the rolling length is calculated based on the rotation speed of the work roll, and the rolling load is detected at the roll bite outlet on the basis of the deformation characteristics of the rolling mill determined in advance and the detected rolling load. The thickness of the material to be rolled is estimated. Then, the reduction position is controlled so that the thickness estimated in this way becomes the target thickness based on the calculated rolling length.

  Moreover, as another manufacturing apparatus for manufacturing the differential thickness steel plate, a work roll formed by smoothly changing a radial distance from the rotation center axis to the peripheral surface or a cam-shaped peripheral surface. There is also one using the above (for example, Patent Document 2). By using such a work roll, the roll gap between the work roll formed so as to have a cam-shaped peripheral surface and the other work roll is sequentially changed, thereby reducing the thickness of the material to be rolled. It can be changed sequentially.

JP-A-3-281010 JP-A-55-24733

  By the way, as described above, in the apparatus for producing a differential thickness steel sheet by the rolling method, the thickness of the material to be rolled is basically changed by changing the rolling position of the rolling mill. When such an apparatus is used, it is necessary to increase the control speed of the reduction position in order to increase the production speed (productivity) of the differential thickness steel sheet. In general, since the hydraulic pressure reduction device has high responsiveness, it is essential to install the hydraulic pressure reduction device in order to increase the control speed of the reduction position. However, since the hydraulic reduction device is expensive, the equipment cost increases, and as a result, the manufacturing cost of the differential thickness steel sheet increases. For this reason, there is a demand to manufacture a differential thickness steel plate with a rolling mill having an inexpensive electric reduction device.

  By the way, although the method of manufacturing a difference thickness steel plate using eccentricity of a work roll (a radius changes in the circumferential direction) with a rolling mill having an electric reduction device is effective, the eccentric amount (in the circumferential direction) The target thickness distribution of the differential thickness steel sheet cannot be obtained unless the roll is processed by accurately setting the amount of change in which the radius changes. For this reason, conventionally, rolls were processed while performing trial and error, which required a great deal of time and money. For this reason, there has been a demand for a method of processing a roll by accurately setting such an eccentric amount (the amount of change in which the radius changes in the circumferential direction).

  In addition, when a differential thickness steel plate having a wide plate width and a thin plate thickness is manufactured using the eccentricity of the work roll (the radius changes in the circumferential direction) in the rolling mill having the electric reduction device described above, the plate shape There was a problem that changed. In order to prevent this change in plate shape, it is possible to change the deflection of the roll by, for example, a work roll bender, but since the response of a normal work roll bender is generally slow (several hertz), the shape is kept constant. Therefore, a new problem arises that the rolling speed has to be reduced.

  Therefore, in view of the above problems, an object of the present invention is to process a work roll for accurately setting an eccentricity amount to manufacture a differential thickness steel plate having a desired thickness or for preventing a change in plate shape. It is providing the manufacturing method or manufacturing method of a difference thickness steel plate using the processing method which performs this, and the work roll manufactured by this processing method.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive research, and the radius of at least one of the pair of work rolls is changed in the circumferential direction even if the reduction position is hardly operated. Since the differential thickness steel plate can be manufactured at a relatively high production rate by forming the differential thickness steel plate, and in this case, it is almost unnecessary to operate the reduction position, the reduction device used at this time is It has been found that an electric reduction device with low responsiveness may be used.

  Furthermore, by imparting a crown in the body length direction of the work roll formed so that the radius changes in the circumferential direction, it is possible to suppress changes in the plate shape even in the case of a differential thickness steel plate with a particularly thin plate thickness and a wide plate width. As a result, it was found that a product having excellent flatness can be produced.

This invention was made | formed based on the said knowledge, and the summary is as follows.
(1) Provided with a two-high rolling mill having an electric reduction device and a pair of work rolls formed such that at least one of the radii changes in the circumferential direction, the thickness h _i in n stages in the rolling direction In the processing method for processing the work roll used in the manufacturing apparatus of the differential thickness steel plate in which (i = 1 to n) changes, using the same material as the differential thickness steel plate manufactured in the manufacturing apparatus, In the two-high rolling mill in which the work rolls are changed to a pair of work rolls having a constant radius in the circumferential direction, a pair is formed so as to have a thickness h _n-1 of the differential thickness steel plate manufactured by the manufacturing apparatus. after setting the roll gap between the work rolls, the thickness in the rolling direction of the tailor welded blank h _n, h _1, h _2, · · ·, and the roll gap operation step of operating the roll gap so as to h _n , Roll gap operation worker above H _1, h ₂ thickness of tailor welded blank is in, ..., roll gap S _1, S ₂ when a h _n, ..., and measuring the S _n, the roll gap and the production And a step of processing at least one of the pair of work rolls so that the radius changes in the circumferential direction based on a plate thickness profile of the differential thickness steel sheet manufactured by the apparatus, Work roll processing method.
(2) the roll sheet thickness of tailor welded blank in a gap operation step h _1, h _2, ···, rolling load P _1, P ₂ when a h _n, ···, measuring the P _n And a step of calculating a roll crown of the work roll so that the bending of the work roll during rolling is constant based on the measured rolling load, and the pair of work rolls based on the calculated roll crown The method for processing a work roll according to (1) above, further comprising a step of processing at least one of the work rolls so that the roll crown changes.
( 3 ) In the rolling direction, comprising a four-high rolling mill having an electric reduction device, a pair of work rolls, and a pair of backup rolls formed so that at least one of the radii changes in the circumferential direction. In a processing method for processing a backup roll used in a manufacturing apparatus for a differential thickness steel sheet in which the plate thickness hi (i = 1 to n) changes in n stages, the same material as the differential thickness steel sheet manufactured in the manufacturing apparatus is used. In the four-high rolling mill in which the backup roll is changed to a pair of backups having a constant radius in the circumferential direction using a plate material, the thickness h _n-1 of the differential thickness steel plate manufactured by the manufacturing apparatus is after setting the roll gap between a pair of work rolls so that the plate thickness h _n in the rolling direction of the tailor welded blank, h _1, h _2, to operate the roll gap so ..., a h _n Rolli And-up operation step, the roll thickness of tailor welded blank in a gap operation step h _1, h _2, · · ·, roll gap S _1, S ₂ when a h _n, · · ·, a S _n Based on the measuring step and the thickness gap of the differential thickness steel plate manufactured by the roll gap and the manufacturing apparatus, the radius of at least one backup roll of the pair of backup rolls changes in the circumferential direction. A process for processing a backup roll, characterized in that it includes a step of processing into a roll.
(4) the roll sheet thickness of tailor welded blank in a gap operation step h _1, h _2, ···, rolling load P _1, P ₂ when a h _n, ···, measuring the P _n And a step of calculating a roll crown of a backup roll so that the work roll deflection during rolling is constant from the measured rolling load, and based on the calculated roll crown, among the pair of backup rolls characterized in that it comprises a step of processing at least one of the backup rolls so that the roll crown is changed, the processing method of the backup roll as described in the above (3).

  Provided are a processing method for processing a roll by accurately setting an eccentricity amount, and a manufacturing apparatus for a differential thickness steel plate excellent in flatness using a roll manufactured by this processing method.

FIG. 1 is a diagram schematically showing a production apparatus for a differential thickness steel plate according to a first embodiment of the present invention. FIG. 2 is an enlarged schematic view of a pair of work rolls of a rolling mill in the manufacturing apparatus of the first embodiment. FIG. 3 is a cross-sectional view showing dimensions of a differential thickness steel plate manufactured as an example. FIG. 4 is a diagram schematically showing a production apparatus for a differential thickness steel plate according to a second embodiment of the present invention. FIG. 5 is an enlarged schematic view of a pair of work rolls and a pair of backup rolls of a rolling mill in the manufacturing apparatus of the second embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are assigned to similar components.

  FIG. 1 is a view schematically showing a first embodiment of a production apparatus 1 for a differential thickness steel sheet having a thickness difference in the rolling direction according to the present invention. As shown in FIG. 1, the manufacturing apparatus 1 includes a payoff reel 11 on which a metal strip S as a material to be rolled is unwound and a metal strip S wound on the payoff reel 11 on the entry side of the rolling mill 10. The unwinding pinch roll 12 and the entrance side deflector roll 13 which changes the advancing direction (direction shown by the arrow in FIG. 1) of the metal strip S are provided.

  In addition, the manufacturing apparatus 1 includes a plate thickness sensor (plate thickness detection device) 14 that detects the thickness of the metal strip S rolled by the rolling mill 10 on the exit side of the rolling mill 10, and the traveling direction of the metal strip S. And a take-up reel 16 that winds up the metal strip S.

  In the present embodiment, the rolling mill 10 is a two-stage rolling mill and includes a pair of work rolls 17 and 18. Each work roll 17 and 18 is formed to have a sintered layer on its surface. An electric reduction device 19 that controls a reduction position of the upper work roll 17 (that is, a roll gap between the work rolls 17 and 18) is provided on the upper portion of a roll chock (not shown) of the upper work roll 17. Further, a load cell (not shown) for detecting a rolling load is provided on the upper part of the upper work roll 17. The electric reduction device 19 and the load cell are connected to the control device 20. Therefore, the rolling load detected by the load cell is input to the control device 20, and the electric reduction device 19 is controlled by the control device 20.

  In the manufacturing apparatus 1 configured as described above, the metal strip S that is a material to be rolled is set in the manufacturing apparatus 1 in a state of being wound around the payoff reel 11. A pinch roll 12 is provided on the downstream side of the payoff reel 11 in the traveling direction of the metal strip S. The pinch roll 12 is driven by a driving device (not shown) such as a motor, and unwinds the metal strip S wound around the payoff reel 11. An entrance deflector roll 13 is provided on the downstream side of the pinch roll 12 in the traveling direction of the metal strip S. The entrance side deflector roll 13 is a rotatable roll that is not driven by a driving device or the like. The metal strip S that has passed through the entrance-side deflector roll 13 is inserted between the upper work roll 17 and the lower work roll 18 of the rolling mill 10 and rolled.

  In this embodiment, the rotational speed of the pinch roll 12 is controlled so that a predetermined slack is formed in the metal strip S between the pinch roll 12 and the entrance deflector roll 13 as shown in FIG. . By forming a predetermined slack in the metal strip S in this way, a tension applied to the metal strip S on the inlet side of the rolling mill 10 by the dead weight of the metal strip S (hereinafter referred to as “roller inlet side tension”) is a predetermined tension. Can be kept in. As a method for keeping the rolling mill entry side tension constant, it is generally necessary to separately provide an expensive facility for controlling the tension. In this embodiment, however, the pinch roll 12 and the entry side deflector roll 13 are not provided. The tension on the entry side of the rolling mill is controlled only by controlling the slack of the metal strip S. For this reason, according to this embodiment, the rolling mill entry-side tension can be controlled with inexpensive equipment.

  On the other hand, a plate thickness sensor 14 for detecting the plate thickness of the metal strip S is disposed immediately downstream of the rolling mill 10 in the traveling direction of the metal strip S. The plate thickness sensor 14 is connected to the control device 20. The control device 20 feedback-controls the reduction position of the upper work roll 17 based on the plate thickness detected by the plate thickness sensor 14.

  Accordingly, when the plate thickness detected by the plate thickness sensor 14 is different from a preset plate thickness target value, the reduction position by the electric reduction device 19 is corrected so that these deviations become zero. For example, when the plate thickness detected by the plate thickness sensor 14 is larger than a preset plate thickness target value, the reduction position of the upper work roll 17 is set so that the roll gap between the work rolls 17 and 18 becomes small. Can be lowered. Conversely, when the plate thickness detected by the plate thickness sensor 14 is smaller than a preset plate thickness target value, the rolling position of the upper work roll 17 is increased so that the roll gap between the work rolls 17 and 18 is increased. Is raised.

  An exit deflector roll 15 is provided on the downstream side of the thickness sensor 14 in the traveling direction of the metal strip S. The exit deflector roll 15 is a rotatable roll that is not driven by a driving device or the like. A take-up reel 16 is provided on the downstream side of the outlet deflector roll 15, and the metal strip S is taken up by the take-up reel 16.

  In the present embodiment, a plurality of roller guides (not shown) are provided on the upstream side of the rolling mill 10 in the traveling direction of the metal strip S in order to fix a horizontal position perpendicular to the traveling direction of the metal strip S. Is provided.

  In the present embodiment, a lubricating oil supply device (not shown) for supplying rolling lubricating oil (for example, emulsion lubricating oil) for rolling lubrication to the roll bite inlet of the rolling mill 10 is provided. In addition, a work roll cooling device (not shown) for cooling the work rolls 17 and 18 is provided in the vicinity of the work rolls 17 and 18. In particular, the lubricating oil used in the lubricating oil supply device and the cooling medium used in the work roll cooling device are the same lubricating oil. For this reason, the lubricating oil supply device and the work roll cooling device are supplied with lubricating oil from a common lubricating oil tank and lubricated via a lubricating oil recovery tank (not shown) provided at the lower part of the rolling mill 10. Collected in oil tank.

  Furthermore, in the said embodiment, the rolling of a difference thickness steel plate is continuously performed using the continuous metal strip S. FIG. However, for example, a metal strip S having a predetermined length may be supplied to the rolling mill 10. In this case, instead of the payoff reel 11 and the take-up reel 16, a storage device or the like that stores a predetermined length of the metal strip S in a stacked manner is used.

FIG. 2 is an enlarged schematic view of the pair of work rolls 17 and 18 of the rolling mill 10 in the manufacturing apparatus 1 of the present embodiment. As can be seen from FIG. 2, in the present embodiment, the work rolls 17 and 18 are formed so that the radius changes in the circumferential direction. Specifically, each work roll 17, 18 has two regions, a region having a small radius (region of radius r ₁ ) and a region having a large radius (region of radius r ₂ ).

In particular, in this embodiment, the upper work roll 17 and the lower work roll 18 are formed to have a symmetrical shape, and the work rolls 17 and 18 are rotated synchronously so as to operate symmetrically. It is done. Therefore, when the upper work roll 17 is rolling in the area of the radius r ₁ , the lower work roll 18 is also rolled in the area of the radius r ₁ . Similarly, when the upper work roll 17 is rolling in the area of radius r ₂ , the lower work roll 18 is also rolled in the area of radius r ₂ .

As described above, the work rolls 17 and 18 are formed so that the radii change in the circumferential direction, so that the thickness of the metal strip S rolled by the rolling mill 10 changes. Specifically, the thickness of the metal strip S rolled in the region of the work rolls 17 and 18 with the radius r ₁ is increased, and conversely, the roll is performed in the region of the work rolls 17 and 18 with the radius r _2. The thickness of the broken metal strip S is reduced.

When the metal strip S is rolled using such work rolls 17 and 18, a differential thickness steel plate having a pattern as shown in FIG. 3 can be obtained. The thin central portion of the differential thickness steel plate of FIG. 3 is a portion that has been rolled in the region of the radius r ₂ of the work rolls 17 and 18, and the central thickness of the differential thickness steel plate of FIG. The portion is a portion where rolling has been performed in the region of the radius r ₁ of the work rolls 17 and 18. The differential thickness steel plate shown in FIG. 3 shows a part of the metal strip S manufactured by the manufacturing apparatus 1 of the present embodiment. Actually, the differential thickness steel plate shown in FIG. Will be manufactured.

In the example shown in FIG. 2, one differential thickness steel plate shown in FIG. 3 is manufactured every time the work rolls 17 and 18 rotate once. However, a plurality of the differential thickness steel plates shown in FIG. 3 may be manufactured each time the work rolls 17 and 18 are rotated once. However, in the example shown in FIG. 2, only one region where the radius of the work rolls 17 and 18 is r ₂ is provided for one rotation of the work rolls 17 and 18, but the work rolls 17 and 18 rotate once. In order to produce a plurality of the differential thickness steel plates shown in FIG. 3 each time, it is necessary to provide a plurality of regions where the radius of the work rolls 17 and 18 is r ₂ with respect to one round of the work rolls 17 and 18. It becomes. And in the example shown in FIG.2 and FIG.3, although the perimeter of work rolls 17 and 18 corresponds with the product length of the difference thickness steel plate manufactured, It is necessary to make it an integral multiple (2 times or more) of the manufactured differential thickness steel sheet.

  In the example shown in FIG. 2, the upper work roll 17 and the lower work roll 18 are formed to have a symmetrical shape. However, depending on the differential thickness steel plate to be manufactured, these work rolls 17 and 18 may not have a symmetrical shape.

  For example, only the upper work roll 17 may be formed so that the radius changes in the circumferential direction, and the lower work roll 18 may be formed so that the radius is constant in the circumferential direction. Thereby, the difference thickness steel plate in which the recessed part was formed only in the upper surface can be obtained. In this case, it is preferable that a work roll having a constant radius in the circumferential direction is a carbide roll and a work roll whose radius changes in the circumferential direction is a forged steel roll. The advantage of using a carbide roll is that the rolling load is reduced, the load amplitude during rolling is reduced, which is advantageous for the mechanical life (bearing, etc.), and the load gradient with respect to the rolling reduction is smaller than that of the forged steel roll. The difference in radius that changes in the circumferential direction can be reduced.

  In addition, in this embodiment, when the rolling speed is changed, the rolling load slightly changes. Therefore, it is preferable to correct the reduction position by the electric reduction device 19 based on the plate thickness detected by the plate thickness sensor 14 disposed on the exit side of the rolling mill 10. For example, this correction may be performed only on a portion having a small plate thickness. This correction is for removing a steady-state deviation due to the influence of deformation resistance, friction coefficient, thermal crown, etc. Therefore, the responsiveness may be low, that is, under electric pressure. We can cope enough.

  By the way, the inventor of the present application investigated the relationship between the roll gap S and the plate thickness when using a work roll having a constant circumferential radius, using an apparatus as shown in FIG. Specific experimental conditions are as follows.

  First, as the metal strip S, a material having a tensile strength of 600 MPa called 60 kg high tensile strength was used. The metal strip S was a hot-rolled slit material having a plate thickness of 3.06 mm and a plate width of 400 mm (coil having an oxide scale on the surface called a black skin material).

  Further, as shown in FIG. 3, the difference thickness steel plate as a production target has a total length of 1020 mm and a thickness of 2.90 mm from both ends to 260 mm (+0 to 50 mm) inside, and a central thickness of 500 mm (tolerance 0 to −10 mm). ) Was a concave difference thickness steel plate having a thickness of 1.85 mm.

  In the experiment, tightening was performed in a kiss roll state using a work roll having a constant circumferential radius. At this time, the roll gap was adjusted so that the rolling loads on the work side and the drive side were each 0.1 MN, and the reduced position (roll gap) after adjustment was 0 mm.

  First, the roll gap was opened and closed so that the plate thickness was 3.06 mm and the outlet plate thickness was 1.85 mm, and trial and error were performed and initial setting was performed. At that time, the work roll bender was adjusted and held so that the plate shape was flat.

  Thereafter, the roll gap was released so that the outlet side plate thickness was 2.90 mm, and the roll gap S1 and the rolling load P1 at that time were obtained. Next, the roll gap was tightened so that the exit side plate thickness was 1.85 mm, and the roll gap S2 and the rolling load P2 at that time were obtained.

As a result, when the delivery side plate thickness was 2.90 mm, the rolling load P ₁ was 1.24 MN and the roll gap S ₁ was 2.547 mm. At that time, since the rolling load was reduced and the work roll bender force was kept at the above set value, the work roll bending was small, so that the plate shape was slightly stretched. When the delivery side plate thickness was 1.85 mm, the rolling load P ₂ was 3.42 MN and the roll gap S ₂ was 0.876 mm. At that time, the plate shape was naturally flat.

  The reason why the roll gap and rolling load are obtained by the procedure as described above will be described. Generally, a rolling mill has a phenomenon called hysteresis. That is, the rolling mill has sliding resistance between the backup roll chock and the work roll chock that support the housing and the roll. Therefore, the rolling load is different between the case where the roll gap is tightened at the same rolling position and the case where the roll gap is released because the direction of the sliding resistance is different. Since this hysteresis differs depending on the rolling mill and the material to be rolled, it is difficult to calculate, and it is necessary to obtain it through experiments. In this experiment, when hysteresis was obtained at a plate thickness of 2.90 mm, a hysteresis of about 0.2 MN at the maximum was recognized. The mill constant of this experimental machine is about 3 MN / mm, and it can be seen that an error of about 70 μm occurs in the plate thickness due to the influence of hysteresis. In the present invention, since the influence of this hysteresis can be taken into consideration, it is possible to prevent the occurrence of errors caused by the influence of hysteresis.

  Then, from this experiment, if the rolling position is increased by about 1.671 mm from the rolling position of 0.876 mm, that is, if the roll gap is widened from 0.876 mm to 1.671 mm, the steel sheet thickness after rolling becomes 1. It turns out that it changes from 85 mm to 2.90 mm. Changing the roll gap S can be performed not only by changing the reduction position, but also by changing the radius of the work roll.

Therefore, from this experimental result, when manufacturing the differential thickness steel plate as shown in FIG. 3 using the rolling mill used in the experiment, the region of radius r _{1 in} FIG. 2 (region having a small radius). a circumferential length of about 520mm (260mm × 2), the circumferential length of the region of the radius r ₂ (region a larger radius) together with a 500mm, 0.835mm than the radius r ₁ radius r ₂ (1.671mm / ₂ It can be seen that it is sufficient to use a work roll that is only smaller. Further, a boundary portion between regions having different radii may be processed into a tapered shape to some extent. By actually rolling the differential thickness steel plate using the work roll subjected to such initial processing, and finely adjusting the radius of each region based on the data after rolling, the differential thickness as shown in FIG. Steel sheets can be manufactured.

  Although the differential thickness steel plate having the desired thickness distribution could be manufactured by the above-described method, some problems remain in the plate shape. That is, there is a problem that the plate shape with the outlet side plate thickness of 2.90 mm is slightly stretched. Therefore, in the present invention, a roll crown (concave shape) is imparted to the work roll portion corresponding to this portion. The roll crown is determined so as to coincide with the roll deflection (roll gap) when the plate thickness is 1.85 mm and the shape is flat at the work roll bender setting value. Although there are various methods for obtaining it, for example, it may be calculated using a finite element method or the like. When the roll crown was obtained by this method, it was found that the parabolic pattern was about 50 μm / radius (concave). Therefore, as a result of newly applying such a roll crown to the roll portion corresponding to the exit side plate thickness of 2.9 mm in the plate width direction, a differential thickness steel plate having a desired plate thickness distribution and excellent flatness is manufactured. I was able to.

Therefore, in this embodiment, the work rolls 17 and 18 used for the apparatus for manufacturing a differential thickness steel sheet whose thickness h _i (i = 1 to n) changes in n stages in the rolling direction in the following procedure. It can be said that the radius is changed in the circumferential direction.

First, using the same material as the differential thickness steel plate manufactured in the rolling mill 10, using a pair of work rolls having a constant radius in the circumferential direction as work rolls in the rolling mill 10, the manufacturing apparatus The roll gap between the pair of work rolls is set so that the thickness h _n-1 of the manufactured differential thickness steel sheet is obtained. In the example shown in FIG. 3, since h ₁ = 2.90 mm, h ₂ = 1.85 mm, and h ₃ (h _n ) = 2.90 mm, the roll gap has a plate thickness h ₂ = 1.85. Set to be. Thereafter, the roll gap is changed so that the plate thickness changes in the order of h ₃ , h ₁ , h ₂ , h ₃ (that is, changes in the order of h _n , h ₁ , h ₂ ,..., H _n ). Operated.

And while operating the roll gap as described above, the plate thickness of the differential thickness steel sheet is h ₁ , h ₂ , h ₃ (ie, h ₁ , h ₂ ,..., H _n ). Roll gaps S ₁ , S ₂ , S ₃ (ie, S ₁ , S ₂ ,..., _Sn ) and rolling loads P ₁ , P ₂ , P ₃ (ie, P ₁ , P ₂ ,..., P _n ) is measured by a roll gap detector and a rolling load detector, respectively. Then, based on the roll gap detected in this way, at least one of the pair of work rolls is processed so that the radius changes in the circumferential direction.

  Further, based on the rolling load measured by the rolling load measuring device, the roll crown of the work roll is calculated so that the work roll deflection during rolling is constant. Based on the roll crown thus calculated, at least one of the pair of work rolls is processed so that the roll crown changes.

  When the upper and lower work rolls are processed, processing is performed with ½ of the gap amount, and when only one work roll is processed, processing is performed with 1/1 of the gap amount. When machining the upper and lower work rolls, the machining amount (grinding amount) decreases, and the tolerance of the machining amount due to the effective quenching length increases, but the upper and lower work rolls need to be synchronized. For this reason, a synchronizer that mechanically synchronizes the upper and lower work rolls is required. On the other hand, when processing one-side work roll, the processing amount (grinding amount) increases, and the tolerance of the processing amount due to the effective quenching length decreases, but the above-described synchronization of the upper and lower work rolls is unnecessary.

  Next, a second embodiment of the present invention will be described with reference to FIG. The configuration of the manufacturing apparatus in the second embodiment is basically the same as the configuration of the manufacturing apparatus in the first embodiment. However, the manufacturing apparatus in the first embodiment uses a two-high rolling mill, whereas in the present embodiment, a four-high rolling mill is used.

  The rolling mill 30 according to this embodiment includes a pair of work rolls 31 and 32 and a pair of backup rolls 33 and 34. Each work roll 31, 32 is formed so as to have a sintered layer on its surface. An upper backup roll 33 is disposed above the upper work roll 31, and a lower backup roll 34 is disposed below the lower work roll 32.

  On the upper portion of the upper chock (not shown) of the upper backup roll 33, an electric reduction device 19 that controls the reduction position of the upper work roll 31 (that is, the roll gap between the work rolls 31 and 32) is provided. Further, a roll cell (not shown) for detecting a rolling load is provided on the upper portion of the upper backup roll 33.

FIG. 5 is an enlarged schematic view of the pair of work rolls 31 and 32 and the pair of backup rolls 33 and 34 of the rolling mill 30 in the manufacturing apparatus 1 of the present embodiment. As can be seen from FIG. 5, in the present embodiment, each work roll 31, 32 is formed such that its radius is constant in the circumferential direction. On the other hand, each backup roll 33, 34 is formed such that its radius changes in the circumferential direction. More specifically, the backup rolls 33 and 34, has two areas of a region that a smaller radius (area of radius r _3), a region the radius thereof is large (area of radius r _4).

In particular, in this embodiment, the upper backup roll 33 and the lower backup roll 34 are formed to have a symmetrical shape, and these backup rolls 33 and 34 are rotated synchronously so as to operate symmetrically. It is done. Therefore, when the upper backup roll 33 is rolling in the area of radius r ₃ , the lower backup roll 34 is also rolled in the area of radius r ₃ . Similarly, when the upper backup roll 33 is rolling in the area with the radius r ₄ , the lower backup roll 34 is also rolled in the area with the radius r ₄ .

In this way, the thickness of the metal strip S rolled by the rolling mill 30 changes as the backup rolls 33 and 34 are formed so that the radius changes in the circumferential direction. Specifically, the thickness of the metal strip S that has been rolled in the region of the radius r ₃ of the backup rolls 33 and 34 is increased, and conversely, the rolling is performed in the region of the radius r ₄ of the backup rolls 33 and 34. The thickness of the broken metal strip S is reduced.

When the metal strip S is rolled using such backup rolls 33 and 34, a differential thickness steel plate as shown in FIG. 3 can be obtained. The thin central portion of the differential thickness steel plate in FIG. 3 is a portion that has been rolled in the region of the radius r ₄ of the backup rolls 33 and 34, and the central thickness of the differential thickness steel plate in FIG. The portion is a portion where rolling has been performed in the region of the radius r ₃ of the backup rolls 33 and 34. The differential thickness steel plate shown in FIG. 3 shows a part of the metal strip S manufactured by the manufacturing apparatus 1 of the present embodiment. Actually, the differential thickness steel plate shown in FIG. Will be manufactured.

Moreover, in this embodiment, the backup rolls 33 and 34 used for the apparatus for manufacturing a differential thickness steel plate whose thickness h _i (i = 1 to n) changes in n stages in the rolling direction in the following procedure. It can be said that the radius is changed in the circumferential direction.

First, by using a plate material made of the same material as the differential thickness steel plate manufactured in the rolling mill 30, a pair of backup rolls having a constant radius in the circumferential direction are used as backup rolls in the rolling mill 30 by the manufacturing apparatus 1. The roll gap between the pair of work rolls is set so that the thickness h _n-1 of the manufactured differential thickness steel sheet is obtained. In the example shown in FIG. 3, since h ₁ = 2.90 mm, h ₂ = 1.85 mm, and h ₃ (h _n ) = 2.90 mm, the roll gap has a plate thickness h ₂ = 1.85. Set to be. Thereafter, the roll gap is changed so that the plate thickness changes in the order of h ₃ , h ₁ , h ₂ , h ₃ (that is, changes in the order of h _n , h ₁ , h ₂ ,..., H _n ). Operated.

And while operating the roll gap as described above, the plate thickness of the differential thickness steel sheet is h ₁ , h ₂ , h ₃ (ie, h ₁ , h ₂ ,..., H _n ). Roll gaps S ₁ , S ₂ , S ₃ (ie, S ₁ , S ₂ ,..., _Sn ) and rolling loads P ₁ , P ₂ , P ₃ (ie, P ₁ , P ₂ ,..., P _n ) is measured by a roll gap detector and a rolling load detector, respectively. Then, based on the roll gap detected in this way, at least one of the pair of backup rolls is processed so that the radius changes in the circumferential direction.

  Further, based on the rolling load measured by the rolling load measuring device, the roll crown of the backup roll is calculated so that the work roll deflection during rolling is constant. Based on the roll crown calculated in this way, at least one of the pair of backup rolls is processed so that the roll crown changes.

In the example shown in FIGS. 2 and 3, two differential thickness steel plates shown in FIG. 3 are manufactured every time the backup rolls 33 and 34 rotate once. However, one or more of the differential thickness steel plates shown in FIG. 3 may be manufactured every time the backup rolls 33 and 34 rotate once. However, in the example shown in FIG. 5, two regions where the radius of the backup rolls 33, 34 is r ₄ are provided for one rotation of the backup rolls 33, 34, but the backup rolls 33, 34 rotate once. In order to produce one or more of the differential thickness steel plates shown in FIG. 3 for each time, the region where the radius of the backup rolls 33, 34 is r ₄ with respect to the circumference of the backup rolls 33, 34 is 1 It is necessary to provide one or three or more. And in the example shown in FIG.5 and FIG.3, it is necessary to make the perimeter length of the backup rolls 33 and 34 into the integral multiple of the product length of the difference thickness steel plate manufactured.

  In the example shown in FIG. 5, the upper backup roll 33 and the lower backup roll 34 are formed to have a symmetrical shape. However, depending on the differential thickness steel sheet to be manufactured, these backup rolls 33 and 34 need not be symmetrical.

  For example, only the upper backup roll 33 may be formed so that the radius changes in the circumferential direction, and the lower backup roll 34 may be formed so that the radius is constant in the circumferential direction. Thereby, the difference thickness steel plate in which the recessed part was formed only in the upper surface can be obtained.

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 10 Rolling machine 11 Pay-off reel 12 Pinch roll 13 Input side deflector roll 14 Plate thickness sensor 15 Outlet deflector roll 16 Winding reel 17 Upper work roll 18 Lower work roll 19 Electric reduction device 20 Control device S Metal strip

Claims (4)

Thickness h _i (i = i = i = n steps) in the rolling direction, comprising a two-high rolling mill having an electric reduction device and a pair of work rolls formed so that at least one of them has a radius changing in the circumferential direction. In the processing method for processing the work roll used for the manufacturing apparatus of the differential thickness steel plate in which 1 to n) change,
In the two-high rolling mill in which the work roll is changed to a pair of work rolls having a constant radius in the circumferential direction, using the same material as the differential thickness steel plate manufactured in the manufacturing apparatus, the manufacturing apparatus After setting the roll gap between the pair of work rolls so that the thickness h _n-1 of the difference thickness steel plate manufactured by the following steps is set, the thickness h _n , h ₁ , h ₂ , ..., a roll gap operation step for operating the roll gap so as to be h _n ,
A step of plate thickness of the tailor welded blank to measure h _1, h _2, · · ·, roll gap S _1, S ₂ when a h _n, ···, S _n in the roll gap operational steps,
Processing at least one of the pair of work rolls so that the radius changes in the circumferential direction based on the roll gap and a thickness profile of the differential thickness steel sheet produced by the production apparatus; A method for processing a work roll, comprising: A step of plate thickness of the tailor welded blank to measure h _1, h _2, · · ·, rolling load P _1, P ₂ when a h _n, · · ·, P _n in the roll gap operational steps,
Calculating the roll crown of the work roll so that the work roll deflection during rolling is constant based on the measured rolling load; and
The workpiece according to claim 1, further comprising a step of processing at least one of the pair of work rolls so that the roll crown changes based on the calculated roll crown. Roll processing method. A four-stage rolling mill having an electric reduction device, a pair of work rolls, and a pair of backup rolls formed so that at least one of the radii changes in the circumferential direction has n stages in the rolling direction. In a processing method for processing a backup roll used in a manufacturing apparatus for a differential thickness steel plate in which the plate thickness hi (i = 1 to n) changes,
In the four-high rolling mill in which the backup roll is changed to a pair of backups having a constant radius in the circumferential direction, using the same material as the differential thickness steel plate manufactured in the manufacturing apparatus, the manufacturing apparatus After setting the roll gap between a pair of work rolls so that the thickness of the differential thickness steel plate to be manufactured becomes h _n-1 , the thickness h _n , h ₁ , h ₂ ,. .., a roll gap operation process for operating the roll gap so as to be h _n ,
A step of plate thickness of the tailor welded blank to measure h _1, h _2, · · ·, roll gap S _1, S ₂ when a h _n, ···, S _n in the roll gap operating step,
Based on the roll gap and the thickness profile of the differential thickness steel plate manufactured by the manufacturing apparatus, processing at least one backup roll of the pair of backup rolls so that the radius changes in the circumferential direction; A method for processing a backup roll, comprising: A step of plate thickness of the tailor welded blank to measure h _1, h _2, · · ·, rolling load P _1, P ₂ when a h _n, · · ·, P _n in the roll gap operational steps,
A step of calculating a roll crown of a backup roll such that the work roll deflection during rolling is constant from the measured rolling load;
The method according to claim 3 , further comprising a step of processing at least one backup roll of the pair of backup rolls based on the calculated roll crown so that the roll crown changes. Processing method for backup roll.

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