CA1302743C - Method of controlling strip crown in planetary rolling - Google Patents
Method of controlling strip crown in planetary rollingInfo
- Publication number
- CA1302743C CA1302743C CA000546995A CA546995A CA1302743C CA 1302743 C CA1302743 C CA 1302743C CA 000546995 A CA000546995 A CA 000546995A CA 546995 A CA546995 A CA 546995A CA 1302743 C CA1302743 C CA 1302743C
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- Prior art keywords
- rolls
- planetary
- slab
- crown
- feeding rolls
- Prior art date
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Abstract
Abstract of the Disclosure Disclosed is a method of controlling a strip crown in planetary rolling in a planetary mill line. A slab of a metal is rolled using a shaped feeding roll or rolls before passing between planetary rolls to shape the profile of the slab in the widthwise direction of the slab so that the shaped slab has a flat central portion, opposite ends thicker than the central portion and side portions thinner than the central portion between the central portion and the side ends. At least one of a pair of the feeding rolls adjacent to the planetary rolls has a roll crown including (i) a central region flat or curved for correcting bend of the feeding roll, (ii) a side end having a diameter smaller than that of the central region, (iii) an enlarged side portion spaced from the side end by a distance determined by a roll gap between the central regions of the pair of feeding rolls and having a diameter larger than that of the central region by 0.1 - 1 % and (iv) a tapered side region between the enlarged side portion and the side end. Then the slab is further rolled by planetary rolls. By this way, a planetary-rolled strip having a substantially flat strip crown is produced.
Description
13~Z743 70756-6 Background of the Invention The present invention relates to a method of controlling strip crown in planetary rolling of metallic material on a planetary mill for improving strip crown of planetary-rolled strips by preventing edge-drop and high spot of the strip crown.
In hot rolling of a strip, there has been used a rolling mill such as a tandem mill, a steckel mill, a planetary mill or the like. The hot strip manufactured by such a rolling mill always has a thickness deviation along the width of the strip which is referred to as a strip crown. The strip crown is classified into a center crown with a slightly increased thickness in the central region of the strip and an edge drop with a sharply decreased thickness in the edge region of the strip. In order to improve the strip crown, in the tandem mill, there have been known some methods such as a method using roll benders for work rolls and backup rolls in finishing the roll stands, a method using a six roll mill referred to as a HC mill and a method using tapered rolls. It has been understood from studies about the tandem rolling that the final strip crown is affected by only the last stand of the finishing roll stands rather than by the forward stands. In view of such an understanding, the last two or three stands of the finishing roll stands in the tandem mill have been modified to provide a shape control function and resulted in substantlal effects.
The planetary mill comprises a pair of backup rolls having a large diameter and a plurality of planetary rolls having a small dlameter arranged around each of the backup rolls. A slab is .......... , _ :~
., ;: . .
',; ' :
~ : `
~3~2'~3 rolled by one to three sets of feeding rolls and then rolled by the planetary rolls. The slab is subjected to a small reduction several times by the planetary rolls, resulting in a large total reduction of more than 90% by the planetary mill. Therefore, the planetary mill has the function of the latter half of roughing roll stands and the finishing roll stands of the tandem mill.
The planetary mill is subjected to a very small roll separating force in spite of a large total reduction and the center crown of the planetary-rolled strip is very small owing to the backup rolls of the large diameter and the total crown depends on the edge drop.
The conventional feeding rolls used in the planetary mill line have straight crowns or curved crowns defined by a quadratic curve for correction of elastic deformation of the rolls or convex crown defined by a sine curve.
The characteristic of the crown of the planetary mill is described, for example, in "Journal of the Japanese Society of the Technology of Plasticity" Vol 22, No. 247. 1981-8, P. 839-846 "the qhape and characteristic of planetary-rolled strip". There is described that the strip crown is affected by many factors.
Furthermore, Japanese Patent Application Laid-open Publication No.
51-66263 discloses a planetary mill of crown controllable type comprising double groups of planetary rolls arranged around the backup rolls, the roll crown of which is adjustable.
The aforementioned "Journal of the Japanese Society of Technology Plasticity" does not disclose any improvement of the ":
strip crown. The arrangement of the rolling mill described in .
.
,, 13~t7~
Japanese Patent Application Laid-open Publication No. 51-66263 can not be adapted for the Sendzimer type planetary mill having single group of planetary rolls. Moreover, when the arrangement of the rolling mill is adapted to the existing planetary mill having double groups of planetary rolls, it is necessary to modify on a large scale and such modification is practically difficult.
When rolling the slab by the planetary mill, the thickness of the rolled strip having for example five feet width, sometimes locally increases in a region width 50-150 mm from the edge of the strip. It is called a high spot. This phenomenon occurs when a slab having a flat crown, after leaving the feeding rolls, is fed to the planetary rolls. The cause of such a phenomenon has not been made entirely clear. It is conjectured that the phenomenon is caused by bending of comparatively slender planetary rolls, but the cause is still unclear. In planetary rolling, when the thickness of the center of the rolled strip is increased, the rolled strip shows center buckling. And when the thickness of the rolled strip is locally increased, the rolled strip tends to show quarter buckling.
Such a phenomenon is entirely contrary to the usual rolling wherein a thinner portion is elongated and shows buckling.
When the pIanetary-rolled strip having the local thickness deviation along the width thereof is rerolled, a complex localized elongation of the strip occurs and such a localized elongation could not be sufficiently corrected by the profile control ~,~
technique so that the locally elongated strip is not used as a rerolling~material.
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13~27~3 As aforementioned, the conventional method of rolling on the planetary mill line has a problem such that the edge drop of the strip crown could not be decreased and the local increase of the thickness, i.e. high spot, could not be prevented.
Summary of the Invention The object of the present invention is to decrease the edge drop and to prevent the local increase of the thickness of planetary- rolled strip.
For the above object, the present invention provides a method of controlling the strip crown in planetary rolling on a planetary mill line comprising feeding rolls and planetary rolls. A metal slab is rolled with the feeding rolls to shape the profile of the slab in the direction of the width of the slab. At least one of a pair of feeding rolls adjacent to the planetary rolls has a roll crown including:
a central region flat or slightly curved for correcting a bend of the feeding rolls;
at least one reduced side end having a diameter smaller than that of the central region;
at least one enlarged side portion, spaced from the said reduced side end by a distance determined by a roll gap between the central regions of the pair of feeding rolls and having a diameter 0.1 - 1 % larger than that of the central region; and a tapered side region between the enlarged side portion and the reduced side end.
After being rolled by the feeding rolls in this way, the slab has a profile in the direction of width, a flat or slightly curved "~
~ : ` ~
, : . . `: ` `' ;. . , - . , 13rJ27~3 central portion, opposite side ends thicker than the central portion and side portions thinner than the central portion between the central portion and the opposite side ends. Then the slab is further rolled by the planetary rolls, thereby providing a planetary-rolled strip having a substantially flat strip crown and a uniform thickness over the width of the strip.
Brief Description of the Drawinas Further objects and advantages of the present invention will become apparent as the following description of the illustrated embodiments proceeds with reference to the drawings in which:
Fig. 1 is a schematic sectional view of an embodiment of a planetary mill line;
Figs. 2 to 5 are schematic views of various embodiments of feeding rolls used in the present invention;
Figs. 6 and 7 are schematic views of conventional feeding rolls;
Figs. 8a and 8b show various slab profiles formed by feeding rolls according to the conventional method;
Figs. 8c to 8f show various slab profiles formed by feeding rolls according to the present invention; and Fig. 9 is a diagram showing the thickness deviations in the direction of width of strips after the slabs shown in Fig. 8 are rolled by planetary rolls.
Detailed Explanation of the Preferred Embodiments As shown in Fig. 1, a planetary mill normally includes edge ~ rolls 7, feeding rolls, planetary rolls 6 and planishing rolls 8 :
~ , -5-. ..:
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` 13~2743 and a planetary mill rolled strip 9 is produced.
The inventors made tests and studied the behavior of rolling in planetary mill and found that the strip crown of a planetary rolled strip is largely depended on the three dimensional deformations of the slab and is substantially determined by a combination of the distribution of spreading in the direction of width of the slab and the distribution of elongation in the longitudinal direction of the slab. It was also found from the result of the test that in rolling on the conventional planetary mill line according to the prior art, the edge drop-in problem occurs at a portion in the edge region where the volume of the slab material is insufficient and also the problem of local thickness increase occurs at a portion where the volume of the slab material is excessive.
In view of the above recognition, the inventors made a rolling test on the planetary mill line by using feeding rolls 2 as shown in Fig.2. The feeding rolls 2 have a roll crown such that the central region 3 is flat or is slightly curved (i.e.
convexed) for correcting a bend of the feeding roll and has an enlarged side portion 4 spaced form the side end of the effective rolling width of the feeding roll by a distance determined by a roll gap between the central regions 3,3 of a pair of the feeding rolls 2,2. The diameter of the enlarged side portion 4 is 0.1 -1~ larger than the diameter of the central region of the feeding rolls. Furthermore, the side region 5 between the side enlarged portion 4 and the side end is tapered by a taper angle from the enlarged portion 4 towards the side end. From the result of the : ' ~ . .
. ~ ` . " ' :. ~ ' . , . , :
13~27~3 test using the aforementioned feeding rolls, it was found that the strip crown can be made flat by planetary rolling after the feeding rolls. The diameter of the side enlarged portion 4 and the taper angle of the tapered side region 5 are critical in order to obtain a satisfactory flatness of the strip crown. Since the rolling condition is usually standardized, it is easy to select a correct diameter of the enlarged side portion 4 and the taper angle of the tapered side region 5. For example, when a slab having a width of 1500 mm and a thickness of 83 mm is planetary rolled, it is most preferable that the feeding roll is formed with the enlarged side portion 4 at a position spaced from the side end of the effective rolling width by a distance of 100 mm and is tapered from the enlarged side portion 4 towards the side end.
When the thickness of the slab to be planetary rolled is 55 mm, it is most preferable that the diameter of the feeding roll is decreased from a position spaced from the side end of the effective rolling width by a distance of 80 mm. Fig. 3 shows another embodiment of a pair of the feeding rolls 2 only one of which has the enlarged side portion 4 at the position spaced from the side end and the tapered side region 5 and the other feeding roll 2 has not the enlarged side portion, but this embodiment can ~ provide a similar result. Fig. 4 also shows another embodiment of ;~ a pair of the feeding rolls 2 having the enlarged side portion 4 and the tapered side region 5 at only one side thereof, but this embodiment can also provide a similar result.
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, 13~Z743 70756-6 Example Slabs of stainless steel SUS 304, which is 18-8 type stainless steel, are hot rolled on the planetary mill line according to the method of the present invention.
Fig. 8 shows the crown profile of slabs having a width of 1050 mm after being shaped by the feeding rolls according to the method of the present invention and the conventional rolling method. Figs. 8a and 8b show the slab profiles after being shaped by the feeding rolls according to the conventional method. Fig.
8a shows the crown profile of the slab rolled by the feeding rolls having the straight crown as shown in Fig. 6. Fig. 8b shows the crown profile of the slab rolled by the feeding rolls having the curved crown defined by the quadratic curve or convex crown defined by a sine curve as shown in Fig. 7 and the slab has thickness of 83 mm at the width center and thickness of 85 mm at the side end portions of the effective rolling width.
Figs. 8c, 8d, 8e, 8f show the slab profiles achieved according to the method of the present invention. Fig. 8c shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 2 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portion formed by the enlarged side portions of the upper and the lower feeding rolls and a thickness of 85 mm at the side ends of the effective rolling width. The position of the thin portion in the width direction of the thicker slab is nearer to the width center than the thinner slab. Fig. 8d shows the crown profile of the slab rolled by the feeding rolls having the roll .
. ' : - ~ ' . . . . .
.
13~J2743 crown profile shown in Fig. 3 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portions and a thickness of 85 mm at the side ends of the effective rolling width. Fig. 8e shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 5, one of which feeding rolls has the roll crown the same as that of Fig. 2 and the other has the straight crown and the slab has thickness of 83 mm at the width center, a thickness of 78 mm at the thin positions and a thickness of 85 mm at the side ends of the effective rolling width. Fig. 8f shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 4 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portions and a thickness of 85 mm at the side ends of the effective rolling width of the tapered side region.
Fig. 9 shows relations between distance from the center of strip and the thickness deviation of the strip crown of planetary-rolled strips of the slabs shown in Figs. 8a, 8bl 8c, 8d 8e, and 8f. It is seen from Fig. 9 that the planetary-rolled strips according to the conventional method using the slabs having the straight crown and the sine curved crown shown in Figs. 8a, and 8b have large edge drops and a locally increased thickness as shown in Figs. 9a, and 9b. On the contrary, the planetary-rolled :~
strips according to the present invention using the feeding rolled slabs having crown profile shown in Figs. 8c, 8d, 8e, and 8f have a~small edge drop and a flat crown shape without increased thickness as shown in Fig. 9c, 9d, 9e and 9f shown in Figs. 9a, , 13~27~
' 70756-6 and 9b.
The present invention can also be applied to not only a Sendzimir type planetary mill, but also to a Krupp-Platzer type planetary mill having double groups of planetary rolls.
The present invention can also be applied to Roll Cast type planetary mill, double three high mills, pendulum mills, DSW mills and others of same rolling mechanism as that of the planetary mill.
According to the present invention, it is possible to obtain a planetary-rolled strip having a flat profile with a limited edge drop and local thickness variation and to provide high grade strips usable for cold rolling materials as well as hot rolled products. The present invention is also carried out by preparing the feeding rolls having the desired crown profile shaped by machining with low investment.
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In hot rolling of a strip, there has been used a rolling mill such as a tandem mill, a steckel mill, a planetary mill or the like. The hot strip manufactured by such a rolling mill always has a thickness deviation along the width of the strip which is referred to as a strip crown. The strip crown is classified into a center crown with a slightly increased thickness in the central region of the strip and an edge drop with a sharply decreased thickness in the edge region of the strip. In order to improve the strip crown, in the tandem mill, there have been known some methods such as a method using roll benders for work rolls and backup rolls in finishing the roll stands, a method using a six roll mill referred to as a HC mill and a method using tapered rolls. It has been understood from studies about the tandem rolling that the final strip crown is affected by only the last stand of the finishing roll stands rather than by the forward stands. In view of such an understanding, the last two or three stands of the finishing roll stands in the tandem mill have been modified to provide a shape control function and resulted in substantlal effects.
The planetary mill comprises a pair of backup rolls having a large diameter and a plurality of planetary rolls having a small dlameter arranged around each of the backup rolls. A slab is .......... , _ :~
., ;: . .
',; ' :
~ : `
~3~2'~3 rolled by one to three sets of feeding rolls and then rolled by the planetary rolls. The slab is subjected to a small reduction several times by the planetary rolls, resulting in a large total reduction of more than 90% by the planetary mill. Therefore, the planetary mill has the function of the latter half of roughing roll stands and the finishing roll stands of the tandem mill.
The planetary mill is subjected to a very small roll separating force in spite of a large total reduction and the center crown of the planetary-rolled strip is very small owing to the backup rolls of the large diameter and the total crown depends on the edge drop.
The conventional feeding rolls used in the planetary mill line have straight crowns or curved crowns defined by a quadratic curve for correction of elastic deformation of the rolls or convex crown defined by a sine curve.
The characteristic of the crown of the planetary mill is described, for example, in "Journal of the Japanese Society of the Technology of Plasticity" Vol 22, No. 247. 1981-8, P. 839-846 "the qhape and characteristic of planetary-rolled strip". There is described that the strip crown is affected by many factors.
Furthermore, Japanese Patent Application Laid-open Publication No.
51-66263 discloses a planetary mill of crown controllable type comprising double groups of planetary rolls arranged around the backup rolls, the roll crown of which is adjustable.
The aforementioned "Journal of the Japanese Society of Technology Plasticity" does not disclose any improvement of the ":
strip crown. The arrangement of the rolling mill described in .
.
,, 13~t7~
Japanese Patent Application Laid-open Publication No. 51-66263 can not be adapted for the Sendzimer type planetary mill having single group of planetary rolls. Moreover, when the arrangement of the rolling mill is adapted to the existing planetary mill having double groups of planetary rolls, it is necessary to modify on a large scale and such modification is practically difficult.
When rolling the slab by the planetary mill, the thickness of the rolled strip having for example five feet width, sometimes locally increases in a region width 50-150 mm from the edge of the strip. It is called a high spot. This phenomenon occurs when a slab having a flat crown, after leaving the feeding rolls, is fed to the planetary rolls. The cause of such a phenomenon has not been made entirely clear. It is conjectured that the phenomenon is caused by bending of comparatively slender planetary rolls, but the cause is still unclear. In planetary rolling, when the thickness of the center of the rolled strip is increased, the rolled strip shows center buckling. And when the thickness of the rolled strip is locally increased, the rolled strip tends to show quarter buckling.
Such a phenomenon is entirely contrary to the usual rolling wherein a thinner portion is elongated and shows buckling.
When the pIanetary-rolled strip having the local thickness deviation along the width thereof is rerolled, a complex localized elongation of the strip occurs and such a localized elongation could not be sufficiently corrected by the profile control ~,~
technique so that the locally elongated strip is not used as a rerolling~material.
- ~ '' ,, ~
.
. .
: , . .
:.; . . . .
13~27~3 As aforementioned, the conventional method of rolling on the planetary mill line has a problem such that the edge drop of the strip crown could not be decreased and the local increase of the thickness, i.e. high spot, could not be prevented.
Summary of the Invention The object of the present invention is to decrease the edge drop and to prevent the local increase of the thickness of planetary- rolled strip.
For the above object, the present invention provides a method of controlling the strip crown in planetary rolling on a planetary mill line comprising feeding rolls and planetary rolls. A metal slab is rolled with the feeding rolls to shape the profile of the slab in the direction of the width of the slab. At least one of a pair of feeding rolls adjacent to the planetary rolls has a roll crown including:
a central region flat or slightly curved for correcting a bend of the feeding rolls;
at least one reduced side end having a diameter smaller than that of the central region;
at least one enlarged side portion, spaced from the said reduced side end by a distance determined by a roll gap between the central regions of the pair of feeding rolls and having a diameter 0.1 - 1 % larger than that of the central region; and a tapered side region between the enlarged side portion and the reduced side end.
After being rolled by the feeding rolls in this way, the slab has a profile in the direction of width, a flat or slightly curved "~
~ : ` ~
, : . . `: ` `' ;. . , - . , 13rJ27~3 central portion, opposite side ends thicker than the central portion and side portions thinner than the central portion between the central portion and the opposite side ends. Then the slab is further rolled by the planetary rolls, thereby providing a planetary-rolled strip having a substantially flat strip crown and a uniform thickness over the width of the strip.
Brief Description of the Drawinas Further objects and advantages of the present invention will become apparent as the following description of the illustrated embodiments proceeds with reference to the drawings in which:
Fig. 1 is a schematic sectional view of an embodiment of a planetary mill line;
Figs. 2 to 5 are schematic views of various embodiments of feeding rolls used in the present invention;
Figs. 6 and 7 are schematic views of conventional feeding rolls;
Figs. 8a and 8b show various slab profiles formed by feeding rolls according to the conventional method;
Figs. 8c to 8f show various slab profiles formed by feeding rolls according to the present invention; and Fig. 9 is a diagram showing the thickness deviations in the direction of width of strips after the slabs shown in Fig. 8 are rolled by planetary rolls.
Detailed Explanation of the Preferred Embodiments As shown in Fig. 1, a planetary mill normally includes edge ~ rolls 7, feeding rolls, planetary rolls 6 and planishing rolls 8 :
~ , -5-. ..:
:`- :
' `
` 13~2743 and a planetary mill rolled strip 9 is produced.
The inventors made tests and studied the behavior of rolling in planetary mill and found that the strip crown of a planetary rolled strip is largely depended on the three dimensional deformations of the slab and is substantially determined by a combination of the distribution of spreading in the direction of width of the slab and the distribution of elongation in the longitudinal direction of the slab. It was also found from the result of the test that in rolling on the conventional planetary mill line according to the prior art, the edge drop-in problem occurs at a portion in the edge region where the volume of the slab material is insufficient and also the problem of local thickness increase occurs at a portion where the volume of the slab material is excessive.
In view of the above recognition, the inventors made a rolling test on the planetary mill line by using feeding rolls 2 as shown in Fig.2. The feeding rolls 2 have a roll crown such that the central region 3 is flat or is slightly curved (i.e.
convexed) for correcting a bend of the feeding roll and has an enlarged side portion 4 spaced form the side end of the effective rolling width of the feeding roll by a distance determined by a roll gap between the central regions 3,3 of a pair of the feeding rolls 2,2. The diameter of the enlarged side portion 4 is 0.1 -1~ larger than the diameter of the central region of the feeding rolls. Furthermore, the side region 5 between the side enlarged portion 4 and the side end is tapered by a taper angle from the enlarged portion 4 towards the side end. From the result of the : ' ~ . .
. ~ ` . " ' :. ~ ' . , . , :
13~27~3 test using the aforementioned feeding rolls, it was found that the strip crown can be made flat by planetary rolling after the feeding rolls. The diameter of the side enlarged portion 4 and the taper angle of the tapered side region 5 are critical in order to obtain a satisfactory flatness of the strip crown. Since the rolling condition is usually standardized, it is easy to select a correct diameter of the enlarged side portion 4 and the taper angle of the tapered side region 5. For example, when a slab having a width of 1500 mm and a thickness of 83 mm is planetary rolled, it is most preferable that the feeding roll is formed with the enlarged side portion 4 at a position spaced from the side end of the effective rolling width by a distance of 100 mm and is tapered from the enlarged side portion 4 towards the side end.
When the thickness of the slab to be planetary rolled is 55 mm, it is most preferable that the diameter of the feeding roll is decreased from a position spaced from the side end of the effective rolling width by a distance of 80 mm. Fig. 3 shows another embodiment of a pair of the feeding rolls 2 only one of which has the enlarged side portion 4 at the position spaced from the side end and the tapered side region 5 and the other feeding roll 2 has not the enlarged side portion, but this embodiment can ~ provide a similar result. Fig. 4 also shows another embodiment of ;~ a pair of the feeding rolls 2 having the enlarged side portion 4 and the tapered side region 5 at only one side thereof, but this embodiment can also provide a similar result.
~; :::~
~ 7-, _ ~ ,.. .
, 13~Z743 70756-6 Example Slabs of stainless steel SUS 304, which is 18-8 type stainless steel, are hot rolled on the planetary mill line according to the method of the present invention.
Fig. 8 shows the crown profile of slabs having a width of 1050 mm after being shaped by the feeding rolls according to the method of the present invention and the conventional rolling method. Figs. 8a and 8b show the slab profiles after being shaped by the feeding rolls according to the conventional method. Fig.
8a shows the crown profile of the slab rolled by the feeding rolls having the straight crown as shown in Fig. 6. Fig. 8b shows the crown profile of the slab rolled by the feeding rolls having the curved crown defined by the quadratic curve or convex crown defined by a sine curve as shown in Fig. 7 and the slab has thickness of 83 mm at the width center and thickness of 85 mm at the side end portions of the effective rolling width.
Figs. 8c, 8d, 8e, 8f show the slab profiles achieved according to the method of the present invention. Fig. 8c shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 2 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portion formed by the enlarged side portions of the upper and the lower feeding rolls and a thickness of 85 mm at the side ends of the effective rolling width. The position of the thin portion in the width direction of the thicker slab is nearer to the width center than the thinner slab. Fig. 8d shows the crown profile of the slab rolled by the feeding rolls having the roll .
. ' : - ~ ' . . . . .
.
13~J2743 crown profile shown in Fig. 3 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portions and a thickness of 85 mm at the side ends of the effective rolling width. Fig. 8e shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 5, one of which feeding rolls has the roll crown the same as that of Fig. 2 and the other has the straight crown and the slab has thickness of 83 mm at the width center, a thickness of 78 mm at the thin positions and a thickness of 85 mm at the side ends of the effective rolling width. Fig. 8f shows the crown profile of the slab rolled by the feeding rolls having the roll crown profile shown in Fig. 4 and the slab has a thickness of 83 mm at the width center, a thickness of 78 mm at the thin portions and a thickness of 85 mm at the side ends of the effective rolling width of the tapered side region.
Fig. 9 shows relations between distance from the center of strip and the thickness deviation of the strip crown of planetary-rolled strips of the slabs shown in Figs. 8a, 8bl 8c, 8d 8e, and 8f. It is seen from Fig. 9 that the planetary-rolled strips according to the conventional method using the slabs having the straight crown and the sine curved crown shown in Figs. 8a, and 8b have large edge drops and a locally increased thickness as shown in Figs. 9a, and 9b. On the contrary, the planetary-rolled :~
strips according to the present invention using the feeding rolled slabs having crown profile shown in Figs. 8c, 8d, 8e, and 8f have a~small edge drop and a flat crown shape without increased thickness as shown in Fig. 9c, 9d, 9e and 9f shown in Figs. 9a, , 13~27~
' 70756-6 and 9b.
The present invention can also be applied to not only a Sendzimir type planetary mill, but also to a Krupp-Platzer type planetary mill having double groups of planetary rolls.
The present invention can also be applied to Roll Cast type planetary mill, double three high mills, pendulum mills, DSW mills and others of same rolling mechanism as that of the planetary mill.
According to the present invention, it is possible to obtain a planetary-rolled strip having a flat profile with a limited edge drop and local thickness variation and to provide high grade strips usable for cold rolling materials as well as hot rolled products. The present invention is also carried out by preparing the feeding rolls having the desired crown profile shaped by machining with low investment.
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Claims (11)
1. A method of controlling strip crown in a planetary mill line including feeding rolls and planetary rolls, comprising the steps of:
rolling a slab with feeding rolls to shape a slab profile in the direction of the width of the slab so that the slab profile has a flat or slightly curved central portion, opposite side ends thicker than the central portion and side portions thinner than the central portion between the central portion and the opposite side ends, wherein at least one of a pair of the feeding rolls adjacent to the planetary rolls has a roll crown including (i) a flat or curved central region, (ii) at least one reduced side end having a diameter smaller than that of the central region, (iii) at least one enlarged side portion spaced from the reduced side end by a distance determined by a roll gap between the central regions of the pair of feeding rolls and having a diameter 0.1 - 1 % larger than that of the central region and (iv) a tapered side region between the enlarged side portion and the reduced end; and subsequently rolling the slab having the shaped slab profile by means of planetary rolls, thereby providing a planetary rolled strip having a substantially flat strip crown having a uniform thickness over the width of the strip.
rolling a slab with feeding rolls to shape a slab profile in the direction of the width of the slab so that the slab profile has a flat or slightly curved central portion, opposite side ends thicker than the central portion and side portions thinner than the central portion between the central portion and the opposite side ends, wherein at least one of a pair of the feeding rolls adjacent to the planetary rolls has a roll crown including (i) a flat or curved central region, (ii) at least one reduced side end having a diameter smaller than that of the central region, (iii) at least one enlarged side portion spaced from the reduced side end by a distance determined by a roll gap between the central regions of the pair of feeding rolls and having a diameter 0.1 - 1 % larger than that of the central region and (iv) a tapered side region between the enlarged side portion and the reduced end; and subsequently rolling the slab having the shaped slab profile by means of planetary rolls, thereby providing a planetary rolled strip having a substantially flat strip crown having a uniform thickness over the width of the strip.
2. A method as claimed in claim 1, wherein both of the pair of feeding rolls have the said roll crown.
3. A method as claimed in claim 1, wherein one of the pair of feeding rolls has the said roll crown and the other of the pair of feeding rolls has a curved crown with tapered end portions.
4. A method as claimed in claim 1, wherein each of the feeding rolls has the enlarged side portion at only one side region.
5. A method as claimed in claim 1, wherein one of the pair of the feeding rolls has the said roll crown and the other of the pair of feeding rolls has a straight crown.
6. A method as claimed in claim 2, wherein each of the feeding rolls has the said reduced side end (i), the said enlarged side portion (ii) and the said tapered side region (iii) at opposite sides of the central region (i).
7. A method as claimed in claim 1, wherein each of the feeding rolls has the said reduced side end (i), the said enlarged side portion (ii) and the said tapered side region (iii) at only one side of the central region (i) and has a straight end at the other side.
8. A method as claimed in any one of claim 3, wherein the said one of the pair of feeding rolls having the said roll crown has the said reduced side end (i), the said enlarged side portion (ii) and the said tapered side region (iii) at opposite sides of the central region (i).
9. A method as claimed in any one of claim 5, wherein the said one of the pair of feeding rolls having the said roll crown has the said reduced side end (i), the said enlarged side portion (ii) and the said tapered side region (iii) at opposite sides of the central region (i).
10. A method as claimed in any one of claims 1 to 9, wherein the planetary mill line also includes edge rolls and planishing rolls.
11. A method as claimed in any one of claims 1 to 9, wherein the slab is of stainless steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000546995A CA1302743C (en) | 1987-09-16 | 1987-09-16 | Method of controlling strip crown in planetary rolling |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000546995A CA1302743C (en) | 1987-09-16 | 1987-09-16 | Method of controlling strip crown in planetary rolling |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1302743C true CA1302743C (en) | 1992-06-09 |
Family
ID=4136454
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000546995A Expired - Lifetime CA1302743C (en) | 1987-09-16 | 1987-09-16 | Method of controlling strip crown in planetary rolling |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1302743C (en) |
-
1987
- 1987-09-16 CA CA000546995A patent/CA1302743C/en not_active Expired - Lifetime
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| Date | Code | Title | Description |
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| MKLA | Lapsed |