Thickness control apparatus for rolling mill

Claim 2

A thickness control apparatus for a multi-stand rolling mill in which the thickness of a moving web is changed from a first value to a second value at a certain specific point on the moving web, comprising detecting means for detecting a thickness changing point at each roll stand, gap calculator means for calculating the roll gap changing values for the respective stands according to a coefficient affecting a final output thickness due to the roll gap change in each stand and also a coefficient affecting the tension in each stand due to said roll gap change, the coefficient affecting the final output thickness and the coefficient affecting the tension in each stand being provided by independently changing the roll gaps in the individual stands, and thickness control means for changing the roll gap at each roll stand according to the roll gap changing value provided from said gap calculator means.

Claim 3

A thickness control apparatus as defined in claim 1, wherein said detecting means includes speed detecting means at each roll stand and first means at the first roll stand responsive to an input signal indicating the length of web to be rolled at a standard thickness and the output of said speed detecting means at the first roll stand for generating an output for effecting actuation of said thickness control means at the first roll stand by said gap calculator means.

Claim 4

A thickness control apparatus as defined in claim 2, wherein said detecting means includes second means at each roll stand subsequent to said first roll stand responsive to the output of the detecting means at the previous roll stand and the speed detecting means of the respective roll stand for effecting actuation of said thickness control means of the respective roll stand by said gap calculator means when said specific point on the moving web reaches that roll stand.

Claim 5

A thickness control apparatus for a multi-stand rolling mill in which the thickness of a moving web is changed from a first value to a second value at a specific point on the moving web, comprising: detecting means for detecting the thickness changing point at each roll stand, thickness control means for controlling the roll gap at each roll stand in response to respective gap control signals, roll down control means for providing standard gap control signals for the respective roll stands, gap calculator means responsive to an input gap changing value signal for generating changing value gap control signals including memory means for storing predetermined thickness and tension coefficient values for calculating said changing value gap control signals in accordance with said input gap changing value signal, the thickness and tension coefficient values being provided by changing the roll gap for the respective roll stands independently, summation means for summing the respective standard gap control signals and changing value gap control signals to produce said gap control signals applied to said thickness control means, and gate means associated with each roll stand and responsive to a respective output from said detecting means indicating presence of said changing point at the respective roll stand for applying the changing value gap control signal of the respective roll stand to said summation means.

Claim 6

A thickness control apparatus for a multi-stand rolling mill in which the thickness of a moving web is changed from a first value to a second value at a specific point on the moving web, comprising: detecting means for detecting the thickness changing point at each roll stand, thickness control means for controlling the roll gap at each roll stand in response to respective gap control signals, roll down control means for providing standard gap control signals for the respective roll stands, gap calculator means responsive to an input gap changing value signal for generating changing value gap control signals including memory means for storing predetermined thickness and tension coefficient values for calculating said changing value gap control signals in accordance with said input gap changing value signal, the thickness and tension coefficient values being provided by changing the roll gap for the respective roll stands independently, summation means for summing the respective standard gap control signals and changing value gap control signals to produce said gap control signals applied to said thickness control means, and gate means associated with each roll stand and responsive to a respective output from said detecting means indicating presence of said changing point at the respective roll stand for applying the changing value gap control signal of the respective roll stand to said summation means.

Claim 7

A thickness control apparatus as defined in claim 4, wherein said detecting means includes speed detecting means at each roll stand and first means at the first roll stand responsive to an input signal indicating the length of web to be rolled at a standard thickness and the output oF said speed detecting means at the first roll stand for generating an output for effecting actuation of said thickness control means at the first roll stand by said gap calculator means.

Claim 8

A thickness control apparatus as defined in claim 5, wherein said detecting means includes second means at each roll stand subsequent to said first roll stand responsive to the output of the detecting means at the previous roll stand and the speed detecting means of the respective roll stand for effecting actuation of said thickness control means of the respective roll stand by said gap calculator means when said specific point on the moving web reaches that roll stand.

Claim 9

A thickness control apparatus as defined in claim 6, including thickness detector means located at the output of the last roll stand for detecting the thickness of said web, said gap calculator means further including coefficient correction means responsive to the output of said thickness detector means, said changing value gap control signals, and said input gap changing value for correcting the predetermined thickness and tension values stored in said memory means.

Claim 10

A thickness control apparatus as defined in claim 7, wherein said gap calculator means further includes tension changing value memory means for storing tension changing values adapted to the changing value of the final output thickness of said moving web.

Claim 11

A thickness control apparatus as defined in claim 4, including thickness detector means located at the output of the last roll stand for detecting the thickness of said web, said gap calculator means further including coefficient correction means responsive to the output of said thickness detector means, said changing value gap control signals, and said input gap changing value for correcting the predetermined thickness and tension values stored in said memory means.

Claim 12

A thickness control apparatus for a multi-stand rolling mill in which the thickness of a moving web is changed from a first value to a second value at a certain specific point on the moving web comprising roll speed detectors disposed at each of the individual stands, detector means for detecting the thickness changing point at each roll stand according to the roll speed detected by said roll speed detector, gap calculator means in which the first stand roll gap changing value is calculated by the coefficient affecting the final output thickness thereof due to the roll gap change in the first stand and the roll gap changing values in the stands subsequent to the first stand are calculated by using the roll gap changing value in the first stand and the coefficient affecting the uncoiler side tension in the stands subsequent to the first stand, and roll gap controller means for controlling the roll gaps of the stand in response to control from said thickness changing point detecting means according to the roll gap changing values provided from said gap calculator means.

Claim 13

A thickness control apparatus for a multi-stand rolling mill in which the thickness of a moving web is changed from a first value to a second value at a certain specific point on the moving web comprising roll speed detectors disposed at each of the individual stands, detector means for detecting the thickness changing point at each roll stand according to the roll speed detected by said roll speed detector, gap calculator means in which the first stand roll gap changing value is calculated by the coefficient affecting the final output thickness thereof due to the roll gap change in the first stand and the roll gap changing values in the stands subsequent to the first stand are calculated by using the roll gap changing value in the first stand and the coefficient affecting the uncoiler side tension in the stands subsequent to the first stand, and roll gap controller means for controlling the roll gaps of the stand in response to control from said thickness changing point detecting means according to the roll gap changing values provided from said gap calculator means.

Claim 14

A thickness control apparatus as defined in claim 10, including thickness detector means located at the output of the last roll stand for detecting the thickness of said web, said gap calculator means including memory means for storing predetermined thickness and tension coefficient values for each roll stand and coefficient correction means responsive to the output of said thickness detector means and the roll gap changing values for correcting said predetermined thickness and tension values stored in said memory means.

Claim 15

A thickness control apparatus as defined in claim 11, wherein said gap calculator means further includes tension changing value memory means for storing tension changing values adapted to the changing value of the final output thickness of said moving web.

Claim 16

A thickness control apparatus as defined in claim 1, wherein the gap calculator means and the thickness control means serve for changing the thickness of the moving web from the first value to the second value by substantially changing the roll gap of the first rolL stand to provide for a substantial change in thickness of the web and for changing the roll gaps of the other roll stands to substantially control the tension of the web.

Claim 17

A thickness control apparatus as defined in claim 13, wherein the gap calculator means and the thickness control means change the roll gap of the first stand in accordance with a set value of the final output thickness of the web and change the roll gaps of the other stands in accordance with a set value of the tension adapted to the final output thickness of the web.

Claim 18

A thickness control apparatus as defined in claim 4, wherein the gap calculator means and the thickness control means serve for changing the thickness of the moving web from the first value to the second value by substantially changing the roll gap of the first roll stand to provide for a substantial change in thickness of the web and for changing the roll gaps of the other roll stands to substantially control the tension of the web.

Claim 19

A thickness control apparatus as defined in claim 12, wherein the gap calculator means calculates a roll gap changing value for each roll stand in accordance with the equations Delta S1 1/a1 . Delta hf/hf Delta S2 1/b22 . Delta tb2/tb2 - (b21/b22) Delta S1 Delta S3 1/b33 . Delta tb3/tb3 - (b31/b33) Delta S1 Delta Si 1/bii . Delta tbi/tbi - (bi1/bii) Delta S1 where Delta hf/hf is the final output changing value, Delta Si is the roll gap change value for the ith stand, ai is the coefficient affecting the final output thickness for the ith stand, Delta tbi/tbi is the tension changing value for the ith stand, bi1 is the coefficient affecting tension in the ith stand due to roll gap change in the first stand, and bii is the coefficient affecting tension in the ith stand due to roll gap change in the ith stand.

Claim 20

A thickness control apparatus as defined in claim 12, wherein the gap calculator means calculates a roll gap changing value for each roll stand in accordance with the equations Delta S1 1/a1 . Delta hf/hf Delta S2 - b21/b22 Delta S1 Delta S3 - b31/b33 Delta S1 Delta Si - bi1/bii Delta S1 where Delta hf/hf is the final output changing value, Delta Si is the roll gap change value for the ith stand, ai is the coefficient affecting the final output thickness for the ith stand, bi1 is the coefficient affecting tension in the ith stand due to roll gap change in the first stand, and bii is the coefficient affecting tension in the ith stand due to roll gap change in the ith stand.

Claim 21

A thickness control apparatus as defined in claim 12, wherein the coefficient correcting means corrects the predetermined thickness coefficient values in accordance with the equations a1A hF - hF 1/hF 1 . 1/ Delta S1 where a1A is the corrected thickness coefficient value, hF is the final output thickness after thickness change, hF 1 is the final output thickness before thickness change, and Delta S1 is the first stand roll gap changing value.

Claim 22

A thickness control apparatus as defined in claim 18, wherein the coefficient correcting means includes means for smoothing the corrected thicknesS coefficient value in accordance with the equation a''1A a''1 + sigma (a1A - a''1) where a''1 A is the coefficient after smoothing, a''1 is the coefficient adapted and corrected in the previous schedule, and sigma is a constant.