Title of Invention

A METHOD AND SYSTEM FOR ONLINE ESTIMATION OF COIL WEIGHT INCOILER ROLL IN A ROLLING MILL.

Abstract

The present invention relates to a method for on-line estimation of coil weight in a coiler roll in a rolling mill comprising allowing the starting end of a coil of sheet material from an uncoiler roll to pass through a nip provided between a pair of work rolls and winding the so passed coil end on a coiler roll, the coil end from the uncoiler roll being deflected in a first deflecting zone to the nip position as necessary and being further deflected in a second deflecting zone to the coiler roll from the nip as necessary, each of the said two deflection zones being provided with respective shaft encoding to provide necessary information such as coil length passing there between to a measurement and central zone, the measurement and central zone also having information from the uncoiler zone and coiler zone through tacho information about amount of coil un-coiled respectively, there being a control panel associated to the measurement and central zone; the measurement and control details being further processed in a development and process monitoring zone to provide information like instantaneous thickness, main stand roll force, instantaneous coil weight in coiler and uncoiler, total length rolled in a campaign to facilitate roll change, the information thus made available in said process monitoring zone being displayed in a display zone with a report printing zone providing process report, the coil weight in the coiler roll being determined based on instantaneous coiler diameter using a ratio technique, where, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and toiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coils. There is also provided a system therefore.

Full Text

Introduction to the Field of Invention: This invention relates to an improved method and system for on-line coil weight estimation in a rolling mill In another aspect, this invention relates to a method and auto slow down mechanism for skin pass mill. Prior Art and Drawbacks: It is already known to estimate the weight of coil in a rolling mill according to the requirements of customers. It is well known that a skin pass mill is a crucial place in any cold rolling mill mainly because of the fact that its output in many cases is sent directly to the customer. With increasing availability of options to th« customers, the technical specifications of their orders have been narrowing in tolerance day by day. One such exempt* is the individual coll weight very precisely specified by the customer. This is a problem for low weight coils, as it needs to be partitioned from a bigger coil. Pure visual estimation gives a rough idea of weight because slight variation in thickness or width can amount for too much variation in coil to coil weight. Objects of the invention: It is an object of the invention to propose an improved method to determine the specific weight of coil with very little tolerance. It is another object of this invention to determine the weight of a coil based on calcutation of instantaneous coiler diameter using ratio technique. It is another object of the invention to propose such a method for the determination of the weight of a coil based on the fact that for any fixed duration of time the length of strip passing over dummy roll is same as length of strip being wrapped on the coiler It is a further object of the invention to propose such a method in which using two shaft encoders attached to coiler and dummy roil respectively, we can count the number of rotations made by cotter roil and dummy roll. It is a further object of the invention to propose a system for the determination of the weight of a coil based on calculation of instantaneous coiler diameter using ratio technique. It is a further object of the invention to propose a system, which is based on the fact for any fixed duration of time, the length of strip passing over dummy roll is same as length of strip being wrapped on the coiler. It is a still further object of the invention to propose a system in which using two shaft encoders attached to coiler and dummy roll respectively, we can count the number of rotations made by coiler roll and dummy roll. It is an additional object of the invention to propose such a system, which can not only estimate the online coil weight accurately but also stop the mill automatically after expecting a preset weight in the coiler. grief Statement of the invention-. According to this invention there is provided a method for on-line estimation of coil weight in a colter roll in a rolling mill comprising; a. allowing the starting end of a coil of sheet material from an uncoiler roll to pass through a nip provided between a pair gf work rolls and winding the so passed coil end on a coiler roll, b. the coil end from the uncoiler roll being deflected in a first deflecting zone to the nip position as necessary and being further deflected in a second deflecting zone to the coiler roll from the nip as necessary, c. each of the said two deflection zones being provided with respective shaft encoding to provide necessary information such as coil length passing there between to a measurement and control zone, the measurement and control zone also having information from the uncoller zone and coiler zone through tacho information about amount of coil un-coiled respectively, there being a control panel associated to the measurement and central zone; d. the measurement and control details being further processed in a development and process monitoring zone to provide information like instantaneous thickness, main stand roll force, instantaneous coil weight in coiler and uncoiler, total length rolled in a campaign to facilitate roll change, the information thus made available in said process monitoring zone being displayed in a display zone with a report printing zone providing process report, the coil weight in the coiler roll being determined based on instantaneous coiler diameter using a ratio technique, where, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and coiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coils. In this method, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and coiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coil. The nip between the work rolls is adjustable according to the thickness of the coil by means of pressure adjustable back up rolls, one on either free end of the work roll vertically below the nip. The shaft encoding is carried out as follows to provide the number of rotations in coiler/uncoiler and deflector roll, which is a measure of coiler diameter. a. Two shaft encoders of 2500 pulses per revolution rating are connected to the deflector roll through suitable couplings; b. The signal from the shaft encoders is connected to VHSC module i.e. counter module in the PLC, which counts these pulses tacho readings as it calculates the diameter from ratio technique To achieve this, the measurement and control zone is associated with mill control contacts and provide information like mill speed reference, stand speed feedback reference, coil diameter in the uncoiler zone, coil diameter in the coiler zone as well as coil thickness as standard data for calculating the weight of the coil in the coiler zone at any given point of time using the mathematical equation herein described. According to another aspect, there is provided a system for on-line estimation of coil in a coiler roll in a rolling mill comprising a frame/stand having mounted on its one side thereon a uncoiler roller adopted to receive a coil of sheet material from which predetermined weight of sheet material is to be coiled on a coiler roller situated on the other side of the stand, a pair of work rods in pressure contact with each other in between said uncoiler roll and coiler roll having a nip there between, each said work roll being provided with a back up roll adapted to exert pressure on the work rolls, there being also provided a first deflector roll in between said uncoiler roll and the said nip and a second deflector roll between said nip and said coiler roll to ensure taught condition when a sheet material travels from the uncoiler to the coiler roll, the system further having a tachometer each associated with the uncoiler roll and the coiier roll, there being provided a shaft encoder each in operationally associated with each said deflector roll, there being also provided a measurement and control unit in operational association with the said tachometers and with shaft encoders on the one hand and with a control panel and a software development and process monitoring unit on the other hand, the system further having a visual display unit and a process report printer unit for displaying and printing the values developed. In this system, the measurement and control unit includes a display unit for strip or sheet width, a display unit for input coil weight, a display unit for output coil weight and a display unit for strip/sheet thickness associated with first shaft encoder on the uncoiler roll zone which further includes display means for customer details and customer requirement, speed indicators and operating switch. For facilitating the work, the measurement and control unit also includes display unit for output coil weight, a display unit for coil length and respective units for strip width, strip thickness, output coil weight all associated with the second shaft encoder on the coiler roll zone and further includes units for indicating campaign length. The system is provided various contacts for mill control and the system includes a volume Isolator through which are connected units for (i) mill speed reference (ii) stand speed feedback signal, (iii) strap thickness and for any other value as may be required. In a preferred embodiment, the uncoiler and coiler roll are positioned spaced apart, the two deflector rolls, the two shaft encoders, the two work rolls and the two backup rolls all accommodated in the spaced apart distance between the uncoiler and coiier roll and the two work rolls are positioned vertically over one another and each is pressured by a backup rod. It is preferable to have trie top work roll provided with a backup roll vertically at top white the bottom work roll is provided with a backup roll vertically from below whose pressure contacts are adjustable and the two work rolls and each of the two deflector rolls are in the same horizontal plane but in a horizontal plane higher than the horizontal plane of the uncoiler and coiler rolls. Brief Statement of the Invention with Reference to the Accompanying Drawings: In the accompanying drawings: Figure 1 briefly represents a block schematic of the system of the invention. Figure 2 shows further detail of the Figure 1 with other operational auxiliaries and units. Figure 3 illustrates schematically the coil weight measurement scheme. Detailed Description of the Drawings: The invention will now be more fully described with reference to the accompanying drawings. \X will be seen from Figure 1 that the system (i) comprises a coil of sheet material (2) mounted on an uncoiler roller.(2) The system is further provided with a deflector roll (3), a bridle top roll (4) in the same horizontal plane and spaced apart from each other and a coiler roll (5) all suitably mounted. In between the deflector roll (3) and the bridle top roll (4), there is provided a pair of work rolls (6a, 6b) with the nip in between. The work rolls (6a, 6b) are in pressure contact with respective backup rolls (7a and 7b). All these rolls are suitably mounted freely rotatable on the main stand not shown. In a preferred embodiment, the uncoiler roll and the coiler roll are equal in the diameter Similarly, the deflector roll, the bridle top roll and the pair of work rolls are also of the same diameter for preferential operational reasons. In the same way, the two backup rolls are of the same diameter. It is also preferred to have the deflector roll, the bridle top roll, the work roils and backup rolls from the same material of sufficient length for uniform operation. In addition to the above constructional features, the system includes measurement and control unit (8), a control panel (9), display unit (10), process monitoring unit (11) and process report unit (12). There is further provided a tacho mechanism (13) in operational association with uncoiier roil (2) and another tacho mechanism (14) in operational association with coiler roll (5). This two tacho mechanisms are further in operational association with the measurement and control unit (8). In order to help further recordal of details, the measurement and control unit (8) is also operationally associated with the deflector roll (3) through a shaft encoder (15) and also with the bridle top roll (4) through another shaft encoder (16). The units 8, 9, 10, 11 and 12 are operationally associated as shown in the drawings. Referring to Figure 2, it will be seen that the block diagram shows the following units. 1. Shaft encoder (deflector roll) 2. Shaft encoder (dummy roll) 3. Display for strip width 4. Display for input coil weight 5. Display for output coil weight 6. Display for strip thickness 7. TWS for set campaign length 8. TWS for customer ID. 9. Slowdown i. Indicator 10. Slowdown ii. Indicator 11. ASD selection switch 12. TWS for strip width 13. TWS for strip thickness 14. TWS for set output coil weight 15. TWS for output coil no. 16. Display for output coil weight 17. Display for campaign length 18. Campaign length high ind. 19. Campaign length reset sw. Move 20. Various contacts for milt control 21. PC and printer 22. Various analog signals through vol. isolator Figure 3 shows the portion of the system for coll weight measurement. Details of Determining the Weight of Coil: For the purpose, PLC with VHSC module, PC, shaft encoders, thumb wheel switches, selection switches and display meters were used. All other hardware were already existing in the mill. Analogue signals like stand speed feedback signal and thickness measurement signal were brought into the PLC. Some digital mill contacts like forward run, forward thread, coiler tension on etc. were also used. a. Software implementation: The measurement of coil weight in coiler required calculation of on-line diameter measurement in the first place. This diameter was converted to volume by using strip width information finally based upon this volume weight was calculated. For auto slow down length information was needed and this was calculated with the help of thickness information of the strip. The various measurement methods have been described in the following part in order they were needed and developed. b. Outer diameter measurement: An incremental shaft encoder is fitted on a dummy roll in the coiler side, the contact of strip with dummy roll should be such that minimum or null slippage occurs. For a very small time period (025 sec max.), the number of rotations made by dummy roll (Ndummy) and coiler mandrel (Ncoiler) are measured through very high speed counter module in the PLC. If the fixed diameter of dummy roll is Odummy, assuming no slippage, outer coiler diameter Dcoiler can be given by Dcoiler = {Ndummy/Ncoiler} * Ddummy................(1) c. Auto slowdown mechanism for skin pass mill: i. In order to facilitate partitioning of higher weight input coils into coils of lower weights, the operator has been provided with a feature for stand speed feedback signal is also brought to the PLC. This is required in order to calculate the expected length of coil (slow down length) which will be wrapped in the coiler if mill is stopped now with normal deceleration. The expected weight of slow down length is also calculated length matches with 'set output weight", slow down is initiated automatically. ii. For provision of auto slow down of mill at tail end of the coil, no extra input other than mentioned above was required. The slow down is initiated based upon the calculation of remaining coil length in uncoiler and coil length expected to stop the mill to standstill from present mill speed. Normally coil in uncoiler is not as tightly packed as coiler and also the contact of strip with uncoiler side deflector roll is not very good. This may lead to miscalculation of diameter, which in turn may affect the calculation of remaining coif length in uncoiler. d. Weight calculation formulate based on diameter of coil. Since the diameter of each winding consistently varies, how do you estimate diameter of the coil? The coil weight estimation is based on calculation of instantaneous coiler diameter using ratio technique. For any fixed duration of time, the length of strip passing over dummy rod is same as length of strip being wrapped on the coiler. Using two shaft encoders attached to coiler and dummy roll respectively, we can count the number of rotations made by coiler roll and dummy roll. Ratio of diameter is equated with inverse ratio of number of rotations made by the two rolls. Since only coiler diameter is only variable in the equation, it can be calculated. Coiler weight measurement: Weight of coil in coiler is estimated indirectly using online coiier diameter as main parameter. Other parameters used for such estimation are strip width (SW) and specific gravity of steel (5 steel). The volume of the coil can be given as Vcoil = Pi/4* (Dcoiler2 - Did2)* SW where Did is the internal diameter of coil and equals to the fixed diameter of coiler mandrel. Therefore, the weight of the coil can be given as Wcoil = Pi/4 (Dcoiler2 - Did2)* SW* d steel....................(2) e. Coiler length measurement: As we shall see in the auto stow down scheme that coil length measurement is very crucial to the accuracy of final coil weight. One important factor required for length calculation is strip thickness, which was obtained from existing gamma ray thickness measurement system and the average thickness (t) was used for the calculation of coil length. Assuming that strip is tightly would and there is no gap between successive turns of the strip, the coil can be assumed as a very long strip of steel with length (I), thickness (t), width (SW) and specific gravity (d steel). The weight of such strip can be given by Wcoil=1* SW*t*d steel......................(3) From equation (2) and (3) length of the coil can be calculated as L = Pi/(4*1) * (Dcoiler2 - Did2)..................(4). Calibration details: The estimated weight in the coiler deviates by less than 3% of actual weight measured through weight bridge system. The data is attached for reference. Fault diagnoses details: Dynamic mimic displays on the terminal depicting many useful data to enable easy fault diagnostics of the mill. Figure for the same is attached. In actual trial runs made at different times at different dates, it has been found that in some cases, the actual weight and calculated weight of the coil were almost same with an error of -0.12% very negligible recordal of less weight. Similarly, it has also been observed that a higher weight recordai of up to about 5.6% than the calculated weight has been found. These variations are attributed to several operational adjustments and it is possible to obtain very negligible error in weight determination. WE CLAIM: 1. A method for on-line estimation of coil weight in a coiler roll in a rolling mill comprising. a. allowing the starting end of a coil of sheet material from an uncoiler roll to pass through a nip provided between a pair of work rolls and winding me so passed coil end on a coiler roll; b. the coil end from the uncoiler roll being deflected in a first deflecting zone to the nip position as necessary and being further deflected in a second deflecting zone to the coiler roll from the nip as necessary; c. each of the said two deflection zones being provided with respective shaft encoding to provide necessary information such as coil length passing there between to a measurement and central zone, the measurement and central zone also having information rrom me uncoiler zone and coiler zone through tacho information about amount of coil un-coiled respectively, there being a control panel associated to the measurement and central zone; d. the measurement and control details being further processed in a development and process monitoring zone to provide information like instantaneous thickness, main stand roll force, instantaneous coil weight in coiler and uncoiler, total length rolled in a campaign to facilitate roll change, the information thus made available in said process monitoring zone being displayed in a display zone with a report printing zone providing process report, the coil weight in the coiler roll being determined based on instantaneous coiler diameter using a ratio technique, where, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and coiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coils. 2. A method as claimed in claim 1, wherein, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and coiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coil. 3. A method as claimed in claims 1 and 2, wherein, the said nip between the work rolls is adjustable according to the thickness of the coil by means of pressure adjustable back up rolls, one on either free end of the work roll vertically below the nip. 4. A method as claimed in claims 1 to 3, wherein, the shaft encoding is carried out as follows to provide the number of rotations in coiler/uncoiler and deflector roll which is a measure of coiler diameter a. Two shaft encoders of 2500 pulses per revolution rating are connected to the deflector roll through suitable couplings. b. The signal from the shaft encoders is connected to VHSC module i.e. counter module in the PLC, which counts these pulses tacho readings as it calculates the diameter from ratio technique. 5. A method as claimed in claim 4, wherein, the measurement and control zone is associated with mill control contacts and provides information like mill speed reference, stand speed feedback reference, coil diameter in the uncoiler zone, coil diameter in the coiler zone as well as coil thickness as standard data for calculating the weight of the coil in the coiler zone at any given point of time using the mathematical equation herein described. 6. A method for on-line estimation of coil weight in a coiler roll in a rolling mill substantially as herein described 7. A system for on-line estimation of coil in a coiler row in a rolling mill comprising a frame/stand having mounted on its one side thereon a uncoiler roller adopted to receive a coil of sheet material from which predetermined weight of sheet material is to be coiled on a cotter roller situated on the other side of the stand, a pair of work rolls in pressure contact with each other in between said uncoiler roll and coiler roll having a nip there between, each said work roll being provided with a back up roll adapted to exert pressure on the work rolls, there being also provided a first deflector roll in between said uncoiler roll and the said nip and a second deflector roll between said nip and said coiler roll to ensure taught condition when a sheet material travels from the uncoiler to the coiler roll, the system further having a tachometer each associated with the uncoiler roll and the coiler roll, there being provided a shaft encoder each in operationally associated with each said deflector rod, there being also provided a measurement and control unit in operational association with the said tachometers and with shaft encoders on the one hand and with a control panel and a software development and process monitoring unit on the other hand, the system further having a visual display unit and a process report printer unit for displaying and printing the values developed. 8. The system as claimed in claim 7, wherein, the measurement and control unit includes a display unit for strip or sheet width, a display unit for input coil weight, a display unit for output coil weight and a display unit for strip/sheet thickness associated with first shaft encoder on the uncoller roH zone. 9. The system as claimed in claim 8, which further includes display means for customer details and customer requirement, speed indicators and operating switch. 10. The system as claimed in claims 7 to 9, wherein, the measurement and control unit also includes display unit for output coil weight, a display unit for coil length and respective units for strip width, strip thickness, output coif weight all associated with the second shaft encoder on the coiler roll zone. 11. The system as claimed in claim 10, wherein, it further includes units for indicating campaign length. 12. The system as claimed in claims 7 to 11, wherein, there are provided various contacts for mill control. 13. The system as claimed in claims 7 to 12, wherein, the system includes a volume isolator through which are connected units for (i) ml speed reference (ii) stand speed feedback signal, (iii) strap thickness and for any other value as may be required. 14. The system as claimed in claims 7 to 13, wherein, preferably the uncover and cotter roll are positioned spaced apart, the two deflector rolls, the two shaft encoders, the two work rods and the two backup rolls all accommodated in the spaced apart distance between the uncoiler and coiler roll. 15. The system as claimed in claim 14, wherein, the two work rolls are positioned vertically over one another and each is pressured by a backup roll 16. The system as claimed in claim 15, wherein, the top work roll is provided with a backup roll vertically at top while the bottom work roll is provided with a backup roll vertically from below whose pressure contacts are adjustable. 17. The system as claimed hi claim 16, wherein, the two work rolls and each of the two deflectors are in the same horizontal plane but in a horizontal plane higher than the horizontal plane of the uncoiler and coiler rolls 18. The system for on-line estimation of coil in a coiler roll in rolling mill substantially as herein described with reference to the accompanying drawings. The present invention relates to a method for on-line estimation of coil weight in a coiler roll in a rolling mill comprising allowing the starting end of a coil of sheet material from an uncoiler roll to pass through a nip provided between a pair of work rolls and winding the so passed coil end on a coiler roll, the coil end from the uncoiler roll being deflected in a first deflecting zone to the nip position as necessary and being further deflected in a second deflecting zone to the coiler roll from the nip as necessary, each of the said two deflection zones being provided with respective shaft encoding to provide necessary information such as coil length passing there between to a measurement and central zone, the measurement and central zone also having information from the uncoiler zone and coiler zone through tacho information about amount of coil un-coiled respectively, there being a control panel associated to the measurement and central zone; the measurement and control details being further processed in a development and process monitoring zone to provide information like instantaneous thickness, main stand roll force, instantaneous coil weight in coiler and uncoiler, total length rolled in a campaign to facilitate roll change, the information thus made available in said process monitoring zone being displayed in a display zone with a report printing zone providing process report, the coil weight in the coiler roll being determined based on instantaneous coiler diameter using a ratio technique, where, the instantaneous coiler diameter is determined as a ratio between the number of rotations made by the uncoiler roll and toiler roll, said number of respective rotations being made known the above said respective tacho mechanism associated with the respective deflection zones for the uncoiler and coiler zones, the length and instantaneous diameter of the coil being used to determine the volume of the coil with the help of coil width followed by converting the coil volume into weight with the help of the specific gravity of the material of the coils. There is also provided a system therefore.

Documents:

155-cal-2002-granted-abstract.pdf

155-cal-2002-granted-claims.pdf

155-cal-2002-granted-correspondence.pdf

155-cal-2002-granted-description (complete).pdf

155-cal-2002-granted-drawings.pdf

155-cal-2002-granted-examination report.pdf

155-cal-2002-granted-form 1.pdf

155-cal-2002-granted-form 13.pdf

155-cal-2002-granted-form 18.pdf

155-cal-2002-granted-form 2.pdf

155-cal-2002-granted-form 26.pdf

155-cal-2002-granted-form 3.pdf

155-cal-2002-granted-gpa.pdf

155-cal-2002-granted-reply to examination report.pdf

155-cal-2002-granted-specification.pdf