Title of Invention

ON LINE GAUGEWISE SHEET CLASSIFICATION SYSTEM FOR SHEET SHEARING LINE

Abstract

A system for classifying cut-sheets of desired dimensions from shearing line of a plant and a method for classifying cut-sheets of desired dimensions from shearing line of a plant in a steel industry. The system involving shearing assembly having means for measuring dimensions of a continuous running strip and means for cutting the same operatively connected to means for storing the desired dimensions of sheets to be obtained, sensor means for sensing the dimensions of the cut sheets, means for comparing the sensed data with said stored data; means to selectively separate the cut sheets as acceptable and not acceptable based on whether the cut sheets are within the acceptable limits of the desired gauge tolerances of the sheets. The system would provide for classifying cut-sheets of desired dimension with more control and precision.

Full Text

FIELD OF THE INVENTION The present invention relates in general to a system for classifying cut-sheets of desired dimensions from shearing line oi" a plans and in particular to a method for classifying cut-sheets of desired dimensions from shearing line of a plant In a steel industry. BACKGROUND OF THE INVENTION In finishing mills of an integrated steel plant, hot rolled coils after being processed through several units such as pickling line, cold reduction mill, bell annealing line and skin pass mill are brought to shearing lines. Here the cold rolled doils are transferred into sheets of desired lengths and gauge within tolerance limits as specified by the customers. In shearing lines known in the art, roll of continuous strip is uncoiled, and after passing through pinch rolls, this strip is side trimmed with disc shears of desired width, Thereafter, the strip passes through an isotope gauge sensor, which measures thickness of the strip. The strip is then fed to strip levelers. Thereafter, Halden shear cuts the strip into specified ordered lengths. The shear frame is mounted in roller body on the driving shaft. It is driven in such a way that at the time of cutting, the shear knives will move at the same speed as the strip. The Halden shear cuts in such a way, that a sheet length of 600 to 1280 mm can be cut, if the shear cuts at each swing. However, there lengths can be doubled, tripled or quadrupled,' if one, two or three mis-cuts (rotation of shear blade without cutting) are introduced for desired cut length. In the shearing lines known in the art, segregation of sheets within specified tolerance ranges and outside such tolerance ranges were done manually with the help of calipers. Prior to such manual classification, a mechanical 2 system was present for the purpose, which has now become obsolete because of its drawbacks. In brief, known techniques could not produce cut-sheets of desired length within gauge tolerance with precision. OBJECTS OF THE INVENTION It is an object of the invention to provide a system for classifying cut-sheets of desired dimension whereby disadvantages of the prior art, as described hereinbefore are obviated. It is a further object of the instant invention to provide a method for classifying cut-sheets of desired dimensions. The system of the instant invention employs PLC (Programmable Logic Controller) based classification system operatively connected to a shearing assembly, which automatically detects the cut-sheets outside gauge tolerance and diverts them to reject piler, and the cut-sheets of within gauge tolerance to prime piler for further processing such as packaging, shipping etc. This combination of shearing assembly with PLC based classification system was hitherto unknown and it yields distinct advantages over the existing systems known in the art. The system of the present invention yields cut-sheets of desired dimensions. It also ensures automatic calculation of number of sheets in a packet as per desired weight, logical marking of sheets as good or bad as per specified gauge tolerance, tracking of cut-sheet by proximity sensors inspite of waviness and wobbling, control of diversion mechanism to segregate prime and off-gauge sheets and initiating advance action to compensate for slow response of pneumatic gate along conveyor 3 belt of shearing line. The system of the instant invention also ensures use of on-line user configurable operational parameters such as sheet length, sheet width, pile width, sheet gauge, positive and negative gauge tolerance and so on. All these aspects were not taught by systems known in the art. SUMMARY OF THE INVENTION : Accordingly, the present invention a system for obtaining cut sheets of desired dimensions comprising a shearing assembly having means for measuring dimensions of a continuous running strip and means for cutting the same operatively connected to means for storing the desired dimensions of sheets to be obtained, sensor means for sensing the dimensions of the cut sheets, means for comparing the sensed data with said stored data; means to selectively separate the cut sheets as acceptable and not acceptable based on whether the cut sheets are within the acceptable limits of the desired gauge tolerances of the sheets. According to a preferred embodiment, the present invention also provides a system as described hereinbefore wherein said means for storing the desired dimensions of sheets comprises a PLC based classification system. According to another preferred embodiment, the present invention also provides a system as described hereinbefore wherein said means for comparing the sensed data with a said stored data, comprises a shaft encoder. According to another preferred embodiment, the present invention also provides a system as described hereinbefore wherein said means to selectively separate the cut sheets comprises a means for counting said cut-sheets. 4 According to further preferred embodiment, the present. invention also provides a system as described hereinbefore wherein said means for counting cut-sheets comprises a 4-digit BCD (Binary Coded Decimal) counter. According to another preferred embodiments, the present invention also provides a system as described hereinbefore wherein said means for sensing the dimensions of the cut sheets comprises tracking sensors provided along conveyor belt of said shearing assembly. In accordance with another aspect, the present invention also provides a method for classifying cut sheets of desired dimensions using the system as described hereinbefore. BRIEF DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWING The objects and working of the invention will be better understood on perusing the following non-limiting description with reference to the accompanying drawing wherein; Fig. 1 illustrates a sectional view of the system in accordance with the invention for obtaining cut-sheets of desired length and gauge within specified tolerance. Fig. 2-9 illustrate the sequence of events to make the system under Fig. 1. The following terminologies used hereinafter have been elucidated as below for better understanding of the inventicn. These parameters are entered in the PLC system operatively connected to the shearing assembly of the system of the invention. 5 Sheet gauge : This parameter corresponds to sheet gauge of the running strip. The gauge value is to be entered in the PLC system on the basis of µm (micron). As an example, if gauge of running sheet is 1.2 mm, then a value 1200 is to be entered. +ve sheet gauge tolerance : This parameter corresponds to upper gauge limit. This parameter is entered the PLC system in terms of µm (micron). As an example, if a value of 100 is entered for this parameters and sheet gauge is 1.2 mm i.e. 1200 µm, then upper gauge limit will be. calculated internally in the PLC system as 1300 µm (i.e. 1200 µm + 100 µm = 1300 µm). -ve sheet gauge tolerance : This parameter corresponds to lower gauge limit. This parameter is entered in the PLC system r in terms of µm (micron). As an example, if a value of 100 is entered for this parameter and sheet gauge is 1.2 mm i.e. 1200 µm, then lower gauge limit will be calculated internally in the PLC system as 1100 µm (i.e. 1200 µm - 100 µm = 1100 µm). Sheet length : This parameter corresponds to cut-length of sheet. This parameter is entered in terms of mm. As an example, if a length of cut sheet is 2500 mm, then a value of 2500 is to be entered in the PLC system. Sheet count by number/count based on pile weight : This parameter corresponds to set value of sheet counter, which counts prime sheets. The selection of sheet count mode by number or count based on calculation of pile weight is selectable by a toggle switch inside operator desk. If this switch is in up position, desired number of sheets in a piler will be decided by entering a number on operator console, and if this switch is in down position, the desired no. of sheets will be calculated automatical y based on sheethength, sheet width; and specific gravity of sheet steel and pile weight . as entered by operator. As an example for the mode sheet count by number, 6 it this parameter is set to 100, then sheet counter counts prime sheets from 0 to 100. The sheet counter rests to 0 when count reaches 100, and thereafter count starts again from 0. Gauge sumple-to-Sample distance. On running strip gauge is mesured continuously, and infinite no. of gauge values are available on a sheet. To detect a sheet as a good (within gauge tolerance limits) or bad (out of tolerance limits) a limited no. of gauge values are sufficient. Therefore, gauge values at fixed distances are considered for calculation. As an example, if cut sheet length is 2500 mm, we may consider 250 mm as gauge sample-to-sample distance parameter and therefore, we will get 10 (i.e. 2500/ 250 = 10) gauge values on a sheet of length 2500 mm for calculation. No. of bad gauge sample tolerance : This parameter corresponds to no. of bad samples upto which a sheet will not be marked as bad. If we consider above example in gauge sample-to-sample distance, we will get 10 gauge sample values. If we set no. of out of gauge tolerance sample tolerable parameter as 5, it means that the system will not detect a sheet as bad upto 5 out of tolerance gauge samples. As soon as no. of out of tolerance gauge samples reaches 6, the system will detect a sheet as bad. The system of the invention consists of a Programmable Logic Controller (8) net worked with an operator console (12) operatively connected to shearing assembly. The shearing assembly comprises rotatably mounted uncolier (13) and shear (16), as well as Isotope gauge (14). A pneumatic gate (6) is provided along conveyor belts (17) for guiding sheets to prime piler (5) and reject piler (5). 1 is analog value of gauge sensor. The function of gauge sensor is to provide thickness data of continuous sheet. 2 is pulse train of rotarv encoder. The function of rotary encoder is to provide a train of pulses while a leveler roll is rotat. The rotation of leveler roll is directly proportional to the length of continuous sheet passing through it. 3 is shear 7 pulse. This pulse is generated whenever shear cuts a sheet. The shaft encoder is coupled with one of leveler rolls. Strip-leveler is just before shear mechanism. Shaft encoder is coupled with one of the levelers. Continuous strip is run through the uncoiler and then to an isotope gauge for measurement of thickness of running strip. The strip is then fed to strip levelers lor leveling to strip before it is cut by shear. The isotope gauge is installed before the shear assembly- The distance between the gauge and the shear is fixed and operator enters the sheet length at operator console located at a distance from the PLC through a 2-wire communication bus. Therefore, how many numbers of sheets and/or what fraction of a sheet is trapped between the two becomes known. These sheets are marked in memory of PLC as logical sheets. The logical marking of sheets is done with the help of a shaft encoder. Alternatively, sheets can be marked logically on the basis of cut-to-cut time of sheets. The sheets, which are logically, formed bears status as good sheet or bad sheet depending upon specified gauge tolerance value. Operator sets the number of gauge data samples and tolerance number of bad samples for a sheet. The status of a sheet is marked as good on the basis of checking no. of gauge data samples outside the tolerance ranges but not exceeding the tolerance number of bad data samples. A rotary encoder (15) is coupled with one of leveler rolls of strip leveler and it provides a train of pulses, as a continuous sheet moves through the leveler. The pulses of the encoder is fed to the PLC through pulse interface module and the voltage level of these pulses are of 24 VDC. Inductive proximity sensors (4) are located along the conveyor belts (17) of the shearing line, including one mounted just before the pneumatic gate (6). A limit switch is mounted on shear assembly, which gives a pulse as soon as a sheet is cut. The output signal of isotope gauge in the range of to 10 VDC, corresponding to gauge of continuous strip, is taken to the PLC with proper S isolation and signal conditioning. A 4-digit BCD (Binary Coded Decimal) counter is used for counting number of prime sheets in a sheet packet. In case of failure of operator console, there is provision of entering all above data through a 4-digit thumb-wheel switch, a multi-position selector switch and a bank of toggle switches and these data are viewed on 4-digit BCD counter for verification. Whenever the proximity sensors (4) encounter a sheet, the stack memory status for that particular proximity sensor is updated with the status of that particular sheet (i.e. good or bad). A proximity sensor mounted just before pneumatic gate senses leading edge of incoming sheet. Once the sheet is detected by this proximity sensor the system checks the memory for the status of that particular sheet. If the sheet is found to be bad/off-gauge, control command will be given by the system for operating the gate for diverting that off-gauge sheet to reject piler. Else, the cut sheet is diverted to prime piler for collection of cut sheet of desired length and gauge tolerance. The timing pulse for opening or closing diversion mechanism is variable and it is a function of conveyor speed and auto-adjustable percentage of good sheet or percentage of bad sheet which passes through the diversion mechanism. The present invention has been described with reference to the preceding description and accompanying drawing but in no way is limited to such description and drawing and it is to be understood that various modifications of the invention is possible within the purview of what has been described hereinbefore and claimed in the appended claims. 9 We Claim; 1. A system for obtaining cut sheets of desired dimensions comprising a shearing assembly having means for measuring dimensions of a continuous running strip and means for cutting the same operatively connected to means for storing the desired dimensions of sheets to be obtained, sensor means for sensing the dimensions of the cut sheets, means for comparing the sensed data with said stored data; means to selectively separate the cut sheets as acceptable and not acceptable based on whether the cut sheets are within the acceptable limits of the desired dimensions of the sheets. 2. A system as claimed in claim 1 wherein said means for storing the desired dimensions of sheets comprises a PLC based system. 3. A system as claimed in any preceding claim wherein, said means for comparing the sensed data with said stored data, comprises a shaft encoder. 4. A system as claimed in any preceding claim wherein said means to selectively separate the cut sheets comprises a means for counting said cut-sheets. 5. A system as claimed in claim 4 wherein said means for counting cut- sheets comprises a 4-digit BCD counter. 6. A system as claimed in any preceding claim, wherein said means for measuring dimensions comprises as isotope gauge. 7. A system as claimed in any preceding claim vherein said means for cutting continuous running strip comprises a shear. 10 8. A system as claimed in any preceding claim wherein said shearing assembly comprises a leveling means for leveling said running strip. 9. A system as claimed in claim 8 wherein said leveling comprises a leveler with lever rolls. 10. A system as claimed in claim 9 wherein a rotary encoder is coupled to one of said rolls, said encoder being adapted to generate pulses and feed said pulses to said PLC based system. 11. A system as claimed in any preceding claim, wherein said means for sensing the dimensions of the cut sheets comprises tracking sensors provided along conveyor belt of said shearing assembly. 12. A system as claimed in any preceding claim wherein said PLC based system comprises an input and display means. 13. A system as claimed in claim 12, wherein said input and display means comprises an operator console. 14. A system as claimed in claim 12 wherein said input means comprises a 4-digit thumb-sheet switch, a multi-position selector switch and a bank of toggle switches. 15. A system as claimed in any preceding claim wherein a limit switch is mounted on said shearing assembly, said limit switch being adapted to give a pulse to said PLC based system to which it is operatively connected, as soon as a sheet is cut. IS 16. A system as claimed in any preceding claim, wherein said isotope gauge is adapted to give a analog value to said PLC based system reflecting thickness of running strip measured. 17. A system as claimed in any preceding claim, wherein a pneumatic gate is provided along conveyor belt of said shearing assembly, said gate being operatively connected to said means to selectively separate cut sheets as acceptable and not acceptable. 18. A system for obtaining cut-sheets of desired dimensions, substantially as herein described, particularly with reference to the accompanying drawing. 19. A method for obtaining/classifying cut sheets of desired dimensions, using the system as claimed in any preceding claim. A system for classifying cut-sheets of desired dimensions from shearing line of a plant and a method for classifying cut-sheets of desired dimensions from shearing line of a plant in a steel industry. The system involving shearing assembly having means for measuring dimensions of a continuous running strip and means for cutting the same operatively connected to means for storing the desired dimensions of sheets to be obtained, sensor means for sensing the dimensions of the cut sheets, means for comparing the sensed data with said stored data; means to selectively separate the cut sheets as acceptable and not acceptable based on whether the cut sheets are within the acceptable limits of the desired gauge tolerances of the sheets. The system would provide for classifying cut-sheets of desired dimension with more control and precision.

Documents:

00109-cal-2001-abstract.pdf

00109-cal-2001-claims.pdf

00109-cal-2001-correspondence.pdf

00109-cal-2001-description(complete).pdf

00109-cal-2001-drawings.pdf

00109-cal-2001-form-1.pdf

00109-cal-2001-form-18.pdf

00109-cal-2001-form-2.pdf

00109-cal-2001-form-3.pdf

00109-cal-2001-letters patent.pdf

00109-cal-2001-p.a.pdf