INDIVIDUAL DRIVE, CHAIN DRIVE AND U- SEAL MECHANISM IN ROLLER HEARTH NORMALISING FURNACE Akash Kumar Mechanical Engineering Dronacharya College of Engg. Gurgaon, Haryana Abstract:- This project deals with the study and review of STUDY THE CHAIN DRIVE, INDIVIDUAL DRIVE MECHANISM ROLLER AND FUNCTION OF U-SEAL IN FURNACE OF PLATE MILL. Normalizing is a process of heating the plates to soaking temperature depending upon the composition of metal, cooling them in air. An industrial furnace in which stacked items are heated in an insulated car that is rolled out of the furnace on rollers or chutes, guided by rails or a grooved way. A crane is used to load and unload items for processing on the car, or roller hearth. Sand or water are used to seal gaps between the roller hearth and the walls in order to decrease the intake of air into the furnace. The heating time of plates in the furnace depends on the thickness of the plate. Equipment to heat metals to the desired temp for Change shape, Change properties. Liquid/gaseous fuel or electricity type of fuel are mostly used. Provision of water U-seal in the gas pipe line of normalizing furnace for gas safety. Keywords: U-seal, roller hearth normalizing furnace INTRODUCTION Roller Hearth Normalising Furnace Roller Hearth Normalising Furnace an industrial furnace in which stacked items are heated in an insulated car that is rolled out of the furnace on rollers or chutes, guided by rails or a grooved way. A crane is used to load and unload items for processing on the car, or roller hearth. Sand or water are used to seal gaps between the roller hearth and the walls in order to decrease the intake of air. Charging of Plates 1. Plates placed on the stacks, are picked up by depiler one by one and placed on the charging side roller table of the furnace. 2. Care should be taken to charge plates of one thickness range at a time, as the speed of the roller hearth is set as per thickness of the group of plates. 3. There should not be any abrupt change in the specific heating time of the specific heating time of the groups, the timing to be reset after the overlapping group of plates are discharged from the furnace. 4. There should not be any abrupt change in the specific heating time of the groups, the timing to be reset after the overlapping group of plates are discharged from the furnaces. 5. For the plates of thickness more than 40 mm oscillation regime of the roller hearth is to be followed. 6. As the roller hearth speed is being controlled speed is being controlled from CP-38, the operator of this pulpit should be informed about the thickness of the plates in advance, so that he can set the speed. 7. When plates are placed on the charging side roller table. A charging report is made in a proforma in four copies. This report includes, normalising serial no, plate no., cast no., grade, sale order no., actual size of the plate and finished plate size. 8. After charging about 10 to 12 plates, the copies will be sent to leveller (CP-40) stamper painter, shear and piler staff. 9. Care should be taken to send these copies before plate reaches there. 10. Prior to charging into the furnace the gap between the manipulator is set manually as per the width of the plates. 11. While charging, plates should be placed on the roller table, straight, centrally and slowly. 12. Bend plates, should not be charged. 13. The person at the depiler has to check the availability of plates on the stacks. If any one of the stack is empty, it is to be filled immediately. IJIRT 142875 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 46
14. While charging the plates, a minimum required gap is to be maintained between two plates. 15. Charging should be stopped immediately if there is any hold up in the equipment after furnace or if there is any equipment after furnace or if there any problem in the furnace. Oscillation is manual mode and bring down the temperature gradually depending on the duration of the delay. 16. Any defect in the depiler equipment should be immediately brought to the notice of shift 17. During charging of plates, control operator should follow and ensure correct movement of plates inside the furnace on the roller hearth. It is prohibited to allow shifting of plates towards the wall. 18. In case of shifting of plates are observed inform shift incharge immediately. HEATING OF PLATES 9. Necessary action must be taken to overcome any fault. Concerned heating staff should make necessary entries in the log dook. DISCHARGING OF PLATES 1. Plate discharging from the furnace is a continuous process. 2. When plate is coming out of furnace the lowering and lifting tracks of plate convey or should be in lower positions. 3. Once plate reaches the roller table before plate conveyor, it should be immediately transferred to conveyor bed to make the tracks ready to receive the successive plates. 4. While conveying plates on the conveyor, a minimum required gap is to be maintained between two plates. 5. Any defect in the equipment should be brought to the notice of shift 6. Any hold ups in the equipment after the furnace, the in the equipment after the furnace, the CP- 38 operator should be informed immediately. LEVELLING OF PLATES FIG: PLATES INSIDE THE FURNACE 1. The furnace is operated as per technological instructions (refer heating instructions). 2. Depending on the grades of steel proper temperature has to be maintained in the furnace. 3. The fuel used should be burnt completely within the furnace. Burning of fuel in the flue duct is strictly prohibited. 4. Furnace pressure should kept positive at the level of hearth (roller) for this it is necessary to keep a pressure of + 5 mm WC. 5. The temperature of the flue gases just before the dampers should be properly controlled. The temperature of the flue gases should not exceed 700 C. 6. Air/fuel ratio should be correctly monitored so that fuel gets completely burnt within the furnace. Soot formation is prohibited. 7. Formation of scale during heating should be kept to minimum. 8. Any fault in the instruments should be immediately brought to the notice of shift 1. Levelling is done for plates of thickness from 5mm to mm only. 2. Plate or thickness more than 20mm are let through the leveller by increasing the gap between the leveller rollers. 3. Before feeding the plates into the leveller, plates are to be centered with the help of manipulators. 4. Required gap is to be maintained between rollers as per the thickness of the plate. 5. Thickness change for the plates should be strictly observed, so that gap can be set properly. 6. Leveller cooling system should be checked now and then, physically from the site, as there is no annunciation system for cooling water failure. IJIRT 142875 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 47
7. Any defect in the leveller or manipulator should be brought to the notice of shift 8. Any hold up in the equipment should be informed immediately to CP-38. 9. Back up rolls must rotate along with the work rolls during idle running. If they fail to rotate they are adjusted with the help of proper packing. 10. Scale is cleaned periodically from work rolls and back up rolls by compressed air. 11. Dial reading should correspond to the actual gap. 12. There should not be overlapping of plates during levelling. 13. Plates in skew condition should not be levelled. 14. No foreign material should be present on the plate during levelling. 15. The levelling machine should be stopped immediately if jamming of metal occurs between work rolls, it is prohibited to operate the screw down mechanism or reverse the levelling direction in such a case. 16. Jamming of metal is a serious breakdown which damages the mechanism and all precautions should be taken to avoid it. Chain drive Mechanism In Chain drive mechanism each roller is drived by the chain with the help of motor and reducer. Chain drive is a way transmitting mechanical power from one place to another. The power is conveyed by a roller chain, known as the drive chain or transmission chain, passing over a sprocket gear, with the teeth of the gear meshing with the holes in the links of the chain. The gear is turned, and this pulls the chain putting mechanical force into the system. The invention provides a chain transmission mechanism for a Roller-Hearth furnace, which comprises a transmission chain wheel, a tension pulley and chains which consist of a plurality of pitch chains, wherein the chains are arranged on the transmission chain wheel and the tension pulley. The outside of each chain is provided with planer mound layer in section. The planer mould mound layers are fixed with the furnace wall through a height adjusting mechanism. The chains are driven by the transmission chain wheel to move. Chain drive Mechanism advantage 1. Through one chain the complete line shaft revolve due to this it provides or rotates all the roller of the furnace. 2. By using chain drive mechanism in furnace-1 we get high velocity ratio. 3. The power consumption in chain drive is low as compared to individual drive mechanism. Chain drive mechanism disadvantage 1. The initial set up cost of chain drive mechanism is high. 2. The chances of breakage of chain drive is rarely happens. 3. This mechanism uses lubrication for smooth drive of shaft but in individual drive mechanism lubrication is not required. 4. Small sprocket is used in upper portion of the chain drive so to maintain proper tension in the chain. 5. Sometimes due to heavy load the line shaft chain got break down due to that the power will not be transferred to the roller. 6. After prolonged usage of chain it gets loose to maintain tension the chain either we have to remove some teeth of chain of make the chain tight. 7. The chain linked to the reducer 800 sometimes got break down due to load tolerance. 8. If the chain got breaks down in middle of the process the roller in the roll table also got damaged the rollers either may bend from the neck or some crack will appear on its neck or at its barrel. 9. The time consumption in joining the chain to one breaks or damaged frequently due to this process is not used more. Individual drive mechanism In individual drive mechanism each roller in the furnace is drive by an individual motor. Speed of the each roller is controlled by the help reducer coupled with the motor. Since each roller in the furnace is controlled by the separate motor, there is less chance of breakdown. Advantage of individual drive mechanism 1. The initial set up cost of individual drive system is low as compared to chain drive system. IJIRT 142875 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 48
2. The breakage of disc in individual drive system is not frequently or year can say it occurs sometimes. 3. If one disc got damaged the entire process does not get affected because other discs will revolve & roll table continue to move. 4. The time taken by the disc to get correct is about 2 to 3 hours. 5. If 2 or 3 discs got damaged in the shaft then also the roller will continue to move as plates will pass upon it without any cracks. 6. The speed of the roller can be increased or decreased as per the need in individual drive mechanism. 7. In this to each roller individual motor is installed so if one roller got affected other may continue to work. 8. Maintenance cost in changing the discs of the shaft is also low. 9. Due to individual drive mechanism the chances of bending of roller containing disc in very less. Disadvantages of individual drive mechanism 1. More power consumption occur in individual drive mechanism. 2. Since each roller have individual motor so the cost of the motor & its instalment is also high. 3. If more than 2 or 3 discs of the shaft got damaged the new shaft must be installed to avoid any cracks or bars in the hot plate. U-SEAL U-SEAL before U-seal is a process used to avoid leakage of gases (Mixed gas) from the pipeline and to prevent the hazard caused by leakage of gases by filling the U-shaped gas pipe with clean water at a certain level. The water comes from the water pipeline and deliver it to the inlet of the U-SEAL and filling it upto given level and through outlet valve of U-SEAL excess water gets discharged. This discharging of water gives 100% satisfaction that leakage of gas will not occur during the maintaince of furnace and whole system. In U-SEAL drain valve is also located at the bottom of it which is used to empty the U-SEAL when we need to start the system or say process to work. Through drain valve the water gets discharged and inlet valve is closed so that no supply of water takes place. After that mixed gas is supplied in the gas pipeline. When gases comes out of burner in the furnace, burner is switched on to fire the flame by bringing the flame near the burner of furnace and hence the overall process work. Advantage of using U-SEAL 1. The U-shaped pipeline prevents leakage of gas through the gas pipeline due to its U-shaped design and filling of water in the u-seal. 2. U-seal gives 100% surety. 3. The overall design of the U-SEAL is so appropriate & creative that it gives proper satisfaction against of gas. CONCLUSION Roller Hearth Continuous Normalising Furnace is a heat treatment method, to enhance the mechanical properties of the plate. In roller hearth continuous normalising furnace plate inside the furnace is move from input to output door of the furnace with the help of roller which is drive either by the chain drive mechanism or by the individual drive mechanism. Chain drive mechanism and individual drive mechanism is operated with the help of motor coupled with the reducer. Individual drive mechanism required less maintaince than the chain drive mechanism and also consume less power as compared to chain drive mechanism. The overall shutdown of furnace due to breakage of chain in chain drive mechanism is overcome by the new design i.e. individual drive mechanism. It also saves the maintaince cost of drive mechanism due to less breakdown of drive mechanism. U-seal is a process used to avoid leakage of gases (Mixed gas) from the gas pipeline and to prevent the hazard caused by leakage of gases by filling the U- shaped gas pipe with clean water at a certain level. IJIRT 142875 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 49
This gives the 100% surety that there is no chance of leakage of gases through the gas pipeline. REFERENCES [1] Bhilai Steel Plant Intranet. [2] Gateway-An Introductory Guide to Bhilai Steel Plant, Edition 2009, Editor - Manas Shukla, DGM (HRD), Bhilai steel Plant. [3] http://www.sail.co.in/pnu.php?tag=bhilai (Retrieved on 1/7/2012) [4] Daniel Automation Specification Sheet for roughing and finishing stand. [5] Enterprise Resource Planning Software, Plant Maintenance Module. [6] Davies, Clive (1970). Calculations in furnace technology (1st ed.). Pergamon Press. ISBN 0-08-013366-5. [7] Goldstick, R. and Thumann, A (1986). Principles of waste heat recovery. Fairmont Press. ISBN 0-88173-015-7. [8] ASHRAE (1992). ASHRAE Handbook. Heating, ventilating and air-conditioning systems and equipment. ASHRAE. ISBN 0-910110-80-8. ISSN 1078-6066. [9] Perry, R.H. and Green, D.W. (Editors) (1997). Perry's Chemical Engineers' Handbook (7th ed.). McGraw-Hill. ISBN 0-07- 049841-5. [10] Lieberman, P. and Lieberman, Elizabeth T (2003). Working Guide to Process Equipment (2nd ed.). McGraw-Hill. ISBN 0-07- 139087-1. [11] Furnaces, Incinerators, Kilns at DMOZ IJIRT 142875 INTERNATIONAL JOURNAL OF INNOVATIVE RESEARCH IN TECHNOLOGY 50