World Journal of Science and Technology 2012, 2(4):20-23 ISSN: 2231 2587 Available Online: www.worldjournalofscience.com

Proceedings of " A National Conference on Advances in Mechanical Engineering (NCAME-2012) Held at R.C.Patel Institute of Technology, Shirpur, Dist. Dhule,Maharastra,India.

April 21, 2012

Design of tilting ladle transfer car for steel Industries Prajakta Bawiskar1, Sachin Kamble1 and Kiran Bhole1

1Datta Meghe College of Engineering, Airoli, Navi Mumbai, India

Abstract- This paper gives idea about designing of tilting ladle transfer car for steel Industries. Tilting Ladle transfer cars are used to carry hot metal ladle from the HMDS section (Hot metal dispensing section) to the convertor section. The ladle carrying the hot metal consists of impurities in the form of slag which is precipitated over the hot metal. This precipitated slag is removed in tilting operation by slag raking machine. After titling operation the transfer car carries the material to the convertor section. The paper includes designing of structural and hydraulic circuit for carrying and tilting ladle of ladle transfer car. The design process involves hand calculation and the prepared design is then presented in the 3D drawings using modeling software. Keywords: Tilting ladle, Transfer car, Design steps

INTRODUCTION Tilting Ladle transfer cars are used to carry hot metal ladles from the HMDS Plant to the convertor section. The molten metal consists of slag and impurities which affect the purity of the final metal. The titling operation of the tilting car is used to tilt the ladle carrying the hot metal and the slag raking machine removes the slag from the tilted ladle. This innovative system is used to carry the hot metal as well as remove the slag over the molten metal.

Fig1. Proposed tilting ladle car

The figure. 1 shows the pictorial sketch of the proposed idea

of tilting ladle transfer car.The operation of the car is in a hot region . The ladle carrying the molten metal consists of liquid metal which is at 1350 C. The ladle carrying the liquid metal is lined by a refractory which protects the ladle metal contact with the molten metal. The ladle is provided with a trunion on the either side by which the ladle can be lifted or kept on the car by a lifting tackle . The lifting tackle is engaged in the main hook of the main hoist of the crane . The crane required for handling this huge capacity ladle is a four girder 350 T EOT crane.The ladle is provided with a lip section which has a spout with lip at 12 degrees. This spout is required for the generation of smooth pouring of the liquid metal during the pouring in convertor.Ladle car is to be designed using the safety parameters and most of the operations are automatic or should have a remote control to avoid the human intervention in the working of car. TECHNICAL AND FUNCTIONAL DESCRIPTION The tilting car is to be designed for the following technical specifications. Weight of the molten metal with the ladle and refractory lining to be carried: 280 Tonnes Speed of the car : 0 to 30 m/ min Tilting angle of the ladle : 0 to 40 Tilting Speed : Three minutes for 40 tilting (forward movement ) Rail for the movement of the car : CR120 Rail Span : 3800 mm Tilting initiation : By joystick Distance of the remote control operation : 300 mm Design standard : IS 807 for structural design. With these inputs the task is to design a tilting car The transfer car shall be self-propelled type and shall have two (2) individual wheel drives The power shall be transmitted from a squirrel cage motor through a flexible coupling to gear unit. The gear unit shall be coupled to the driven track wheel and connected with car frame by a torque arm or should be bolted to the frame. The two

*Corresponding Author

Srihari Prasad A Department of Mechanical Engineering, K.L.University, Vaddeswaram, Guntur, A.P., 522502., India Email: srihari.anne@gmail.com

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electric motors shall be provided with brakes and shall be easily detachable from gearbox during maintenance. The hot metal ladle should be placed by EOT crane whose hook will be given by the customer. After placement of the ladle the crane hooks should be released easily without any interference with car frame. There should be sufficient maintenance. Suitable refractory lining provision to be made on the platform and sides to prevent damage due to accidental spillage of metal at pouring and HMD station. The tilting of the ladle shall be done with the hydraulic system. The hydraulic power pack shall be operated from locally and from control room. The tilting cylinders shall be operated with the help of joysticks. The tilting cylinders mounting arrangement shall be strong enough to handle the 280 ton ladle. Enough protection for cylinders to be provided and cylinder seals to withstand the temperature surrounding the heat zone. Hydraulic hoses should withstand the temperature in case any spillage of hot metal around the car. The ladle tilting should operate between Zero (ladle vertical) to 40 deg only. Two proximity/limit switches have to be used to sense two positions of ladle. One proximity switch senses ladle fully tilted position at 40 deg. while the other senses ladle in vertical position. Suitable provisions to be made to mount safety switches. When Car is travelling on rail, i.e. the tilting cylinder should not operate even if joystick operation is done. Once hydraulic power pack is started , car should not travel even if supply to gear motor is given. Hydraulic Cylinder operated by joystick. Joystick operation energies solenoid of direction control valve causing cylinder to move. Once ladle has reached 40 deg. tilted position, proximity switch activates. This signal is used to cut off solenoid of direction control valve from joystick. Similarly when ladle has returned back from tilted position, 0 deg. proximity switch at 0 deg. position activates. This signal is also used to cut off joystick from solenoid of direction control valve. This will not allow operation of Hydraulic cylinder even if joystick is operated for return motion of cylinder The protection/heat shields shall be provided for the car drive units, hydraulic system and cables to prevent damage due to leakage/spillage of metal from sides of the ladles at pouring station and slag raking machines. Rest technical specification and dimensions as per the attached reference tilting transfer car and hot metal ladle drawings. General Arrangement drawing shall be submitted for approval with showing the ladle over car, hook clearance, protection heat shield, drive, hydraulic power pack, cylinders, make of components, technical specification, etc.,. DRIVE ELEMENT DESIGN. Design of the wheels of the tilting transfer Car. Speed of the Car 30 m/ min =30000mm/min Load on the tilting car : 280T (carrying wt)+ 60T self weight= 340 T Deciding the no of wheels As the surface of the rail is wavy or has troughs and crests the design of wheel is to be done by considering pin joints. Hence the number of wheel for pin joint will be two at every location. Hence the no. Of wheel = 8 nos. Load on each wheel = 42.5 Tonnes Speed = (pi)*d*n=3.14*d*n As the load is 42.5 tonnes and as per crane design standard and considering CR120 Rail Diameter= 1.5 W/ a = (1.5*42500/90)= 708 .33mm. Considering a further factor of safety the standard wheel selected is

800 mm. RPM of wheel = Speed/(3.14*d) =30000/(3.14*807)= 11.83 m/m Considering the rpm of the wheel we select the drive elements Gear box and the motor Motor used in steel plants is a three phase supply. The motor to be used is a six pole. Speed of the motor = (120 * f)/P = 120*50/ 6 = 1000 rpm Hence the rated rpm = 960 rpm . Gear box ratio = 960/11.83 = 81.12(82) Motor KW rating Power at the wheel P= 2*pi*N*T/(60*1000) P =2*3.14*11.83*T/(60*1000) Torque on the wheel = 170000*(Wheel dia /2) =170000*(403.5)= 68595000kg-mm =685950000N-mm P =2*3.14*11.83*685950000/60*1000=849.347 For 150% over load = 849.347*1.5=1274.1 KW Gear box ration =80 Motor KW required = 16 KW Considering the intermittent loading and the impact factor the motor KW is 30KW STRUCTURAL ELEMENT DESIGN. As the ladle is hot when it carries the hot metal the material used in the transfer car should be also able to with stand the heat dissipated without any distortion. Hence the material which is selected for Construction in IS 2002 which is a material having a very less thermal coefficient of expansion.

Fig 2.Transfer car in about to tilt position

The loading pattern is considered by taking the beam as a simply supported beam . The highest loading will be as shown in Fig.2 The ladle rests at three points on the tilting frame surface .

Srihari Prasad A et al.,

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Fig 4. Box Design

Hence each surface has been considerd with a load of 108 Tonnes. Reaction at the point A + Reaction at the point E =50+108+5= 163T In a simply supported beam the moments at the supported point are zero.

MA= -108*500-50*649-5*250+1450RE

RE=61 T RA=101T Max bending moment = 108* 500= 54000000 kg-mm Section modulus is now to be worked out.

Fig 3. Transfer car in Tilt position.

The section to withstand the heavy bending moment will be a box which would be developed by using plates and welded connections.

Fig 5. Section Modulus Of Box.

The section modulus of the above box section considered =17326950 mm3 Hence the stresses will be = 54000000/17326950 =3.11 kg/mm2 HYDRAULIC SYSTEM DESIGN The hydraulic system will be designed as shown in the Fig. 8. CG design during tilting ,The CG were calculated in each stage of tilting as in fig. 7. CAD software of Autocad is used. Now the design will be optimized using the solidworks The design of trolley in Solid works is as shown in Fig.6

Fig 7. CG calculation at different angle

. Fig 8. Hydraulic system Design

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There are two cylinders which do the tilting operation .These cylinders work on hydraulic pressure . The following are the engineering considerations in the design of this cylinders. Load on the cylinders 320 tonnes Operating pressure considered is 120 bar Pressure =Force /Area Area of cylinder = 320/120 As there are two cylinders Area= 320*1000/(120*0.01*2)=133333mm2 Diameter of the cylinder = 210 mm During design we will take higher bore on availability. Hence the bore diameter is taken as 280 mm The hydraulic power pack has the following features Hydraulic oil : VG 68 No of cylinders 2 The tilting operation valve : proportional valve PVG32( directional as wellas a proportional control valve) Flow of the pump 63 litre sper minute . Forward speed = 485 mm/s Rod end diameter 140 mm .

CONCLUSION The design of the structures their optimisation is done using hand calculations and Finite element analysis by using softwares like Solidworks.The drive calculations are done by using the drive standards and are effective for the VVVF drive also. The hydraulic design is done using the Rexroth and Sauer danfoss instruction codes. This is the basis of implementation in steel plant design. REFERENCES

[1]. Solidworks User manual guide :Dassault Systems

[2]. Hydraulics Design Manual : Gl Rexroth

[3]. Structural design: IS 807

[4]. Transfer Planning of Molten Metals in Steel Works by Decentralized Agent Junji KIKUCHI , Masami KONISHI and Jun IMAI.

[5]. Tilt Testing Of two Heavy Vehicles and related performance issue. By Dr Hans Prem ,Director and Senior Consultant.

[6]. E.J. Reilly and A.C. Nelson.1920.Metal transfer car PatentAug 3.