Revamping Shaft Design for Combating Fatigue Failure
- PDF / 2,398,383 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 44 Downloads / 214 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Revamping Shaft Design for Combating Fatigue Failure Piyas Palit . Urbi Pal . Prabhash Gokarn . Samiran Kanrar
Submitted: 17 June 2020 / in revised form: 24 September 2020 / Accepted: 1 October 2020 ASM International 2020
Abstract This paper gives insights on the failure analysis of the non-drive shaft of a conveyor in a coke plant of an integrated steel plant. The failure of the shaft was investigated in order to determine the root cause and contributing factors. Investigation methods included visual examination, optical and scanning electron microscope analyses, chemical analysis of the material, mechanical tests and life calculations based on design. The overall appearance of the fracture surface of the 45C8 grade shaft indicated rotating bending fatigue failure from a step location. Microstructural analysis revealed a crack from the sharp step and no metallurgical abnormalities. Apart from the metallurgical analysis, the design of shaft was also verified by calculating step profile, fillet radius and calculated stress in actual condition. It revealed that a shaft with a minimum diameter of 70 mm, made of 45C8 steel, can withstand the actual stress acting on it. In this design, the shaft diameter was found to be 65 mm which is insufficient to bear the actual stress. Shaft failures can be reduced by preventive mechanical maintenance and using safe design. To enhance the shaft life without an increase in shaft diameter, we recommend that the material be changed to 42CrMo4 grade steel, which, when appropriately heat
P. Palit U. Pal (&) P. Gokarn Central Laboratories, Scientific Services Division, Tata Steel Limited, Kalinganagar, India e-mail: [email protected] P. Palit U. Pal P. Gokarn S. Kanrar Mechanical Maintenance, Tata Steel Limited, Kalinganagar, India S. Kanrar Mechanical Design, Tata Steel Limited, Kalinganagar, India
treated, has higher stress limit, along with a modification in the step profile with a proper fillet radius. Keywords Fatigue Step profile Allowable stress Shaft diameter
Introduction Coke is the primary source of heat and acts as the reducing agent in blast furnaces. Coal is converted to coke by carbonization in the absence of air; the process is shown in Fig. 1a. During the feeding of hot coke to the Coke Dry Quenching (CDQ) bucket, the dust collecting setup collects dust from different generation points, i.e. the CDQ charging and discharging points and during transportation. The collected coke dust comes to the cyclone separator and passes through a dust conveyor chain (DCC). The separated dust is transported in a bucket elevator to a pugmill for binding and compacting the coke dust, making it easier to transport and store in the raw material handling yard. This is shown in the flow chart, Fig. 1b. Conveyor belts are used to transport the coke dust and any failure in the conveying system results in a loss of production. The non-drive shaft of the coke dust chain conveyor failed after 4 months of service. This shaft is connected t
Data Loading...
