Failure Analysis of Spline Shaft in Beco Lathe
- PDF / 1,661,047 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 92 Downloads / 270 Views
TECHNICAL ARTICLE—PEER-REVIEWED
Failure Analysis of Spline Shaft in Beco Lathe V. Praveen Kumar • G. Kempulraj Shaju K. Albert
•
Submitted: 6 May 2013 / in revised form: 9 July 2013 / Published online: 23 August 2013 ASM International 2013
Abstract The failure of Heavy Duty Facing Lathe has been systematically investigated using fractographic, metallographic, and analytical stress analysis methods. Failure occurred during machining of a large flange, the tool post had a collision with jaw of the rotating chuck and the spline shaft inside headstock was broken into two pieces. A detailed analysis of the fracture surfaces revealed partial damage of the surfaces due to their rubbing in operation and cleavage fracture in the remaining part of the surfaces. The stress analysis indicates that sudden reversing of the spindle had resulted in the stresses exceeding the fatigue limit of the shaft material. These stresses led to the formation of microcracks at the circlip groove. The collision accelerated the sudden failure of shaft. This failure analysis has led to identification of root cause and its elimination with corrective measures undertaken. Keywords Microcrack Microhardness Effective torque Fatigue Micrograph Angular deceleration
V. Praveen Kumar (&) G. Kempulraj Central Workshop Division, Indira Gandhi Centre for atomic Research, Kalpakkam 603102, India e-mail: [email protected] S. K. Albert Material Technology Division, Indira Gandhi Centre for atomic Research, Kalpakkam 603102, India
123
Introduction The Short Bed Heavy Duty [1] conventional Lathe of Beco make housed at CWD, IGCAR was procured in the year 1991. It is used for machining large diameter components. It has a power house with a motor of capacity 40 hp. Main parts are head stock (head stock gear train, main spindle, feed gear box, and chuck), bed, saddle (cross slide, swivel top slide, and apron) and tailstock as shown in Fig. 1. The main spindle has a range of 18 spindle speeds from 10 to 500 RPM (Table 1).
Nature of Problem A stainless steel flange of diameter 1.3 m and 20 mm thick was under machining in auto feed movement of tool post. The main spindle stopped its rotation and the lathe could not be operated. So the head stock top cover was opened to view the assembly inside. It was observed that the spline shaft which drives the main spindle was broken as shown in Fig. 2. The CAD model of the headstock assembly is shown in Fig. 3. The pulley receives drive from main motor and drives the adjacent spline shafts through gears. The main spindle receives drive from the spline shaft which is located below through gear drive. During preliminary investigation, it was found that the tool post had hit the rotating jaw of the chuck. However, it was difficult to conclude that hitting of the tool post against the rotating jaw of chuck was the only cause of this failure. Under normal circumstances, the chuck should have stopped either by slipping of the belts or the stopping of the motor. Fracture of the spline shaft was unexpected. Hence
Data Loading...
