Equivalent fatigue load in machine-tool probabilistic reliability. Part II: Calculation methodology and practical applications

This paper deals with the calculation and practical application of equivalent fatigue load in probabilistic reliability. To illustrate the physical meaning and practical use of the theoretical formulae derived in Part 1 of this paper, Part II considers the design example of a multicut semi-automatic lathe. It analyses the power and torque characteristics and special statistical law of load and speed change for the lathe. Equivalent fatigue loads with specified reliability for the important driving elements of the lathe under various working conditions are found on the basis of calculating the reliability factor, the power utilization and the speed change factor. Use of the equivalent fatigue load determined in the paper to design the lathe elements would enable it to obtain the expected reliability.