This paper proposes design of cam-follower velocity curve by using B-spline polynomials. B-spline polynomials are smooth curves defined by control points. Curve shape can be modified by changing the control points. The traditional design method for improving the motion characteristics of the follower is to find an optimum displacement curve for which follower velocity, acceleration curves to be continuous and their peak values as small as possible (i.e. minimum jerk). B-spline polynomials of degree three and six control points are used in design of follower velocity curve. The B-spline curve is used to approximate the various basic curves which have better motion characteristics. A computer-aided design and computer-aided manufacturing (CAD/CAM) system is developed which generates follower motion curves, i.e. displacement, velocity, acceleration, jerk and cam profiles. An analysis is carried out on B-splines with basic curves for maximum accelerations to select the best cam follower motion. It also provides cam profile coordinates to manufacture a cam on computer numerical control (CNC) machines.Keywords: disc-cams; cam profile, B-spline; computer numerical control (CNC); computer-aided design and computer-aided manufacturing (CAD/CAM); R-D-R-D (rise-dwell-return-dwell) IntroductionA cam is mechanical member used to transform rotary motion into translating or oscillating motion to its follower by direct contact (Roth Bart 1956, Jensen 1965. Cam may be a plate cam or a disc cam which is cut out of a piece of flat metal, drum cam in which a groove is cut on the surface of cylinder, globoidal cam and circular cam. Applications of these cams are found in packaging machines, wire-forming machines, internal combustion engines, mechanical and electronic computers. Requirements for high performance of such machinery demands efficient methods for the design and manufacture of cams.In a cam-follower mechanism, the load produced by inertia forces induces deflections and creates vibrations. These affect the operating life of the cam. So the design of motion curves to minimise dynamic loading is of importance for high-speed cam mechanisms. It is well known that the velocity and acceleration curves are required to be continuous and to have the peak values as small as possible (i.e. minimum jerk). The purpose of this paper is to develop a CAD/CAM system for cam-follower mechanisms and to design follower velocity curve using B-splines in view of improving motion characteristics.

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Engineers & technologists contribute significantly in our social development, economic progress, and enhancement of social and physical infrastructure. Industry in general and manufacturing in particular are facing unprecedented challenges due to globalization. Consequently, the business environment of manufacturing enterprises is facing increasing complexity. The engineering graduates and researchers with the ability to understand the technological complexities, the creative arts and skills are increasingly sought after by industrial and business world. Team-based activities are of great importance for students to learn and tackle and solve the complex global issues at later life. Self study and own initiatives of engineering students at learning stage enable and sharpen them to emerge out as highly acceptable engineers. The Washington Accord which emphasizes on outcome based learning is gaining increasing acceptance among many countries.

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Optimization of any aerospace product results in increasing payload capacity of space vehicles. Essentially weight, volume and cost are the main constraints. Design optimization studies for aerospace system are increasingly gaining importance. The problem of optimum design under uncertainty has been formulated as reliability-based design optimization. The reliability based optimization, which includes robustness requirements leads to multi-objective optimization under uncertainty. In this paper Reliability, based design optimization study is carried out under linear constraint optimization to minimize the weight of a nitrogen gas bottle with specified target reliability. Response surface method considering full factorial experiment is used to establish multiple regression equation for induced hoop stress and maximum strain. Necessary data pertaining to design, manufacturing and operating conditions are collected systematically for variability study. Structural reliability is evaluated using Advanced First-Order Second-Moment Method (AFOSM). Finally, optimization formulation established and it has been discussed in this paper.