Flexible Follower Response of a Translating Cam with Four Different Profiles for Rise-Dwell-Fall-Dwell motion
The flexible follower response of a translating cam with four different profiles for rise-dwell-fall-dwell (RDFD) motion is investigated. The cycloidal displacement motion, the modified sinusoidal acceleration motion, the modified trapezoidal acceleration motion, and the 3-4-5 polynomial motion are employed to describe the rise and the fall motions of the follower and the associated four kinds of cam profiles are studied. Since the follower flexibility is considered, the contact point of the roller and the cam is an unknown. Two geometric constraints formulated to restrain the unknown position are substituted into Hamilton’s principle with Lagrange multipliers. Applying the assumed mode method, one can obtain the governing equations of motion as non-linear differential-algebraic equations. The equations are solved using Runge-Kutta method. Then, the responses of the flexible follower undergoing the four different motions are investigated in time domain and in frequency domain. Keywords—translating cam, flexible follower, rise-dwell-falldwell, response
Stability of motion of the cam–follower system
Abstract In this paper, the dynamics of cam mechanism is analyzed. The mechanism is modeled as a cam–follower-driveshaft system where the flexibility of the camshaft and of the follower are considered. The non-linear and damping properties of the system are also taken into consideration. For constant angular velocity of the cam the mechanism is modeled as a two-degree-of-freedom system. The mathematical model of the system is described with two coupled parametrically excited non-linear second-order differential equations. The stability of motion of the system is investigated. Based on the criterion of stability the method for obtaining cam profile is developed. The conditions for stable and asymptotic stable motion of the follower are analytically determined. The obtained analytical results are compared numerical ones. The solutions are in good agreement.
New approach to vision-based BGA package inspection
Ball grid array (BGA) techniques have developed very fast due to the advantages of more I/O ports, small size, and so on. In this paper, a vision-based algorithm for BGA package inspection is proposed to accurately estimate center and diameters of solder-balls of BGA packages, so that defects of BGA packages, such as missing or extra balls, oversize or undersize balls, over-height or under-height balls, and pitch can be detected for ensuring the quality of BGA packages.