The Research And Design Of CAD For Cam Based On VB

Cam mechanism has some functions such as transmission, steering and control, and it is extensively used in the machinery industry. According to all kinds of follower systems, it is more common in mechanisms that cam profiles which can achieve the intended movements are designed. The traditional design of cam mechanism is mainly mapping, but this way has low precision and its design period is very long. With the development and widespread of the computers, mapping design is gradually replaced by analytical methods. For the planar cam mechanism with spire and roller followers, this article discovers the unified approaches and methods of cam profiles,curvature radius of cam profiles,mechanical pressure angles and movement laws of cam follower, then on this basis, develops the CAD system of cam. The main work of this article is as follows:1) Firstly, direct-acting follower and swing follower are uniformly expressed as virtual swing Follower, then this article is based on the theory of envelopes for 1 parameter family of curves to establish the unified expression of cam profiles for the planar cam mechanism with direct-acting or swing follower, finally, the planar cam mechanism with roller direct-acting follower is gave an example, the unified expression is verified to be right.2) According to the unified expression of cam profiles and by way of kinematic research and mathematical analysis, the unified expression of mechanical pressure angles and curvature radius of cam profiles are worked out for the planar cam mechanism with direct-acting or swing follower, and then the planar cam mechanism with spire direct-acting follower is gave an example, the unified expression of mechanical pressure angles is verified to be right.3) By way of dimensionless to movement laws and according to the harmonic-trapezoidal combined curve, the unified expression of the general fixed trapezoidal curve is worked out.4) According to the above unified expressions, the CAD system of cam is developed with Visual Basic6.0, and the system's interface and exchanging information between system and users are very convenience, finally, an example of cam design is taken, and the system is verified to be right and feasible.