The Research And Optimal Design Of The High-speed And High-precision Movement Mechanism For SMT Equipments

High-speed and high-precision Placement Machine is the most critical equipment in the SMT equipments, whose speed and accuracy are the most important performance indicators and the motion mechanism with high speed, high precision and high stability is the key to reflect its performance. With the goal of designing a high-speed and high-precision motion mechanism for SMT equipment, some common movement mechanisms in existing Chip Mounter were researched. A new X-Y type movement mechanism with gantry structure was designed after comprehensive analysis of the advantages and disadvantages of the various mechanisms and the initial model of this new type movement mechanism was established. The beam and base of the mechanism were designed in detail, in which the materials, manufacturing methods and structure of parts and structural lightweight were involved.In order to ensure the mechanical strength and stiffness, the mechanical behaviors of the base and beam under the static and dynamic load were researched in ANSYS separately by the static checking and transient kinetic analysis. The dynamic characteristics of the sub-structure of the movement mechanism and overall were studied by modal analysis technology, the analysis of the structure of the natural frequencies and mode shapes showed that the dynamic characteristics of the sub-structure has a very important influence on the overall dynamic performance. What’s more, the weakness or redundancy of the structure has been optimized and the overall dynamic performance was enhanced.A multi-rigid-body model and a rigid-flexible coupling multi-body model of the motion mechanism were established by ADAMS based on combination of rigid and flexible multi-body dynamics theory and finite element method, dynamic simulations were respectively conducted in their full motion cycle to analyze and study the elastic vibration and dynamic accuracy of the actuator (i.e. Placement Head).The accuracy of the modeling of rigid-flexible coupling was verified by the comparison of two kinds of simulation results. According to the results, the structure of the beam has been optimized, which has the greatest impact on the vibration of mechanism, and the vibration significantly weakened as well as the dynamic accuracy has been improved that meets the requirements of the use of high speed and high precision SMT machine.