Abstract: Aiming at the problems of low expansion efficiency and complex structure of the expansion mechanism of the belt conveyor, the existing expansion efficiency and structure of the expansion mechanism of the encircling type, the roller type of the Pallet type and the wire winding type were studied. The existing deficiency of the expansion mechanism of the belt conveyor was summed up, a kind of belt conveyor double expansion mechanism, which was composed of gear-rack mechanism and pulley mechanism was presented. The modeling software and simulation software to build the virtual model of the expansion mechanism was used, the motion pair and carry on the motion analysis was added. Finally, the dynamic characteristics of the telescopic mechanism were analyzed to verify whether the design could meet the requirements of the movement and strength of the cargo. The results indicate that the expansion and contraction process of belt conveyor's double expansion mechanism is smooth and the strength can meet the design requirements. Comparing with the existing belt conveyor's expansion mechanism, the double expansion and contraction effect is obvious, the efficiency of expansion and contraction and the compactness of structure are improved obviously, which provides a powerful reference for the design of belt conveyor for conveying goods in narrow space.

Key words: belt conveyor; double expansion mechanism; dynamic characteristic analysis; virtual model