Study On New Profile Of Roller Chain Sprocket Based On ADAMS

The sprocket as the indispensable important mechanical transmission parts in national economy is widely used in mining machinery, agricultural machinery, construction machinery, forestry machinery, petrochemicals, auto assembly line and other transmission machinery. In our country, we have been adopting the three arcs and a straight line tooth profile from Former USSR and Europe, and its transmission performance is better, but the design and manufacture are relatively complex. At the same time, as the chordal action and the meshing impact effect existing in roller chain drive that it is not suitable for high-speed transmission. So it is necessary to develop a new kind of roller chain drive to improve the transmission performance of roller chain mechanism.First of all, the formation mechanism of chordal action and meshing impact of chain transmission is analyzed theoretically, and the compensation measures are proposed. Research on developing new teeth profile sprocket is carried out aiming to decrease the meshing impact and fluctuation of chain under high speed condition. The epicycloid equation of new sprocket is obtained by the premise that the roller rolls without slipping on tooth root; and the new tooth profile equation is deduced by utilizing the method of seeking equidistant curve using envelop, what's more, the design method of epicycloid equidistant line sprocket is obtained according to contriving of international sprocket.Secondly, the traditional roller chain drive models which match the GB1244-85 standard sprockets, the Japanese standard JIS B 1801-90 sprocket and the epicycloid equidistance sprocket are built by means of 3-D modeling technique. The rigid dynamic models of the GB1244-85 standard sprockets, the Japanese standard JIS B 1801-90 sprocket and the epicycloid equidistance sprocket are built by adding constraints such as rotating pair and drive force. The dynamic simulation of drive wheel as the speed of driving sprocket varies from 1,000r/min to 8,000r/min is achieved. The method of new sprocket teeth profile modification is proposed theoretically.Finally, based on the result of the dynamic simulation experiment, the fluctuation of chain, meshing impact between sprocket and roller and the nonuniformity coefficient of driven sprocket angular velocity are comparatively analyzed as using GB1244-85 sprocket, JIS B 1801-90 sprocket and new teeth profile sprocket under the condition of various rotating speed. The simulation results show that the fluctuation of chain is significantly reduced by using asymmetrically modified new teeth profile sprockets, especially when drive wheel speed is higher than 3,000r/min, this advantage is more obvious. By calculating the average of the meshing impact force between sprocket and roller, it is found the value of the new teeth profile sprocket is minimum, and the nonuniformity coefficient of driven sprocket angular velocity is the least too. The result shows that the chordal action and the meshing impact effect can be reduced by using the new teeth profile sprocket. Thereby the vibration and noise of the transmission system can be reduced and the high-speed driving performance is improved.