Abstract: Because the existing method to design closed noncircular gears cannot satisfy an arbitrarily given transmission ratio, a new design method based on compensation is proposed to create noncircular pitch curve by transmission function. The mechanism and design steps of the method are given. According to the characteristics of smooth curve and closed pitch curve, the pitch curve equations to satisfy the known transmissions ratio are derived. Then on the basis of the non-sinusoidal oscillation form of continuous casting mould, a pair of noncircular pitch curves is built to adjust this movement. In view of the undercutting and excessive pressure angle as a result of wide range of transmission ratio, the method of series combination of two pairs of noncircular gears is presented, and the method of designing their pitch curves is given. In an actual engineering application, pitch curves are computed respectively to achieve non-sinusoidal oscillation by one and two pairs of noncircular gears, which illustrates the practicability of the proposed method.

Key words: Noncircular gear, Non-sinusoidal oscillation, Pitch curve, Serial gears