The invention aims to provide a multi-section molded line
cam, which comprises an actuating travel section and a return travel section. The actuating travel section corresponds to two forward uniform acceleration stages, three forward
constant speed stages and two forward uniform deceleration stages of movement rules of a
plunger driven part, and the return travel section corresponds to a backward uniform acceleration stage, a backward
constant speed stage and a backward deceleration stage of the movement rules of the
plunger driven part. A working section comprises the three
constant speed stages, the second uniform acceleration stage and the first uniform deceleration stage of the actuating travel section. The speed of the first constant speed stage of the working section is v1, the speed of the second constant speed stage of the working section is v2, the speed of the third constant speed stage of the working section is v3, and the speed of the backward constant speed stage is v4. The oil
injection pressure and oil injection speed of main injection are increased, different requirements of oil injection of each stage for the oil
injection pressure and the oil injection speed during
multiple injection are combined, and the aims of lowering the working
noise of an engine, reducing the emissions of pollutants and improving an oil injection atomization effect are fulfilled.