An ejection mechanism has a base, a rotation disk and a feeding station. The base is configured for mounting of the rotation disk and the feeding station, The base further includes an arched guiding track, and the arched guiding track is disposed around the rotating gear. The rotation disk is fan-shaped and is rotatably coupled to the base by a rotating shaft such that the rotation disk is aligned above the arched guiding track. the rotation disk is further provided with an arched row of teeth on a bottom of the rotation disk corresponding to the rotating gear of the base. The rotation disk driven by the rotating gear causes the arched row of teeth to rotate and also to simultaneously cause the rotation disk to rotate around the rotating shaft on the arched guiding track. The ejection mechanism which is suitable for different sizes of elbow pipes.