Abstract:The knotter bracket supports a series of executive parts of the knotter, and its quality directly affects the knotters knot rate. In order to eliminate the influence of casting deviation of bracket blank on machining quality, based on threedimensional scanning technology, the deviation distribution rule and deviation size of the same batch of casting bracket blank were obtained. A method of adjusting the machining position of bracket axle hole deviated from the ideal position was put forward by deducing the coordinate transformation rule of axle hole center under different space coordinate system. Aiming at the five different space axle holes and one cam surface, the five axis NC machining technology and special fixture of the bracket were designed. The machining method of five shaft holes with different spatial surfaces and one cam surface by onetime installation and clamping was designed. The processed bracket was assembled by this method and other parts into knotter, a series of executive parts cooperated accurately, and the square bale tying test was completed. The test result showed that based on the five axis NC machining method, the proposed deviation compensation method and the designed special fixture, the machining of the five different space axle holes and one cam surface can be realized by onetime installation. The relative position and angle of each axle hole on the knotter bracket were accurate, and the knotting action was accurate and reliable, the finished rate of the bracket processing was 99%, and the square bale knotting rate was 100%.